splicing and repair manual - blair · pdf file2 this material has been designed to cover all...
TRANSCRIPT
Splicing andRepair Manual
Conveyor, elevator and transmission belts
Disclaimer . . . . . . . . . . . . . . . . .Introduction . . . . . . . . . . . . . . . .
Preparing for the splice . . . . . . . . .Take-up position and weight . . . . . . .Belt roll length and diameter . . . . . . .
Materials, Tools and Equipment . . . . .Curling Splice in a Vulcanizer . . . . . .Making a Vulcanized Step Splice . . . . .
Cutting to length, required splicelength, direction of splice
Medium Tension Belting . . . . . . . . .(without a breaker) Step by step procedure
Medium tension/with a breaker . . . .Butyl and EPDM belts . . . . . . . . .
High Tension Belting . . . . . . . . . . .Reduced Ply Belts . . . . . . . . . . . . Steel Cable Belting
Butt splice . . . . . . . . . . . . . . . .Overlap splice . . . . . . . . . . . . . .Splicing damaged or bare cables . . . .Splicing with unequal cables . . . . . . .
Light Weight Belting . . . . . . . . . . .Repairing Conveyor Belting . . . . . . . Splicing Materials . . . . . . . . . . . . .Glossary . . . . . . . . . . . . . . . . .
Tables1 Recommended take-up provisions . . . . . . . .2 Value K for automatic take-ups . . . . . . . . . 3 Recommended splice material usage . . . . .4 Estimating material requirements . . . . . . . . .5 Materials factor . . . . . . . . . . . . . . . . . .6 One-ply knife recommendation . . . . . . . . . .7 Curing time for conveyor belting . . . . . . . . .8 Curing time for plylock belt joint . . . . . . . . .9 Vulcanized splice-required belt length . . . . . .10 Work table for steel cable splicing . . . . . . . .11 Laying out center line - steel cable . . . . . . .12 Cable cutting pattern . . . . . . . . . . . . . .13 Splice materials arrangement - steel cable . . . .14 Cure times and temp for steel cable belt . . . .15 Cable arrangement - overlap splice
#800, 1000, 1150, 1400, 1700 and 1800 . . . 16 Cable arrangement - overlap splice
#2100, 2400, and 2800 . . . . . . . . . . . . 17 Material and curing time -
light weight belts . . . . . . . . . . . . . . . 22 Factors determining whether belt
should be cut and spliced or repaired . . . . .
TABLE OF CONTENTS
Please visit us on the web at www.blairrubber.com
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P. O. Box 4282 � 1252 Mina Avenue � Akron, Ohio 44321 � Phone: (330) 666-3600 � Fax: (330) 666-9334
The Blair Rubber Company provides information, written and verbal, relative to belting which it hasgathered from a multitude of sources. However, such information is offered as a guide only; andtherefore, Blair Rubber Company does not assume liability whatsoever, in regard to the use of thisinformation.
The user of this information must determine the suitability of this information, and if more informationis needed, the user should contact the appropriate belting manufacturer.
Since the application of technical information supplied by Blair Rubber Company may be affected dra-matically by many factors such as, the length of exposure to a particular substance, the concentrationof any such substance, synergistic effects, exposure to more than one substance, and/or a widerange of belting products and temperatures, the enclosed should only be used as a guide. BlairRubber Company, accordingly, disclaims liability for damages of any kind, including consequentialdamages, resulting from reliance on the information supplied herein.
DISCLAIMER
IMPORTANT INFORMATION
1
2
This material has been designed to cover all aspects of splicingconveyor belting. We have taken a step by step approach usingthe methods and procedures proven over the years to providesplices with long trouble-free service. However, it should beemphasized that all splices, whether they be mechanical or vul-canized, are dependent upon three key factors that must be pre-sent in all splice work and these are:
1. Craftsmanship and procedures2. Proper materials3. Proper equipment and tools
Of these, craftsmanship is the most critical to success. The stepdown process is only as good as the splicer’s technique. Caremust be taken while cutting along fabric planes that the plybelow is not nicked which can seriously reduce the overallsplice efficiency.
Avoid taking “short cuts” by reducing carcass step lengths orfill-in fabric used beneath each cover. These procedures are amust to provide satisfactory splice life.
Always make sure the materials and the grade of belting you aresplicing are compatible with each other. Use proper quantitiesas this is vital to a proper flow of materials and bonding duringthe vulcanizing process.
Check expiration dates and throw away materials that are out-dated or contaminated.
Finally, pay careful attention to equipment and tools.Vulcanizers should be checked on a routine basis to assure goodworking order to provide correct temperature and pressure.
Always use tools designed for the task. As an example, ascrewdriver should not be used to separate fabric plies, it cangouge both plies and destroy them. Use a prodder instead.
Never prepare belt ends for splicing in advance. Belting shouldbe prepared only when the splicing process will be completed atthat time.
We are confident that by following the procedures found in thismanual, you will be able to achieve professional results and longtrouble-free service from your belting.
WARNING: Several procedures outlined in this manualinvolve varying degrees of physical risk. Make sure equip-ment to be used is adequate for the job and is in good work-ing condition. Wear protective gloves/equipment whenworking with cutting tools, solvents, etc. When using sol-vents, be sure to follow safety precautions provided by themanufacturer.
INTRODUCTION
Preparingfor theSpliceThe Splicing site - Splicing can bedone more easily on a horizontal runrather than on an incline. Considerthis when you choose the spot atwhich to pull the belt ends together.If splicing is restricted to an incline,it should be done at the lower endwhere the belt can be handled easily.
You’ll need a flat table to work on atthe splicing site. The table should beaccessible from both sides. If it isn’t,build a temporary catwalk alongsideit.
At some installations, a permanentsplicing shanty offers protection forsplicing and repairs regardless of theweather. However, most customersprovide protection under temporarysplicing shelters.
If the conveyor is entirely off theground and several rolls of belting arerequired, consider making all splicesexcept the last one on the ground inline with the let-off facilities. Thefirst roll can be threaded onto the sys-tem and the trailing end spliced to thesecond. This can be repeated untilthe belt is completely mounted.
The last splice will have to be madeat some point on the conveyor deck-ing.
If the best place for splicing is atsome point on the decking and severalrolls of belting are required, the beltcan be threaded by joining the sec-tions with temporary metal fasteners.Then, when each mechanical splicereaches the splicing station, the metalfasteners can be replaced by a vulcan-ized splice.
Preparation for splicing - Beforeattempting either a mechanical or avulcanized splice, consider thesebasic requirements:1. Check the belt ends. Make certainthat both ends are “fresh”. Never
splice with belt ends that have beendamaged or contaminated in service.Cut back until you reach fresh materi-al.
2. Draw proper centerlines.Centerlines are basic to straight-run-ning splices. (They should be funda-mental to all splicing .) Refer totable 9 for details on drawing truecenterlines.
When making a mechanical splice,you can take advantage of the pre-cutparallel edges on all factory-slit belt-ing. Square each belt end by scribinga perpendicular line from one beltedge. (A common mechanic’s squarecan be used here.) Before cuttingalong this line, scribe a second linefrom the other edge. If the two linesoverlap, the belt end is certain tohave a square cut and parallel edges.If the lines intersect, the edges arenot parallel and a centerline must bedrawn.3. Position the take-up pulley - Whensplicing, try to position the take-uppulley to accommodate the totalmovement expected. This belt move-ment would depend on several factorssuch as elongation over the life of thebelt, take-up pulley travel during thestart/stop phase and storage of sparebelting.
If you’re planning on a vulcanizedsplice but take-up movement is insuf-ficient, consider vulcanizing allsplices but one. Leave one mechani-cal splice in the belt until the initialstretch is removed. This may takeseveral weeks of normal operation.Afterwards, the mechanical splice canbe replaced by a vulcanized splice.
Position oftake-up forbelt installationWhen the final vulcanized splice ismade during installation of a convey-or belt, it is very important that thegravity take-up be placed at the prop-er position. There are many factorsaffecting proper position of the take-
up, and it is difficult to assemble def-inite data from which a decision canbe made. In an attempt to set upsuch data, it is assumed that:1 - The proper take-up weight willbe in place for tensioning at time ofmeasurement for the last splice.2 - Belt slack is removed whenlength determination is made for thelast splice.
Position at which take-up should beafter the last vulcanized splice is com-pleted is dependent on many factors:1 - Length of take-up movementprovided.2 - Type of belting being used.3 - Type of starting control on drivemotor.4 - Whether there is a run-in periodwith metal fastened splice before lastvulcanized splice is made.5 - Conditions existing during timeof splicing. When splicing is neces-sary for several lengths of belt on along unit, the belting may be in arelaxed condition for several days ora week. If there is no protective cov-ering over unit, snow or rain may lieon belt. Such a belt will have anincreased amount of initial stretchafter it is put into operation.
Data have been set up to include con-sideration of the first four items.Table 1 lists conveyor center lengthsand possible take-up movements,along with type of belting. Bold-facesentences in paragraphs followingtable give suggestions for positioningof take-up when final splice is made.
3
APPLICATION OF TABLE 1 -Movement A - “Across-line” start.No run-in period. When thisamount of take-up movement is pro-vided and “across-the-line” or stan-dard type of reduced-voltage startingis used with a squirrel-cage motor,belt can be spliced so that approxi-mately 3/4 of take-up movement isleft for stretch. Belt can be splicedin place with no run-in period.
Movement B - Controlled start.No run-in period. With wound-rotormotor and proper controls, or a prop-er combination of motor and fluidcoupling or eddy-current clutch, take-up movements shown under B inTable 1 should be satisfactory. By ...proper controls or ... combination ...is meant a starting in which thebreakaway and accelerating torque isheld to 130% or 140% of operatingtorque. The belt can be spliced sothat approximately 3/4 of the take-up movement is left for stretch. Norun-in period is necessary before finalvulcanized splice is made.
“Across-line” start. No run-inperiod. Movement B also can applywhen “across-the-line” or reduced-voltage starting is used with a squir-rel-cage motor, but the belt shouldthen be spliced with take-up againstthe minimum stop in its travel.This leaves all of take-up movementfor belt stretch. Bumpers must beprovided to cushion take-up carriagewhen it strikes its minimum stop
during starting period. No run-inperiod is necessary before final vul-canized splice is made.
“Across-line” start. Run-in periodprovided. Movement B can alsoapply when “across-the-line” orreduced-voltage starting with a squir-rel-cage motor is used, and it is pos-sible to run belt for 2 or 3 days to aweek with metal fasteners before finalvulcanized splice is made. Whenmaking this splice, take-up can bepositioned to leave approximately3/4 of its travel for belt stretch.Intermediate movement B - C -Slope belt. Controlled start. Norun-in period. Take-up near lowerend. With some slope belts wheretake-up is at lower end, less thanusual amounts of take-up movementare satisfactory: an amount midwaybetween B and C can be used. Thus,for a fabric belt on 1000 ft. centers,13 ft. movement can be provided.With a slope belt where drive is atupper end, take-up is sometimesobtained by mounting lower terminalpulley on a carriage or by placing avertically-or horizontally-operatedtake-up in return belt strand nearlower terminal pulley. The take-upfor a slope belt will operate satisfac-torily near lower end when belt returnslope tension approaches or exceedsslack-side tension necessary to permitdrive to function properly. For slopebelts of this type, controlled startingusually is employed. The final vul-canized splice can be made so take-
up is positioned to leave approxi-mately 3/4 of its travel for beltstretch. No run-in period is neces-sary.
Movement C - “Across-line” start.Run-in period provided. The rela-tively small amounts of take-upmovement shown under movement Care used at the operator’s risk. Whenthese minimum amounts of take-upare provided, there is always achance that the belt will have to becut and respliced sooner than usuallywould be expected. When there is noother way out, these small amounts oftake-up movement can be used if thestarting torque is limited to 130% or140% of operating torque, and belt isgiven an ample run-in period withfasteners before making final vulcan-ized splice. The take-up must thenbe against the minimum stop in itstravel when final splice is made.Bumpers should be provided betweencarriage and its minimum stop.These conditions are applicable for aslope belt.
“Across-line” start. Run-in periodprovided. Initial tension in belt. Ifthere is “across-the-line” or reduced-voltage starting with a squirrel-cagemotor, and these minimum amountsof take-up must be used, a run-inperiod with a metal-fastened spliceshould be specified. The final vul-canized splice should then be madewith belt cut 1/4 of 1% short ofminimum tape-line measurement(belt length with take-up against itsminimum stop). After the run-inperiod, this final vulcanized splicemeasurement places belt on unit withsome initial tension applied. Forinstance, a 400-ft. belt would be cut 1ft. short of minimum tape-line mea-surement before making final vulcan-ized splice.
“Across-line” start. No run-inperiod. Initial tension in belt.With “across-the-line” or standardtype of reduced-voltage starting witha squirrel-cage motor, and assumingthat no run-in period may be possibleor convenient, final vulcanized splicecan be made with a belt length 1/2of 1% short of minimum tape-linemeasurement (belt length with take-up against its minimum stop).Thus, a 400-ft. belt would be cut 2 ft.short of minimum tape-line measure-ment.
4
TABLE 1 - RECOMMENDED TAKE-UP PROVISIONS
ConveyorCenters (Ft.)
ConveyorCenters (Ft.)“A” “A”“B” “B”“C” “C”
50100200300500700
100015002000250030003500400045005000
The recommended take-up travel is shown in above tabulation. If screw or fixed type oftake-up is used, at least the travel values shown in the C column are recommended andmechanical fasteners would generally be used. With vulcanized splices, the valuesshown in columns A or B can be recommended.
50100200300500700
100015002000250030003500400045005000
1-1/23681418253440475459647075
1-1/23571013182530353942454850
1-1/23571013182530353942454850
1-1/22-1/24-1/26911152125293235373940
111-1/22-1/24581115192326303438
111-1/22-1/24581115192225272930
Movement Movement
APPLICATION OF TABLE 1FOR REDUCED PLY BELTS
Due to the elastic qualities of nylon,belts are considered separately. Therequired take-up movement when vul-canized splices are used should bethat in column A. Take-up positionfor these belts is recommended as fol-lows:
With gravity take-up - Splice withtake-up at minimum point of its trav-el.
With screw take-up and mechanicalsplice - Splice with take-up at mini-mum point of its travel.
*With screw take-up and if vulcan-ized splice is used - If belt operatesat less than 50% of its rated tension,splice with take-up at minimum. Ifbelt operates at 50% or more of itsrated tension, splice with a belt length1/4 of 1% short which provides someinitial tension.
Take-up design: This has an impor-tant influence on belt stretching forwhich allowance must be made insplicing. Fig. A shows a standardvertical take-up with 180 degreeswrap-around pulley. When locatednear the drive pulley, this type pro-vides quickest action in absorbing beltstretch. Two strands of belting sup-port take-up weight. Pull on eachstrand is found by dividing take-upweight, including pulley and take-upframe, by A. For uniformity of ten-sion, both belt strands must be verti-cal.
Figure B shows take-up pulleymounted on a carriage, with tensionsupplied from a weight-supportingcable. This can be used as tail pulleytake-up where space limitationsdemand, or mounted under conveyorstructure at some other convenientlocation. To find pull on each beltstrand when carriage moves horizon-tally: subtract 10% of combined pul-ley and carriage weight from take-upweight and divide the resulting figureby A. When movement is on incline,slope effect of pulley and carriageweight must be included, and isdependent on angle of incline.
Fig. A - Standard vertical take-up.
Fig.B - Carriage take-up, shown as tail pulleyhorizontal take-up.
Calculating take-up weight: Anestimated take-up weight can be cal-culated from conveyor motor horse-power. Usually motor is 10 to 50percent or more above power normal-ly required, so that this calculationcould result in an oversize take-upweight. However, an oversize weightoften is necessary to lessen belt sagbetween idlers.
TABLE 2 - VALUE OF K FORAUTOMATIC TYPE TAKE-UPS
Take-up weight = 2T2, where theeffect of pulley and take-up frameweights are included as part of take-up weight.
Belt roll length and diameter -Formula for belt length and roll diam-eters are as follows:
Roll Diameter = D = 15 LT + 2.0”
Ball Length = L = (D - 2)2 or D2 -d2
15T 15.3T
Where D = Roll outside diameter in inchesL = Length of belting in feetT = Belt thickness in inchesd = Shell diameter in inches
Materials,tools &equipmentTable 3 provides the correct splicematerial grade to be used on allReduced Ply conveyor belts.Approved alternate selections areshown where possible. If only onegrade is shown - no substitution isallowed.
In addition, a splice kit computationtable and example is shown to assistyou in estimating the correct amountof material required.
MaterialsAs stated previously, the properselection and use of fresh materials isa must to making a good vulcanizedsplice. The main components ofsplicing materials are listed belowwith their proper use shown.
1. Cover stock - Uncured rubberused to rebuild the belt covers in thefill-in area of a splice or makingcover repairs.
2. Fill-in fabric - Uncured fabric,frictioned with rubber compound andused to cover the seam created bymaking a step splice.
3. Tie gum - Uncured rubber usedto replace skim coat stock in thesplice area.
4. Breaker fabric - Uncured break-er fabric, frictioned or coated withcompound for replacement of breakerplies or used as fill-in fabric in thesplice area.
5. Cements and solvents - Used tobond component parts together andenhance vulcanization of the splice
5
Type ofdrive
Single-PulleySnubbed-
pulley
Dual-pulley
180 o
200210220230240
360380400420460
0.500.420.380.350.320.30
0.1250.1080.0950.0840.064
0.840.720.670.620.580.540.260.230.210.190.15
HP X 33,000Belt speed, FPM Te = = Effective tension
T2 = K X Te = Theoretical slack-side tension required to drive belt
K2 = Factor taken from Table 2T1 = Te + T2 = Tight-side or
maximum tension
Total angle ofwrap on
drive pulleys
K-Factor
Lagged Bars
o
o
o
o
o
o
o
o
o
o
o
o
area.
Accessory materials1. Holland cloth - Used betweenthe surface of the new splicing mate-rials and the platens of the vulcanizerto resist sticking of material duringcure and provide a smooth surface.
2. Edge seals - Cement type materi-als used to dress the edge of cut edgebelting to give a finished appearance.
Steps requiredfor estimate1. Consult recommended splice mate-rial usage Table 3 to determine gradeof material required.
2. See Table 4 to determine correctstep length based on belt construc-tion.
3. Use Table 5 to determine theamounts of material needed basedupon the step length and number ofplies, using the formula for eachitem.
6
TABLE 3 - RECOMMENDED SPLICE MATERIAL USAGE
1 = Recommended 2 = Substitution � = Not Recommended
CoverGrade
SBRNit.
GradeCSHB
EPBNI
WNI(FDA)
CSHB
EPFRBNIWNI
Nat. Rbr.Neoprene
SBRButyl
EPDMSBR-FR
Nitrile (Black)Nitrile (White)
Grade CGrade SGrade HGrade B
Grade EPGrade FRGrade BNIGrade WNI
CSHBBC
BNIWNI
B636/637SHBB
B636/637BNIWNI
HI-TSHBB
HI-TBNIWBI
R-587-TR-587-TR-587-TR-587-TR-587-TR-587-T
MIBKMIBK
12�
�
�
�
�
12�
�
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1�
�
�
2�
�
2�
�
�
11
�
1�
�
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�
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�
1�
�
�
�
�
�
�
12�
�
�
�
�
21�
�
12�
�
�
�
1
�
2�
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�
1�
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1�
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1�
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1�
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Nat.Rbr. NitrileSBR Neop. Hot
SBR Butyl EPDM CokeSBR Nitrile SBR
Neop.SBRNit. SBR
General Purpose
Splice Kit Cover Stock Fill-in Fabric Cement Tie Gum Solvent
Oil Service Elevated Temperature Fire Resistant
Expiration DatesWARNING: Care must be taken to assure the propergrade of materials is used in all splices and that only freshmaterials are used within their recommended shelf life.Listed below is a general guide for your use. Refrigerationat 50 degrees F (10 degrees C) will greatly extend the shelflife of these materials.
Grade “C”, “B”, “EP” Materials
Grade “H”, “HI-T”, “S”, “WNI”, “BNI” Materials
Grade “BNI”, “WNI”, Cements
All Other Cements
12 Months
6 Months
3 Months
6 Months
Estimating material requirementsListed below is a computation table that gives the quantities of the various items requiredfor various width belts. The tie gum and cover gauges need to be established to match thebelt being spliced.Select belt cover gauges to match those required for the belt to be spliced. For example,for 3/16 X 1/16, order 3/16 and 1/16. If a breaker is being used, subtract the breakergauge when using multiwarp #12, subtract .032 (1/32) from the cover gauge. For exam-ple, 1/8 X 1/16 covers, order 3/32 X 1/32 covers.
WIDTH36”
36”
36”
48”
48”
48”
60”
60”
60”
72”
72”
72”
2
3
4
2
3
4
2
3
4
2
3
4
1 Qt.
2 Qt.
2 Qt.
2 Qt.
3 Qt.
4 Qt.
3 Qt.
4 Qt.
5 Qt.
3 Qt.
4 Qt.
6 Qt.
1 RL.
1 RL.
1 RL
1 RL.
2 RL.
2 RL.
2 RL.
2 RL.
2 RL.
2 RL.
3 RL.
3 RL.
1 RL./1 RL.
1 RL./1 RL.
1 RL./1 RL.
1 RL./1 RL.
1 RL./1 RL.
1 RL./1 RL.
1 RL./1 RL.
1 RL./1 RL.
1 RL./1 RL.
1 RL./1 RL.
1 RL./1RL.
1 RL./1 RL.
1 RL.
1 RL.
1 RL.
1 RL.
2 RL.
2 RL.
2 RL.
2 RL.
2 RL.
2 RL.
2 RL.
2 RL.
PLIES CEMENTS TIE GUM COVER BREAKER
7
Glass: 43
Cotton: 28 oz.32 oz.
6”6”
.010”
.010”
Multiwarp #12*Multiwarp #12*
Multiwarp #12*Multiwarp #12*
Cement
Tie Gum
*Cover STK
BRK/FILL-IN
.50
.31
.75
.47
1.0
.63
1.25
.78
1.5
.94
.75
.41
1.25
.50
1.87
.75
2.50
1.0
3.13
1.25
3.75
1.50
1.75
.59
2.62
.89
3.5
1.19
4.37
1.48
10.50
2.91
2.0
.69
3.00
1.03
4.00
1.38
5.0
1.72
5.25
1.78
2.50
.78
3.75
1.17
5.00
1.56
6.25
1.95
6.0
2.06
3.00
.87
4.50
1.31
6.00
1.75
7.5
2.19
7.5
2.34
3.50
.97
5.25
1.45
7.00
1.94
8.75
2.4
9.0
2.63
1.13
.61
1.50
.82
1.87
1.02
2.25
1.22
0.225 or 0.450 SEE NOTE
1.00 FOR ALL BELTS
9” Step Length
Cement
Tie Gum
*Cover STK
BRK/FILL-IN
0.225 or 0.450 SEE NOTE
1.00 FOR ALL BELTS
12” Step Length
0.225 or 0.450 SEE NOTE
1.00 FOR ALL BELTS
15” Step Length
0.225 or 0.450 SEE NOTE
1.00 FOR ALL BELTS
18” Step Length
0.225 or 0.450 SEE NOTE
1.00 FOR ALL BELTS
Cement
Tie Gum
*Cover STK
BRK/FILL-IN
Cement
Tie Gum
*Cover STK
BRK/FILL-IN
Cement
Tie Gum
*Cover STK
BRK/FILL-IN
Multiwarp #12*Multiwarp #12*
Multiwarp #12*Multiwarp #12*
Multiwarp #12*Multiwarp #12*
Multiwarp #12*Multiwarp #12*
6” .010”
Multiwarp #12*
Multiwarp #12*
Multiwarp #12*
Multiwarp #12*Multiwarp #12*
Multiwarp #12*
Multiwarp #12*
Multiwarp #12*
Multiwarp 200
6”6”
.010”
.010”
6”6”
.010”
.010”
9” .010”
12” .010”
12” .020”
12” .020”
12”12”
.020”
.020”12”12”12”
.020”
.020”
.020”15” .020”
PCB: 3543
MP: 35, 4350, 60
MP: 70
PN: 90-120
+PN: 110(S)
+PN: 110(H)
Style MH XH XXH
+ Style 220330,440,550,660300,450,600+PN: 150(S)
15” .020”+PN: 110(H)
15” .020”PN: 155
18”18”
.020”
.020”PN: 195, 200
24018” .020”+Grade: 200
*Belts with 1/32” or less covers require light 011 replacingMultiwarp fill-in fabric.
Note: + Cover Stock value to be 0.450 for these items usingreduced ply fabrics.
Steps Required for Estimates - For Multiple Splices
Estimating Textile Belt Material Splice Requirements
1.
2.
Consult recommended splice material usage Table todetermine the grade of material required.
See Table 1 to determine correct step length based on beltconstruction.
Qty. (TotalReq’d) =
Table 4 - Splice Kit Computation Table 5- Materials FactorConstruction Step
LengthBreaker/Fill-inFabric Type
Tie GumGauge
No. ofPlies 2 3 4 5 6 7 8 9
6” Step Length
*Multiplication factor is 1.25 for 3 or more splice kits. All quantities are rounded to next nearest whole number toassure enough material.
Tables 1 & 2Value foreach item
XWidthbelt ininches
36(constant)
No. ofsplices
required
*Multiplicationfactor for totalsplices required
X X
3. Use Table 2 to determine the amounts of materialneeded based upon the step length and number ofplies, using the formula for each item.
o
o
8
Example:Splice kit required for: 3 splices 48” 3 ply 330 RMAII 3/8 x 1/8 belt coversStep length - from Table 4 = 12”Materials factor - from Table 5 = A. Cement 1.50, B. Tie Gum 0.82,
C. Cover Stock 0.450, D. /Fill-in 1.00,E. Solvent (equals 4 x amount of cement)
A. CEMENT - Must be in full quarts for two part cements (C636, C637) itmust be an even number of each that added together equals the required total.Consult Table 3.
Qty. = 1.50 x x 3 x 1.25 = 7.5 or 8 Qts. =
B. TIE GUM - The amount is in cans of tie gum 9” wide x 16’ long. The cor-rect gauge is selected from Table 3. Consult 2020-B Hvy.
Qty. = 0.82 x x 3 x 1.25 = 4.1 or 4 cans = 4 cans .020” gauge, grade HiT.
C. COVER STOCK - The amount is in rolls of cover stock 18” wide x 2-1/2yards long. The correct top cover and bottom cover gauge and the amount requiredfor both covers must be calculated. Correct grade is obtained from Table 3.
NOTE: The gauge ordered is always 1/32” less than the actual gauge per coverunless the original gauge is 1/32” or less.
If the cover gauge is thicker than those available, a combination of the availablegauges is made to add up to the required gauge and the amount of rolls ordered cor-respondingly.
3/8 Top = 12/32 - 1/32 = 11/32 1/8 Bottom = 4/32 - 1/32 = 3/32
Cover Qty. = 0.450 x x 3 x 1.25 = 2.25 or 2 cans =
(1) Required for proper top gauge would be: 2 rolls 3/16”, 2 rolls 1/8” and2 rolls 1/32” to equal 11/32” required.
(2) For bottom gauge would be: 2 rolls 1/16” and 2 rolls 1/32” to equal 3/32”required.
D. BRK/FILL-IN FABRIC - For correct type see Table 3. The amount is thesame with or without breakers in the covers and is in rolls: 9” wide x 2-1/2yards long for top cover gauge 1/16” and over. For longitudinal/nylon with cov-ers of 1/32” or less divide the amount in half and provide light (611) 1-1/4” widex 2-1/2 yard rolls.
Qty. = 1.00 x x 3 x 1.25 = 4.9 or 5 rolls = 5 rolls #12 fill-in fabric,9” x 2-1/2 yds. required
E. SOLVENT - Must be in full quarts. Equal to 0.4 x total amount of cement.
Qty. = 0.4 x 7.5 = 3 Qts. required.
48”36”
(1.33)
48”36”
(1.33)
48”36”
(1.33)
48”36”
(1.33)
4 Qts. C6364 Qts. C637
required
2 rolls Grade C 3/16”2 rolls Grade C 1/8”2 rolls Grade C 1/16”4 rolls Grade C 1/32”
required
Steel cable materialsMost materials used in steel cablebelting are special makeup items andare produced for each individual splice.The basic materials are listed.
1. Sheeted cable gum - Specialrubber compounded to maximizeadhesion of the rubber to the cablestrength members.
2. Steel cable belting splicing fab-ric - Specially frictioned impactplies for use in the splice area to tieinto the existing portions of the belting.
3. Cover stock - Uncured rubber torebuild the covers in the splice area.
4. Miscellaneous - In addition.Breakers, film, micadust, replacementcable and fill-in fabric is available ifrequired.
1. Mill knife with two interchangeable blades.Use: cutting belt cover, etc. **2. Bevel-point knife 1” wide. Use: Skiving,cutting fabric, trimming rubber sheet.3. Half-round or round-end knife 1” wide.Use: Trimming rubber and fabric.*4. One-ply knife, offset type . Use: Cuttingheavy fabric in belt. Hook-like tip cuts onlyone ply thickness in single pass across exposedfabric.5. Combination one-ply knife and light prod-der. Use: Cutting light fabric in belt, one plyat a time. Prying loose fabric and rubber inbelt.6. Awl: Use: Puncturing air bubbles trappedunder rubber.**7. Prodder. A tool having a blunt, chisel-likeblade. Use: Loosening of plies and rubber.Forcing edges of patches, etc., into place.8. Two-inch roller. Use: Forcing fabric andsheet rubber into good contact with surfaces towhich they are applied.9. Stitcher having toothed wheel 2” in diame-ter. Use: Forcing edges of cover stock, etc.,into place.*These one-ply knives are available with hook
sizes to fit the high tension fabrics. Availablesizes - .065, .080, .100.10. Pincers. These are familiar carpenter’sclaw-type 8” long. Use: Pulling cover, fabricloose from belt. Before using, file jaws toremove sharpness at edges, corners. Wraphandles with tape for better grip.11. Scissors. Heavy-duty 10” size. Use:Cutting and trimming fabric, cover stock, etc.
Additional tools not shown here thatwill be useful:A 50-ft. steel tape marked in feet andinches.An 8-ft. steel rule.Thickness calipers.Counter or dusting brush.Cable cutters (steel cable belt).A 2” paint brush for spreadingcement.White or silver pencil for markingbelt.
Chalk line and chalk.Work gloves for safety.To keep edged tools working effi-ciently, have sharpening equipmenthandy. Many belt splicers sharpenknives on No. 00 emery cloth laid ona piece of scrap belting or cementedto a piece fastened to the bench top.For sharpening one-ply knives, use afine-grit triangular abrasive stone 6”long and about 1/2” on a face.(See Photo)
9
STEEL CABLE SPLICE MATERIAL QUANTITY ESTIMATESBELT PIW NO.
B636/B637 Cements, QuartsMultiply width of belt X thisfactor and double amount
R-587-T Solvent, QuartsMultiply width of belt Xthis factor
Grade HI-T Cable GumBelt width + 2”Gauge, inches
Yards per splice
Cover-Grade CBelt width + 2”Yards/Per SpliceTopBottom
.108
.117
.105”5
2-1/22-1/2
.117
.117
.120”5-1/2
2-3/42-3/4
.125
.133
.145”6
33
.142
.150
.170”7
3-1/23-1/2
Noodles 1/8” x 14”Belt width X 2 X Length of Splice in Feet
Holland Cloth - 1 yard per splice or minimum of 10 yards per orderThixon OSN2 - Steel Cable Primer - 1 gal./Splice
800, 10001050 1150, 1400 1700, 1800
2100, 24002700, 28003500, 3900
Tools for splicing and repair
Sharpening a one-ply knife.
TABLE 6ONE-PLY KNIFE RECOMMENDATION
Knife NumberK421
Offset Knife
K421 - .065
K421 - .080
PCB, MP - Multiple PlyPN - Polyester-Nylon Fabric
32 oz.,
35 oz.,
PN90, PN120Flexseal MPN110Flexseal H
PN150PN155PN195PN200PN240Flexseal XH, XXH,200
MP35, PCB35MP43, PCB43MP50MP60MP70
Belt Construction
Curing splice in vulcanizer Vulcanizer: Because most conveyorbelt splicing is done on the job,portable, electrically-heated vulcaniz-ers are used.
Caution: As a safety measure, checkvulcanizer for electrical grounds.Always make sure that both platensare grounded with heavy copper cablebefore turning on power. Some con-necting cords have a built-in thirdwire for grounding. Warning - fail-ure to follow instructions could resultin bodily injury or death.
Check power supply to make sure itis correct voltage and type for vulcan-izer. Serious vulcanizer damage canresult from incorrect voltage and typeof current.
Heat vulcanizer to 287 degrees F.Position it over top fill-in for firstheat.
Tighten clamping nuts on vulcanizerby hand; do not use a wrench at thispoint. Tighten each nut for a total ofone turn only, after resistance is felt.
Place edge irons against belt edges.Wedges or clamps can be used toobtain edge pressure.
Now tighten clamping nuts. Use onlythe wrench furnished with vulcanizer.With normal pull, wrench has lever-age sufficient to produce desired pres-
sure over platen area (around 100 to125 psi). In tightening, give each nutin succession a half-turn or less.
For curing belt splice, block in withedge irons to a thickness selected togauge less than belt gauge by follow-ing amounts.
Check wedges or clamps exertingpressure on edge irons, to make surethey are tight and that edge pressureis correct.
Place a protecting cover over vulcan-izer to reduce heat loss, especiallyaround platen edges. On a cold,windy day, such loss can be so greatthat rubber will not be completelycured at edges.
Only vulcanizers having two heatedplatens are recommended for curingsplices.
You can obtain further details of vul-canizer handling from vulcanizermanufacturer’s instruction manual.
Curing schedule: Curing timedepends on belt thickness, type ofvulcanizer, and type of rubber com-pound. The following table of curingtimes can be used for either splicingor repairing. (See Table 7)
Turn vulcanizer on before starting toassemble splice. Let platens heat to287 degrees F. After vulcanizer isclamped on belt, platen temperaturewill drop. Let it return to 287 degreesbefore starting to time period of cur-ing. The curing temperature (287F)must be maintained throughout time ofvulcanization. If temperature drops,allow more curing time; if it rises, ashorter time will do. (See Table 8)
Undercuring, overcuring:Undercured rubber is soft and lacksresilience. A simple test: Press endof screwdriver into rubber. If inden-tation remains, rubber probably isundercured, and additional time invulcanizer is needed.
Overcuring, up to a degree, is indi-cated by too much hardness as com-pared with rest of belt rubber.Extreme overcuring can cause soften-ing (known as reversion) whichbecomes worse if further curing isattempted.If edges of vulcanizer platens are notup to temperature, the rubber may beundercured in that region. When yoususpect this condition, allow an extra5 to 10 minutes of curing time over
10
Fig. A - Use of wedges to provide pressure onbelt edges during curing.
TABLE 7 - CURING TIME FOR CONVEYOR BELTING
Fig. B - Bolts used instead of wedges forapplying pressure to belt edges during vulcan-ization.
Belt ThicknessUp to 1/4”1/4” to 1/2”1/2” & over
1/64”1/32”1/16”
Iron gauge - less
GRADE I & II(IN MINUTES AT 287 deg. f)
Thickness of Beltor Repair Depth
1 HeatedPlaten
2 HeatedPlatens 1 Heated
Platen2 HeatedPlatens
2 HeatedPlatens
3/16” and less1/4”
5/16”3/8”
7/16”1/2”
9/16”5/8”
11/16”3/4”
343842
Use 2-platenpressabove5/16”
Over 3/4”: Add 2 minutes for each 1/16” of additional thickness. *This curing schedule isintended for portable vulcanizers under average field conditions. For Belt Repair Shopshaving permanent repair presses in heated buildings, the time can be reduced 5 minutesfrom the schedule shown for Natural or SBR.
23242526272829303132
505253
Use 2-platenpressabove5/16”
37394042434547484950
45464748484950515252
SCOFNITRILE OR NEOPRENE
(IN MINUTES AT 287 deg. f)EPDM (BUTYL)
(IN MINUTES AT 305 deg. f)
that indicated in Table 7. This doesno harm to work, yet assures com-plete curing at edges.If temperature of vulcanizer platens isabove or below 287 degrees F.: Forevery 5 degrees above 287, deductone-fifth of time that would be cor-rect for 287 degrees. For every 5degrees below 287, add one-fifth oftime that would be correct for 287degrees. Example: Curing for belt5/8” thick is 30 minutes at 287degrees.At 282 degrees, correct time would be
30 + 30 = 36 minutes5
At 292 degrees, time would be30 - 30 = 24 minutes
5Lowest vulcanizing temperature per-missible is 265 degrees F., highest is310 degrees F.
Overlapping heats: When vulcanizerplatens will not cover entire splice,two or more heats are necessary.Each heat should overlap precedingone about 1-1/2”. A common prac-tice is to cure top cover fill-in first,then proceed in overlapping stepstoward bottom cover fill-in. Whentwo vulcanizers are available, placeone over top cover fill-in, one at cen-ter of splice, and step both of them inthe same direction. When the vulcan-izer available will not cover the fill-inin one heat, we recommend that firstheat be made in the center of thesplice area, then proceed in overlap-ping steps toward the cover fill-ins.
Cooling splice: At temperatures usedin vulcanizing, rubber compounds losetensile strength. Therefore, allow beltsplice to cool to normal air tempera-ture before maximum belt tension is
applied. This is important when oper-ating tensions are 75 to 100 percent ofmaximum permissible tensions recom-mended by manufacturer. When youcan hold your hand on splice withoutdiscomfort, belt can be put into use.You can hasten cooling by runningwater over splice.
Blow-ups, blisters: A blow-up orblister that appears when platens areremoved is caused by moisture in beltor by air trapped in new material.Moisture may be water that was inbelt carcass, or in solvents used incleaning off skimcoat rubber.
To prevent blow-ups: Allow vulcan-izer platens to cool below steam tem-perature (212 degrees at sea level)before releasing platen pressure.
If a blow-up or blister does occur,repair work must be done in affectedarea. Simply reapplying vulcanizingheat and pressure will not remedy thecondition, for cement and tie gumalready have been vulcanized fullyand further curing treatment will notcause them to adhere.
Making avulcanizedstep splice
Conveyor or elevator beltThe following instructions are what isrequired to make a step splice in a con-veyor or elevator belt. The importantsteps are:1. Cutting the belt to proper length.2. Laying out the splice by measuringand drawing lines.3. Stepping down the belt ends.4. Applying splicing materials.5. Assembling the splice.6. Filling gaps lin top and bottomcover.7. Vulcanizing.
Cutting the beltto proper lengthFirst you must determine the totalamount of belting required to passcompletely around the conveyor systemwith the take-up in the proper position.In addition, you will require enoughadditional belting to produce the over-lap at the splice and to allow for trim-ming ends (and cutting all plies) on a22 degree bias angle. (See Fig. G)
To figure the additional length of belt-ing needed for a vulcanized splice, useTable 9.
Belt vulcanizedsplice lengthsThe following schedule for belt lengthrequired per vulcanized splice is basedupon a 22 degree splice angle (mea-sured by a lead equal to 0.4 beltwidth). The recommended splicingmethod for Reduced Ply belts is toremove the ply material from the stepsstarting at the end of the belt. Thisrequires an extra 6.0” at each belt endfor clamping which is in addition tothe normal 3.0” for trim.AL = SL(N - 1) + 0.4W + TA
AL = additional lengthN = number of plies in beltW = belt width in inchesSL = step length in inchesTA = allowance for 3” trim and
6” to clamp each end of beltto table or deck when required
11
TABLE 9 - VULCANIZED SPLICE - REQUIRED BELT LENGTH
Required Splice Length Without Lead - Inches Reqd. Lead Lgth.
Plies23456789
10
SL-6TA-3Formula: Splice Length = SL (N-1) + 0.4W + TA
SL = Step Lgth. In TA = Trim Allow., In. W = Wdth., In. N = No. Plies
SL-6TA-15
SL-9TA-15
SL-12TA-15
SL-18TA-15
Above lengths based on these step lengths & trim allowance.
1521273339455157
2733394551576369
3342516069788796
27395163758799111123
516987105123141159177
121824303642485460667278849096
5710121417192224262931343638
CottonGlassMP35
MP43MP50MP60
MP70PN90
PN110PN120
PN195PN240PN200
BeltWidth inInches
LeadLength
in inches
TABLE 8 - CURING TIME FOR PLYLOCK BELT JOINT
NATURAL RUBBER and SBR
Vulcanizer with2 Heated Platens
Vulcanizer with1 Heated Platen
Vulcanizer with2 Heated Platens
Vulcanizer with1 Heated Platen
OILPROOFLength of Heat - Minutes
Thickness of Belt
*We do not recommend use of single platen vulcanizer for Oilproof belts.
3/16” and under1/4”5/16”3/8”7/16”1/2”9/16”5/8”
11/16”3/4”
18192021222426272829
2426283031..........
37394042434547484950
5052535657..........
Direction of SpliceDirection a splice travels is not criti-cal for lightly-loaded belts operatingover large pulleys. But for installa-tions operating at or near full ratedbelt tensions, maximum splice lifecan be obtained only by runningsplices in the direction shown in thedrawings. When loaded, declined beltdrives the motor as a generator. Stepdirection should be opposite that rec-ommended when drive does thepulling.
The diagrams show steps positionedso the proper cover fill-in makes con-tact with drive pulley before anyother part of splice reaches it. Indual or tandem drive, splice is posi-tioned relative to drive pulley itreaches first (primary pulley).
MEDIUM TENSIONBELTINGCotton orpolyester-cottonblend (PCB)(without breaker)
These instructions are for cotton andpolyester-cotton blend fabrics, with-out breaker.
Laying outbelt endsLocating center lines: When layingout belt ends for stepping-down oper-ations, make all measurements from acenter line extending 15 to 20 ft.from each end of belt. Instead ofsimply drawing center line with beltedges as a guide, use followingmethod.
At intervals of 3 to 5 ft., mark centerpoints in belt width, using light col-ored chalk or pencil. Draw an aver-age center line with these points asguides.
Squaring ends: Before determining22 degree bias angle on portion to bestepped-down first, locate line estab-lishing square end of belt.
When belt edges are reasonablytrue: Place straight-edge along onebelt edge. Use carpenter’s square tomark line across belt at right anglesto straight-edge. Or you can placelong part of square directly againstbelt edge. Next, do same withrespect to other belt edge. If the twocross lines do not coincide, use amedian line (drawn halfway betweenthem) as guide in marking beltsquare. Squaring may also be donefrom an accurate center line.
When steel-square method cannot beused: At a distance from belt endequal to about 1-1/2 times belt width,drive an awl or small nail into belt atcenter line (point O, Fig. F). Usethis as a pivot for holding end of steel
tape. At point near present belt endwhere tape crosses belt edge, markpoint C on rubber and note distanceOC as indicated by tape. Keepingtape taut, swing it to intersect otherbelt edge. Mark point D, which mustbe same distance from pivot O aspoint C is. Line CD drawn acrossbelt will be square with center line.
Measuring and marking bias angle:When marking a vulcanized splice, abias angle of 22 degrees is used forcutting belt ends, plies, and covers.
Referring to Fig. G: Along line XC,measure back from C a distance equalto 0.4 x W, and mark point E. Drawa straight line connecting E and D.Angle EDC will be 22 degrees. Seephotos 1 and 2.
Marking reference, cutting lines:Along upper belt edge (Fig. G) mea-sure distance XE. To determine thisdistance, multiply length of each plystep by one less than the number ofplies, and add 5-1/2”. Example: Beltis 6-ply and steps are to be 6”, XE =6” (6 - 1) + 5-1/2” = 35-1/2”.
12
Fig. E - Locating belt center line. This lineis an “average” drawn with respect to anumber of center points established nearbelt ends.
Fig. G - Laying out belt ends to properbias angle, and establishing guide and cut-ting lines. Angle may run in either directiondepending on type rhombic platen.
Fig. A - Single drive contacting bottom sideof belt. Bottom-cover fill-in makes contactwith pulley before stepped region of splicereaches it.
Fig. B - Single-pulley drive contacting topside belt.
Fig. C - Two dual-drive arrangements con-tacting bottom side of belt. Step directionis with respect to primary drive pulley.
Fig. D - Dual or tandem drive with primarypulley contacting top side of belt.
Fig. F - A common method of squaringbelt ends. With O as a center, arc CD isdrawn to intersect belt edges or (whenedges are uneven) lines drawn near edgesand parallel to center line.
Make YD equal to XE. Draw refer-ence line XY. At X and Y, makesmall notches in belt edge to serve asreference points if line is rubbed off.Lay off and draw two more lines, GJand HK, parallel to XY at 2” inter-vals. See photos 3 and 4. (Disregardline IL at this time.) GJ and HK arecalled cover fill-in cutting lines.
As a check, lay out all cutting lines forply steps. Last step should have anextra 1-1/2” for trimming, making it7-1/2” long.
Trim end of belt to the 22 degree biasangle by cutting along line ED withmill knife held perpendicular to belt.See photo 5.
Marking other belt end: Placemarked end over other (second) beltend, and align the two ends carefullywith aid of previously-drawn centerlines. If layout was made on topcover, place this surface in contactwith back cover of other end.Transfer positions of reference notch-es. Mark along belt end you just cutto a 22 degree bias: this line becomesreference line for second end. Whereit intersects edges, make referencenotches to serve as guides in layingout cutting lines for back cover fill-inand ply steps. Points opposite refer-ence notches of first end determinebias angle of second end. Draw lineconnecting these points, and cut sec-
ond end along this line.
Making coverfill-in cuts1 - With mill knife held at 45 degreeangle, make first cover fill-in cutalong line GJ (Fig. 11 and Photo 6).This cut is No. 1 in Fig. 12. Cut-edge of rubber cover should appear asat a, Fig. 13. In some cases whereservice conditions are severe, andcover is heavy (over 1/4”), leadingedge of top cover fill-in is undercut,as at b in Fig. 13. Cut only to firstply of fabric, not into or through it;you can feel knife point touching fab-ric. Or you can cut almost to fabric,and tear rubber rest of way whenremoving fill-in strip.
2 - With mill knife held vertically, cutalong line HK through rubber cover tofirst fabric ply. See Photo 7.
13
Fig. 13 - Section through fill-in area showinghow belt cover may be beveled or undercut.
3 - Between and at right angles to thetwo cuts just made across belt, cutthrough top cover to fabric parallel toand 1/4” from each belt edge. Such1/4” strips are left so edges of beltwill not be damaged during subse-quent stripping of cover and plies.See Photo 8.
4 - Aided by prodder and pincers,loosen cover and strip it from areainside cuts. This exposes top fabricply. If you have difficulty pulling fill-in area strip free, cut it along center
so you can strip off half at a time.See Photo 9.
Stepping-downbelt endsThis process consists of cutting andstripping off sections of successivefabric or cord plies in such a way thatexposed portions remaining form aseries of steps.
1 - With mill knife, make a verticalcut parallel to and 1/4” from each beltedge, and extending from cover fill-incut to end of belt. Blade should pene-trate cover and first fabric ply. See Photo 10.
2 - With one-ply knife, cut throughfirst fabric ply along line of last trans-verse cut you made through cover(Cut No. 2 along line HK, Fig. H andPhoto 11).
The one-ply knife has a hooked tipwhich, at a single pass, will cutthrough one thickness of fabric. Pressfirmly but not excessively hard. Donot make a repeat cut unless it is nec-
essary, then use extreme care or youmay damage next ply. See photo 12.
14
Fig H - Stepping down fabric belt that has no breaker
15
3 - With prodder, break through skimcoat beneath the cut fabric ply on sideof cut toward belt end. Loosen about1/2” of ply across width of belt. Thisenables you to grip ply and attachedcover with pincers. When prodding,be careful not to damage fabric ornext ply. See Photo 13
4 - Strip off top cover and first fabricply from fill-in to end of belt.Standard widths of 4” can be handpulled and are recommended. So,before pulling, make cuts 4” apart,parallel to belt edges and extending
through cover and first ply only. Ifyou cannot judge when knife bladehas penetrated first ply, you can cutthrough cover only, and make addi-tional light passes to score fabric so itwill rip. Alternate way: Strip offcover. Use one-ply knife to cut
through fabric. With pincers, griploosened end of each fabric strip andpull it free. Pull off skim-coat rubberalong with fabric so ply beneath willbe bare. See Photo 14
5 - With bevel-point or round-noseknife, trim off strips remaining alongbelt edges, so belt is smooth and levelall the way across. See Photo 15
6 - By measuring from referencenotches, mark ends of cutting line forforming step in second ply. SeePhoto 16. This step will be 6” long,and cutting line will be 10” from ref-erence line (Fig. H: line marked “CutNo. 3”).
7 - With one-ply knife, cut along lineestablished in preceding operation.See Photo 17. Cut through one fabricply only. Also cut through same plyalong lines 1/4” from each belt edge
and extending to end of belt.
8 - With prodder, break through skimcoat under portion of ply to beremoved. Loosen it from underlyingfabric for a distance of 1/2”, or so,from transverse cut. See Photo 18.
9 - For easier ply removal, make sev-eral lengthwise cuts with one-ply knifeso fabric and attached skim coat canbe pulled off in strips.
10 - Strip off loosened ply fabric andskim-coat rubber adhering to it.See Photo 19.
11 - Trim edges as before to makebelt level all the way across.
16
12 - Measure from reference points tolocate cutting line for next step. (CutNo. 4, Fig. H) Cut through fabricwith one-ply knife, including cuts1/4” from edges. Strip fabric and itsadhering skim coat from underlyingply and trim edges, as for precedingsteps.
13 - Use same procedure for eachsucceeding step, until all plies areexposed. See Photo 20. Steps willlook like this: First ply step directlyunder the cover is 2” long (includingportion covered by bevel along cutedge of cover). The next (second ply)step, and all remaining steps are 6”long, except last step which measures7-1/2” to provide 1-1/2” for trimmingwhen splice is fitted together.
Cleaning andbuffing splice stepsUse prodder to remove any skim coatremaining on exposed piles. See
Photo 21. This is made easier by let-ting rubber solvent, applied in limitedquantity to the remaining skim coatonly, act on the rubber a few minutes.Because of danger of damaging fabric,a sharp-edged scraper, wire brush, orsimilar tool should not be used forremoving skim coat.
Buffing: Use coarse emery clothsuch as No. 1 or No. 2 to buff allsurfaces of fabric steps and bevelededges of cover. See Photo 22. Thiscleans off loose particles and raisesfabric nap so cement can produce astronger bond. Excessive buffingmay damage fabric enough to causelater failure.
Making cover fill-in - Measure 3-1/2”toward the splice from the belt end,line DE, and draw a cutting line.With mill knife at 45 degrees, cutalong this line, through cover only.Make similar vertical cuts parallel toand 1/4” from belt edges. Pull offstrip of cover. Trim edges flush withbelt. This work can also be doneafter the belt is fitted together asexplained on pages 22 and 23.
17
Stepping-downsecond endNext, step-down second end of belt.The procedure is the same as for firstend. There are two cutting lines cor-responding to GJ and HK in Fig. Gfor bottom-cover fill-in. These andreference lines XY are spaced at 2”intervals (Figs. J and L). First-plystep is 2” long, second and successivesteps are each 6” - with 1-1/2” addi-tional trim allowance on final stepnext to top cover.
Checking fit: After cleaning andbuffing second end, place belt endstogether to see if they fit properly.Each step should butt neatly againstcorresponding step in matching half ofsplice. There should be no overlap-ping, no gaps. If misfitting doesoccur, make corrections by propertrimming of plies. A good fit at thisstage assures a satisfactory splice.
Cementing: Stir thoroughly each canof splicing cement. If you are work-ing with Grade C cement, mix theNo. 636 and No. 637 portions togeth-er. Expose both stepped surfaces byturning back the belt end forminguppermost portions of splice. Apply aliberal coat of cement to both ends.See Photo 23. Brush thoroughly toassure good coverage and penetration.Coat all steps and cover fill-in areasup to end of 2” first ply step. Let drythoroughly. Drying can be hastenedby fanning to increase air circulation.Hot air, as from an electric hairdryer, is sometimes used. Heatshould not be sufficient to cause par-tial curing of cement.
Apply second coat of cement just asyou did the first. Let dry until tacky.
Applying tie gum: Determine proper
thickness of tie gum to use (See Table3, pg. 11)
Starting at 6” step nearest top cover,apply a 9”-wide strip of tie gum.Keep one edge of gum even with pro-jecting end of ply adjacent to cover;do not cover the 2” step in this ply.
See Photo 24. Leave polyethylenefilm on upper surface of gum. If nec-essary, wash tie gum with solvent toremove dirt or bloom or to increasetackiness, before applying it.
3 - Measure for cut through cover.
Fig. L - Details of bottom cover fill-in for fab-ric belt width 1/16” or heavier cover.
Fig. J - After being stepped-down, ends of fabric belt having no breaker should look like this.
18
With hand roller, force tie gum intogood contact with cemented surface.See Photo 25. Use awl to punctureany trapped air bubbles.
Apply successive strips of tie gum toremaining steps until all of splice areais covered.
Apply tie gum to only one belt end.
Fitting splicetogetherBefore removing any polyethylenefilm from tie gum surface that is tocome into contact with other half ofsplice, make another check to see ifsteps fit together neatly. Make sure,also, that center lines of both beltends are in alignment and continuestraight for some distance each wayfrom splice. Disregard differences inalignment of belt edges, for there maybe some variations in widths of thetwo ends.
When you are sure that steps fit prop-erly and center lines are in alignment,you can apply clamps a foot or sofrom stepped sections to prevent shift-ing of ends during final fitting.
Final fitting: Bend uppermost half ofsplice back on itself to expose steps.Then select one of the two followingmethods for final fitting:
1 - Narrow belt with five steps orless: Peel polyethylene film off sec-ond step from belt end and for 1”each way from this step. Positionupper half of splice over lower half.See Photo 26. They will adhere alongarea from which polyethylene filmwas removed. Roll and hammer beltto assure good adhesion.
Remove remainder of polyethylenefilm in direction of top cover fill-in.Bring splice surfaces carefully togeth-er, making sure that each step fitsproperly. See Photo 27.
Roll to assure good contact. SeePhoto 28.
2 - Wide, heavy belt of more thanfive steps: Remove polyethylene filmfrom middle step or from either stepnear middle when there is an evennumber, and for about 3” each way.Bring other half of splice into posi-tion. Roll exposed step into contact.Working toward top cover fill-in,remove polyethylene film from nextstep and 3” beyond. Fit and rollhalves of this step together, continueuntil fill-in is reached. This systempermits each step to be fitted individu-ally.
Cover fill-ins-1/16” thick orthicker coverAfter assembly of the ply steps, gapsremaining in top and bottom covershave to be filled in with new rubber.When belt has no breaker, these gapsare identical except that top coverusually is thicker. Marking a top-cover fill-in is described. For the bot-tom-cover fill-in the procedure is thesame, except where noted.
1 - If not already done, remove poly-ethylene film from tie gum over stepadjacent to fill-in area and over extrafabric that was allowed for trim. SeePhoto 29.
2 - Roll cover to force tie gum intogood contact with cemented surface ofmatching half of splice.
3 - Measure for cut through cover,and draw a straight guide line. Thisline is positioned so width of fill-inbetween edges of cover rubber will be4” (Fig. K). Line will be 6” fromreference line XY on top cover (Fig.G, line IL and Fig. J).
The covers at the belt ends may bestripped from the belt now or beforeas explained on page 21.
4 - With bevel-point knife at 45degree angle, cut along guide line IL.Blade must penetrate only to first fab-ric ply, not into it. See Photo 30.Cut-edge of rubber will appearbeveled as in Fig. H.
5 - Strip rubber cover from end of
belt ply. See Photo 31.
6 - With prodder, force fabric ply into
tight fit with matching end of ply inother splice half, and into good con-tact with ply below it. See Photo 32.Prodder makes crease in fabric alongjoint.
7 - Run bevel-point knife along creaseto trim off excess fabric. See Photo33.
8 - With coarse emery cloth, lightly
buff the fabric. Buff firmly thebeveled edge of cover rubber and topsurface of cover for about 1/2” backfrom fill-in area.
9 - Brush coat of cement over buffedarea, working it well into fabric, andlet dry. See Photo 34. Apply secondcoat and let dry until tacky.
10 - A longitudinal nylon cord breaker
shall be used over butt seams of out-side plies where there is no breaker inoriginal covers and covers are 1/16 ofan inch thick or thicker. Brush onecoat of cement on one surface of thisbreaker stock and allow to dry. Alsocut a strip of uncured cover stockslightly longer than and 1-1/2” widerthan the fill-in. Remove polyethylenefilm and brush coat of cement on sur-face it protected. Let cement dry.
11 - Place end of longitudinal nyloncord breaker, cemented side down,over fill-in area, starting 1/4” frombelt edge. Be sure that its cords runparallel to edge of belt. Roll fabricinto fill-in area. Use prodder to forcefabric tightly into corner. See Photo35. Cut off excess fabric flush withbottom edge of fill-in with a .065 one-ply knife. Fabric should not projectup on the skived cover cut. See Fig.K.
12 - Making butt seams in the longitu-
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Fig. K - Details of top fill-in for fabric beltthat has no breaker.
dinal nylon, lay fabric in the fill-inarea across the full width of the belt.See Photo 36. Trim the end so it is1/4” short of the belt edge.
13 - Place cover stock over; fill-in
area, cemented side down. Roll intogood contact. See Photo 37.
14 - With bevel-point knife, trim off
excess cover stock all around. SeePhoto 38. When two strips of coverstock are necessary to produce desiredfill-in thickness: Remove polyethylenefilm from second strip and apply onecoat of cement to uncovered surface atsame time you prepared first strip.After first strip is trimmed, washbloom from its exposed surface withcloth moistened with solvent. Place
second strip with its cemented surface
down. Roll firmly.
15 - With awl, make numerous holes
(spaced 1/2” each way) in uncuredcover stock, to let trapped air orsteam escape during vulcanization.See Photo 39. Extend awl holes onlyto depth of new material. Roll stockagain to force out trapped air.
16 - Brush light coat of cement over
fill-in area and one surface of a stripof holland cloth 1” wider than fill-in.
17 - Place holland cloth, cement-sidedown, over fill-in. See Photo 40.Trim it even with belt edges. Hollandlayer protects fill-in during handling,produces a smooth surface on rubber,and prevents fill-in from sticking tovulcanizer platen. Turn belt over andcomplete other cover fill-in in samemanner.
Cover fill-in 1/32” thick cover -1 - Cut 1-1/4” strip of light No. 611breaker fabric slightly longer than fill-in. Coat surfaces of this strip withcement. See Photo 41. Also cut astrip of uncured cover stock to samelength, and 1-1/2” wider than fill-in.Remove polyethylene film and brushcoat of cement on surface it protected.
20
Let cement dry (See Fig. L).
2 - Center breaker fabric over buttjoint in fabric ply. See Photo 42.Trim ends so they are 1/4” short ofbelt edges. Roll breaker fabric intofirm contact. Finish cover fill-in asdescribed.
Finishing edgesWhen a belt is wider at one end,edges will not be even when splice isassembled. If edges are not too badlyworn or cut, and width difference isnot great, try to fit them together sothey will require no further building-up or finishing.
1 - If edges must be renewed, trimthem so they are even and slightlyunder with respect to belt width.Amount they are undersize should beequivalent to the 1/16” to 1/8” thick-ness of cover stock to be applied.Buff edges with coarse emery cloth,
as shown. See Photo 43.2 - Brush two coats of cement on beltedges at splice, allowing each to dry.Brush one coat on strips of belt coverstock to be applied to edges.3 - Press cemented surfaces of rubberstock against belt edges. Roll intogood contact.4 - Trim strips flush with belt sur-faces, as illustrated in Photo 44. Roll
them again, thoroughly. Splice is now ready for curing in vul-canizer.
Splicing fabricbelt havingbreaker1 - Locate center line, square the ends,locate reference line (XY, Figs. G, M)- the same as for a belt without abreaker. Many of the subsequentoperations are like those for belts hav-
ing no breaker, but some are different.2 - Locating cutting lines. After locat-ing the reference points and lines,draw cover fill-in cutting line GJ 1”from XY, and line HK 2” from GJ(See Figs. G,M). (Line IL will bedrawn later.) Trim belt end to 22degree angle. Lay out ply steps as acheck.3 - Mark matching belt end asdescribed on page 18. Note that refer-ence line XY is same distance frombias-cut belt end whether or not thereis a breaker in cover on which XY isdrawn.4 - Making cover fill-in cuts. Make45 degree cut through cover along lineGJ. Make vertical cut through coveralong HK. Make cuts through coverparallel to and 1/4” from both beltedges. Strip out 2”-wide section ofcover, exposing transcord breaker fab-
ric. See Photo 45.5 - Stepping-down belt - Breaker step:Make cuts parallel to and 1/4” fromeach belt edge, through cover andbreaker and extending from line HK toend of belt. With one-ply knife, cutthrough breaker along line HK. Prodloose this edge of breaker and skimcoat under it. Strip off top cover andbreaker from line HK to belt end.Trim off 1/4” strips of cover andbreaker along belt edges.6 - First-ply step: Measure 4” fromreference line XY to locate line IL(Fig. G). With one-ply knife, cutalong this line (cut No. 3, Fig. M)through first fabric ply. Also cutthrough this ply 1/4” from belt edges,from IL to end of belt. Strip off fab-ric ply and skim coat under it from ILto belt end. Trim 1/4” strips frombelt edges to expose all of next ply.Step in first fabric ply is 1” long.7 - Second-ply step: Measure fromreference line XY a distance of 10” to
21
Fig. L - Details of bottom cover fill-in for cotton and polyester-cotton blend fabric belt with 1/32”cover.
locate cut for forming step in secondfabric ply (Cut No. 4, Fig. M). Thisis the first 6” step. Strip off unwantedfabric and skim coat, and trim edgesas before.8 - Remaining steps: Use same proce-dure for each remaining step, until allplies are exposed. Steps will look likethis: Breaker projects 2” beyondcover, measured from top surface ofcover at beveled edge (Fig.M). Firstfabric ply step directly under breakeris 1” long. Next (second-ply) step andall remaining steps are 6” long, exceptlast step which is 7-1/2” long to pro-vide 1-1/2” for final trimming.9 - Back cover fill-in cut: After belthas been stepped down, strip 3-1/2” ofback cover from the belt as describedfor belt having no breaker (pages 22and 23).10 - Second end: Next, step-downother half of splice. There is nobreaker ply next to bottom cover, soprocedure for this end is same as thatdescribed for belt having no breaker(page 19).11 - Top cover fill-in cut withtranscord breaker or breaker fabric:Measure 4-1/2” toward splice frombelt end, line ED, and draw cuttingline. With mill knife at 45 degree, cutalong this line, through cover only.Make similar vertical cuts parallel toand 1/4” from belt edges. Pull offstrip of cover. Mark a line acrossbreaker 2-1/2” from and parallel tobelt end line ED. Cut through breakerbut not into fabric ply. Strip offunwanted part of breaker. This leavesadjacent fabric ply, which, with trimallowance of 1-1/2”, is exposedapproximately 2-1/2”.12 - Cleaning, buffing, assemblingsteps: When belt has a breaker, this issame as described for belt withoutbreaker (page 21). When applying tiegum, cover splice area as far as shortstep of ply next to breaker (line IL inFig.G and Fig.M).13 - Top cover fill-in with transcordbreaker or breaker fabric: When abelt has a transcord breaker or breakerfabric beneath top cover, procedurefor making top cover fill-in differsfrom that for back cover fill-in. Firstremove polyethylene film fromremainder of tie gum adjacent to fill-inarea. Roll top cover to force tie gumagainst cemented surfaces as far as endof first ply step in fill-in area. Withprodder force this ply into good con-duct with next ply. Cut off projectingportion of fabric. Roll down remain-
der to form neat butt joint. Fill-inshould appear as in Fig.N.14 - Buff fabric and rubber. Applytwo coats of cement. Let first coatdry thoroughly, second until tacky.15 - A longitudinal nylon cord break-er shall be used over butt seams ofoutside plies when there is a transcordbreaker or breaker fabric in the origi-nal covers. Brush one coat of cementon one surface of this breaker stockand allow to dry.16 - Place end piece of 9” wide longi-tudinal nylon breaker, cemented sidedown, over fill-in area. Be sure thatits cords run parallel to and start 1/4”from the belt edge. With a prodder orstitcher, force new longitudinal nylon
breaker into good contact with theoriginal breaker fabric. See Photo 46.17 - With bevel-point knife, trim lon-gitudinal nylon breaker so remainingpiece just fills gap in original breakeras in Photo 47. When 9” strips areused, two or more may be required tocover fill-in area. Trim ends of break-
er strip 1/4” from belt edges. Rollbreaker fabric into good contact.18 - Apply cement and uncured cover
22
Fig. M - Stepping-down fabric that has a breaker ply next to top cover.
Fig. N - Details of top cover fill-in for cotton and polyester-cotton blend fabric that has a breaker.
stock as already described (pages 23-24).
Splicing Butyland EPDM beltsSplicing instructions for Butyl andEPDM conveyor differ from a naturalrubber or SBR conveyor only in mate-rial used and temperature of the vul-canizer.
The butyl compounds used have char-acteristics that differ from other rubbercompounds. These extra precautionsshould be followed.
Materials - Butyl - Grade B materials.
EPDM - EPDM cover stock. Grade Btie gum and cement.
Solvent may be used for thinningcement, tackifying tie gum or coverstock or for cleaning the stepped downbelting carcass.
Butyl compounds have less tackinessthan other rubber compounds, espe-cially after aging. Under proper con-ditions, Grade B splicing materials areusable 6 months after processing.Check condition of splicing com-pounds before using.
Splice preparation
1. The fitted splice of a butyl belt canbe distorted more easily than one withrubber compounds. This is due to thefact that butyl splicing materials areless tacky than other compounds.Place belt and vulcanizer in such posi-tion on the supports to allow for mini-mum amount of bending or distortionas splice is moved into the vulcanizer.C-clamps can be used to hold ends inregister until ready for curing.
2. Grade B cement should be permit-ted to dry thoroughly before applyingthe Grade B tie gum.
3. After Grade B tie gum is appliedand rolled down into place, removethe polyethylene film backing in nar-row strips. This prevents pulling thetie gum loose from the cementedsteps.
Vulcanizing
1. Use 305 deg. F. vulcanizing tem-perature. Butyl compounds require ahigher vulcanizing temperature forbest results. To use 287 deg. F.
would require doubling the cure timeshown for 305 deg.
2. All heats should be given a cool-down to prevent possibilities of blistersor blow-ups. Allow vulcanizer platensto cool down to 240 deg. or belowbefore releasing platen pressure.
3. Use Holland or mylar film oversplice to prevent cover sticking topress platen.
SPLICING HIGHTENSION BELTSThe general splicing procedure is thesame shown for cotton and PCB fab-rics with these important modifica-tions.
Synthetic fabrics; rayon, nylon andpolyester, are given a special treatmentduring processing to provide increasedadhesion to the rubber compounds.This reddish brown colored treatmentmust not be removed in splicing.
The treated fabrics are harder andmore compact than cotton fabrics.This fact, plus the increased adhesion,makes the synthetic constructions moresusceptible to damage by the prodderat the step lines. A modified methodof stripping down the belt ends is rec-ommended to eliminate damage thatcould be caused by prodding to lift thelead edge of the plies in stripping.
Laying out: Square the belt end andlay out as shown in Fig. F and Gexcept allow 6” extra on each beltend. This extra length is used forclamping down the belt end forreverse stepping of the splice.
Cover fill-in cuts at belt end: Removecover fill-ins from the belt ends asdescribed on pages 21 and 27.
Stepping down:
1 - Clamp belt end.
2 - Remove cover with standard proce-dures.
3 - With one-ply knife of the propersize, cut the first step. Do not prodalong this cut.
4 - Make a rough cut at the belt endbeyond the step area and, with prodderor chisel, lift the first ply far enoughto attach a clamp and cable. Strip plyback to cut made for first step.
5 - Make cut for second step and again
strip back, working from the end ofbelt.
6 - Repeat until all plies stepped back.
7 - Remove the area containing therough cuts and prodded plies.
Cleaning and buffing: In most cases,the rubber skim coats will split andleave a layer of rubber on the synthet-ic fabric surfaces. It is only necessaryto buff this coating to insure removalof loose rubber particles and dirt. Donot buff any exposed fabric areas. If aheavy skim coat is left on some areasafter stripping, reduce its thickness bybuffing the rubber only to obtain aseven a pressure surface for the newcement and tie gum as possible.
1 - Layout: Belt layout is the same asalready described.
2 - Cutting steps: To prevent damageto underlying plies, steps should be cutwith the proper one-ply knife. SeePage 14 for recommendation.
3 - Cementing: Use Grade C(636/637) cements on all high tensionbelting. For belts of other qualtities,see Table 3 for recommended materi-als.
Mix Grade C (636/637) cements inaccordance with instructions given onthe container. Apply an even coat ofcement, brushing thoroughly to assuregood coverage and to eliminate areasof heavy cement deposition. Coat allsteps and cover fill-ins up to the endof the first ply step. Let dry thor-oughly. Apply a second coat and letdry until tacky.
4 - Applying tie gum: Determineproper thickness of Grade Hi-T tiegum to be used.
5 - Cover fill-ins: The longitudinalnylon cord breaker is used over thebutt joints of outside ply of the splicein the following areas.
A. Over butt seams of outside plieswhere there is no breaker in originalcovers and covers are 1/16” thick ormore (Fig. O).
B. As replacement of heavy breaker
23
fabric or transcord breakers originallyin covers and under the fill-in strip(Fig. P).
SPLICINGREDUCED PLYThe general splicing procedure is thesame as for high tension beltingexcept, with these important modifica-tions. The following instructionsapply to Reduced PLY.
Splice length: The determination ofthe additional length of belt needed forsplicing is explained on page 17.
Laying out: The layout for ReducedPly belts without and with breakers isthe same (Fig.Q). Note the 6”allowance left at each end to permitreverse stripping.
Removing cover at fill-in: At beltends remove cover and existing break-er where the cover fill-in is to belocated. Make a vertical cut along thebelt end, line ED, through the coverand existing breaker down to the ply.
At a distance of 5-1/2” from the beltend, make a 45 deg. cut parallel to thefirst cut. Make a vertical cut parallelto and 1/4” from each edge betweenthe two cuts. Cut through only thecover and existing breakers. Strip offall covers and existing breakers.
Stepping down:1 - Clamp belt end to splicing table orconveyor deck.
2 - Making cover fill-in cuts: Make a45 deg. cut along line G-J. See Fig.Qand vertical cut along line H-K, andremove cover and existing breakers asdescribed.
3 - Cutting RP plies: With a one-plyknife of the proper size, cut the firststep. Do not prod along the step line.Stripping is done in reverse.
4 - Reverse stripping: Make a rough,transverse cut in the first ply near theclamped end of the belt. The cutshould be outside the splice area, seeFig. Q, line D-E. With a prodder orchisel lift the ply far enough to attacha stripping clamp. Strip ply back tocut made at first step line.
5 - Repeat in case of 3- and 4-ply beltsuntil all plies have been stepped down.
6 - Remove clamp and cut off end ofbelt along line ED.
7 - Repeat same procedure for secondend of belt.
Cleaning and buffing: In most casessome rubber will be left on the fabricsteps. Buff these areas lightly toremove dirt and loose particles of rub-ber. Do not buff any exposed fabricareas.
Cementing: Use Grade C 636/637 (2part) cement (mixed according toinstructions on container) on all Grade
I, II belting. See Table 3 for othergrades.
Apply an even coat of cement on eachbelt end, brushing thoroughly to assuregood coverage. Coat entire splice areato the end of the first ply step. Cross-brush across width of belt to spreadout any accumulations of cementbetween fabric ribs. Let dry thor-
24
Fig. O - Details of fill-in for high tension belts without breaker.
Fig. P - Details of fill-in for high tension belts with breaker.
Fig. Q - Splice layout for Flexseal belts.
oughly - apply a second coat and letdry until tacky.
Applying tie gum: Starting at thestep line of the top ply, apply 9” widestrips of tie gum across entire splicearea. Do not cover 4” step in top ply.With hand roller, force tie gum intogood contact with cemented surface.Remove plastic film and apply a sec-ond (and, if necessary, a third) layerof tie gum. Total tie gum thicknessshould be about 0.020” (for rubberbelts, use two layers of 0.010”, or onelayer of 0.020” Grade Hi-T tie gum).For neoprene belts, use one layer of0.020” ga. or two layers of 0.010” ga.Grade S tie gum. Do not removeplastic film from last layer of tie gumapplied. Apply tie gum to only onebelt end.
Fitting splice together: Follow gen-eral instructions given on pages 22 and23.
Making cover fill-in: Make fill-in inaccordance with general instructionswith the following exceptions.
1 - See Fig. R for layout and dimen-sions of fill-in for RP belts without
breakers and Fig. S for RP belts withbreakers. The fill-in procedure is thesame for belts with or without breakerwith 1/16” or more thick cover. RPrequires minimum covers of 1/16” forvulcanized splices.
2 - After cementing fill-in area andallowing to dry, apply an 8” long stripof tie gum (.020” ga. Grade Hi-T forrubber belts, .020” ga. Grade S forneoprene) to the fill-in area.
3 - Use 9” wide strip of coatedMultiwarp fill-in fabric No. 12.Fabric is furnished cut on bias readyfor use. To increase tackiness, cementboth sides lightly and allow to dry.Roll fabric into fill-in area with warpcords parallel to edge of belt. Useprodder to force fabric tightly into cor-ners. Cut off excess fabric flush withbottom edges of fill-in area. Fabricshould not project up onto skivedcover cut (see Figures R and S). Fill-in fabric may be seamed.
4 - Cut a strip of .020” tie gum longenough to cover entire length of fill-inand 4” wide or half of the total fill-inwidth. Cover the area from the out-
side step line to the cover cut lineaway from the splice area. For rubberbelts use .020” Hi-T tie gum. ForNeoprene belts use .020” Grade S tiegum in both top and top and bottomcover fill-in strip. This equalizesthickness throughout entire splice area.
5 - Cut strip of uncured cover stocklong enough to cover entire length offill-in and about 9” wide. Use coverstock 1/32” thinner than original coverthickness - brush one side lightly withcorrect cement to increase tackiness.
6 - Apply strip of cover stock over theMultiwarp fill-in fabric and .020” tiegum and complete fill-in according toinstructions on pages 23-26.
7 - Finish belt as described.
STEEL CABLEBELTINGThe splicing of steel cable beltingrequires different tools and techniquesto do it properly.
Butt spliceA. Belt placement on table andestablishment of center line (See Table 10).
1. The vulcanizer bottom platen shouldbe flush with the table top, and locatedbetween the two end sections of thetable. With this type of setup, the beltcan remain in place between the side-boards on the table and thus retaingood alignment.
2. Place first belt end into position ontable. Entire length of splice areashould be over the work table (bottomplaten of vulcanizer). When belt is inproper position, approximately 18’ to20’ of belt will be laying on table iftable is similar to recommended type.
3. Establish center line of belt. (SeeTable 11).
a) Measure across width of belt at sixto seven points in length of belt on thetable, and mark the center at eachpoint of measurement.
b) At each of the center markings,measure to each edge of belt to checkexactness of centering and adjustmarkings accordingly.
c) Mark center line. Scribe a line onthe cover of the belt from the belt endto the clamp. This line must bedurable enough to remain evident
25
Fig. R - Details of fill-in for Flexseal belts without breaker.
Fig. S - Details of fill-in for Flexseal belts with breaker.
throughout the entire splicing opera-tion.
B. Laying out splice area
(Refer to Tables 11 and 12). Careshould be taken to get the splice asclose to level as possible.
1. Establish a perpendicular lineacross belt near belt end. To do this,select a point on the center line aboutsix feet from this point to a point onone edge about 12 inches from thebelt end. Repeat to find a corre-sponding point on the other edge,measuring the same distance from thepoint on the center line. A line drawnbetween these two points will be per-pendicular to the belt edges.
2. Locate and Mark Splice ReferenceLines and Step Lines.
a) Determine splice angle. From oneof the edge marks established in 1above, measure back a distance of 0.4times the belt width (example: for 60”belt width, 0.4 x 60” = 24”) alongthe edge, and mark this point. Drawa line from this new point to the endof the perpendicular line on the otheredge. This will establish the spliceangle. This line can also serve as lineC or H (Table 12) depending onwhich end is being worked on first.
b) Cut belt end along either line C orH. To facilitate cutting, it is suggestedthat the top cover be removed in a 2”wide strip centered along line C or H.The preferred method of cuttingcables along the belt has been withcircular “carborundum” cuttingblades.
c) Referring to Table 12, locate thesplice step lines (not the individualcable cut locations) by measuring backfrom the points established in “a”above. Draw step lines on belt coverwhich is up. Mark edges at step linesfor bottom side. The bottom step willbe drawn in later.
C. Stripping and preparation of belt ends
1. Bevel cut through top cover at thecover fill-in line (Lines A or K inTable 12). Cut through top cover atline C or H. Strip off the coverbetween cuts (3” wide x width of beltat bias angle).
2. Cut through impact ply at fabricstep line (Line C or H, Table 12).
26
A. ClampsB. 2” x 4” wood sideboards, both sides of table.C. Rhombic shaped, 22 deg. bias, bottom platens of vulcanizer. These platen surfaces must be flush
with surfaces of table end sections.D. Determined by length of vulcanizer sections to be used to cure the steel cable belt splice in one heat.E. Each end table section should be 8’ to 10’ long x belt width + 12”.End table sections must be very sturdy and must be fastened down securely to avoid shifting. Applysideboards as indicated in splicing instructions. A 3 ft. wide walkaway should be provided on each sideof table.Work table should be 30” above walkway and 18 to 20” above conveyor decking.
Measure across belt in several areas and mark center in each case, as indicated by x’s above. Drawline through x’s to establish centerline. Select point “C” on centerline approximately 6’ from end of belt.Measure, and mark, a point on each edge, equidistant from “C”. Draw a line between these points,shown as “R” above. Use this line for location of splice reference lines and step lines.
TABLE 10 - WORK TABLE FOR STEEL CABLE BELT SPLICING
TABLE 11
TABLE 12
Note: Rhombic shape of platen dictates splice to be used as shown in Table 10 and oppositedirection in Table 12
3. Strip off top cover from remainderof splice area. The impact ply shouldnot be removed during this stepbecause, in doing so, it can take muchof the rubber between cables with it.
4. Fold back the belt to expose thebottom side of the splice area. Drawthe step lines for the bottom steps.The marks for these steps were madeon the edges of the belt in Step B-2-C.
5. Cut bottom steps. Bevel cutthrough bottom cover at bottom coverfill-in (line B or J). Cut through bot-tom cover at bottom impact ply stepline (line C or H). Strip out bottomcover between these cuts (1-1/2” widex width of belt at bias angle).
6. Cut through bottom impact ply atstep line (Line C or H).
7. If bottom cover is greater than1/8”, remove it from the remainder ofsplice area. Otherwise, proceeddirectly to Step C-8.
8. Suspend splice area. Attach visegrips or some similar clampingdevices on end of belt, and attachthese to pulling devices such as comealongs, Lug Alls, or similar. Applytension with pulling devices and sus-pend belt end.
9. Cut out material between cables.Cut on each side of each cable verti-cally through entire remaining beltstructure (i.e., cable gum, top andbottom impact plies, and bottomcover, if 1/8” or less. The length ofthese cuts to extend from the end ofeach cable to the step lines at either Cor H. Cut off the material strips atthe approximate step line.
10. Cut off material on top of cables.Trim the cable rubber and impact plyaway from the top of each cable. Thecut is made in a horizontal plane,using the cable itself as a guide whilecutting. The length of each cut willextend from the end of the cable tothe step line, either C or H. Removethis material by cutting at the appro-priate step line.
11. Cut off material on bottom ofcables. Remove the visegrips, and lay the belt endback. Trim off the bottomcable rubber, impact ply,and cover if left intact, in a
fashion similar to that outlined in StepC-10.NOTE: The intent of Steps 9, 10, and 11 is to remove
as much material (impact ply and rubber) as possiblefrom each cable without exposing the “bare” metalsurface of the cable. This is often referred to as “cub-ing” operation because of the square profile of rubberwhich remains on the cable.
This method of cable trimming shouldexpose a minimum bare metal. Asmall amount of such exposure can betolerated. The strength of this vulcan-ized steel cable splice depends on thelevel of cable adhesion to the originalrubber surrounding it. The new cablegum bonds on the original cubed cablegum surrounding each cable. In otherwords, the splice strength depends onthe shear adhesion resulting from arubber/rubber bond, rather than a rub-ber/metal bond.
In cases where,
(1) Excessive brass metal is exposed;
(2) Corrosion or other causes havedeteriorated the bond between theoriginal rubber and the brass cable;
(3) The cable is exposed and is zinccable;
Refer to special procedures inAppendix A on page 36.
12. Place belt end back onto worktable.
13. Clamp belt to table, and apply sideboards. Line up center line of belt sothat it is approximately in center oftable, and parallel to edges of table.Clamp, with full width clamp to endof table. Nail on side boards snugagainst belt edges. See Table 10.
14. Mark the four cutting, or steplines, on each cable. These cable-cutlines are referred to as lines 1, 2, 3,and 4 in Table 12. Locate these linesby measuring from the reference lineson belt which now is clamped intoposition.
15. Apply a strip of masking tape orsimilar material along top step line C
or H, full width along bias.
16. Mark each cable as to its cuttinglocation. On the masking tape, desig-nate the cable as 1, 3, 2, 4 and 1, 3,2, 4 etc. on across to indicate alongwhich cable step line they should becut.
17. Cut each cable at the correspond-ing step location.
18. Clean and buff the bevels of thetop and bottom cover fill-in areas.Buff top cover bevels (Line A or K).Pull belt end back. Buff bottom coverbevels (Line B or J). Buff so that con-tact surface is rough.
Instructions for use of cementsand solventsThe splice buildup will involve the useof cements and solvents. The follow-ing instructions are very important.Read carefully. Except in specialcases, instructions given here will notbe repeated in the step by step processof buildup. Also, refer to Table 13for a pictorial description of thearrangement of the various materialsin the splice.
Cements - In all steps in building upthe splice, cement is applied to all sur-faces to be joined. The cement to beused is Grade C which is a 50:50 mixof #636 and #637 cements. Mix equalparts of each for belts. For neoprenebelt, use one part neoprene Grade Scement. Cement is to be applied asfollows:
a) All unvulcanized surfaces (impactply, cover stock, cable gum) - Applyone coat of cement.
b) All vulcanized surfaces (trimmedcables, ends of cured covers, steps incured belting) - Apply two coats ofcement.
Full coverage with a thin layer of27
CUBED CABLE
TABLE 13 - Arrangement of materials in splice.
cement is more reliable than a thicklayer of cement. Always allow thefirst coat of cement to dry thoroughlybefore applying the second coat.
Solvents - R-587-T is the recommend-ed solvent to clean off all uncementedsurfaces. It should be used if any dirtappears on the surface of any splicingmaterial, cured or uncured. However,if cement has been applied to the sur-face, the solvent should not be used asit will soften and may remove thecement. The only exception to this isthe case of extreme dirt deposit on thecement coat. In most cases, if acemented surface has a slight dirtdeposit, apply another coat of cement.
A bloom or film may appear on thesurface of unvulcanized cover stock.This is a natural condition created bythe age resistors in the rubber. If itappears, the surface should be cleanedwith R-587-T solvent before applyingcement. The solvent can be appliedwith either a rag or a felt pad.
19. Clean cables using solvent.
20. Cement cables. After solvent isdried, apply first coat of cement toeach cable and each cover fill-in area.This cement can either be brushed onor also applied with a fabric or spongepad (as preferred).
21. This completes preparation of thefirst end of the belt. When the cementis dry and non-tacky, wrap the cablesin polyethylene film and lay back offcenter section of table. Do notremove belt from table. Leave fullwidth of clamp and side boards intact.
22. Lay second end of belt on table,covering center and end section oftable.
23. Establish center line as on firstend. Line up center lines on the twoends to be spliced. Use a string orequivalent. Center lines should beperfectly aligned. During this sameoperation, ends of belt must be inproper relative position or distanceapart. Refer to Table 12 for requireddimensions. Actually, it is not manda-tory that the exact overall length bemaintained. The required lengthaccording to the sketch can be variedseveral inches by varying the distancebetween the step lines (C and H) andthe first cable step lines (1 and 4).This distance, specified as 7”, couldbe be as little as 5”, or could be asmuch as the cable lengths will allow.
However, extra length here increasessplice length and could in some casesincrease the number of heats requiredfor curing the splice.
24. When the two ends are aligned,nail the side boards against the edgesof the second end and apply full widthclamp at this end of the table.
25. Lay out the splice area same as forfirst end, making sure splice anglematches angle on first end. Care mustbe taken so that all dimensions scribedon this second end match the corre-sponding dimensions already patternedon the first end.
26. Strip down splice area in samemanner as first end. Do not cut cablesto length at this time on second end.However, the cables are “cubed,”cleaned, and cemented as described inprevious steps within this section.
This completes stripping and prepara-tion of the belt ends.
D. Assembly of bottomcover pad1. Remove both ends of belt fromwork table without disturbing thealignment or the dimensional relation-ships of either end with respect to thefixed reference marks.
2. Prepare full width bottom cover.This will cover an area between coverfill-in lines B and J (Table 12). Thecuts along lines B and J will be alongthe splice bias angle and should have abevel cut similar to the matching coverfill-in lines. Place bottom cover ontowork table (film side down). Applyone coat of cement to top side. Cuttwo sufficient width strips of HollandCloth on the bias to amply cover areasBC and HJ respectively. This will aidsubsequent operations in the assemblyat the bottom cover pad. (NOTE: Donot remove these inserts until the exe-cution of Step E-3).
3. Prepare full width bottom impactply. The length should be approxi-mately 2” longer than the distancebetween Step lines C and H. The cutsalong lines B and J will be on theappropriate bias angle. Apply onecoat of cement to bottom side of fabric(film remaining on top side).Laminate cemented side of fabric tocemented side of cover stock posi-tioned on work table. Stitch or rollboth members of “pad” together.Trim impact ply along fabric step linesC and H. Remove film protecting top
side of fabric. Apply one coat ofcement to entire top surface of pad.
4. Prepare full width bottom cablegum layer. The bias length cutsshould be identical in dimensions tothose of the bottom impact ply as out-lined in Step D-3. Apply one coat ofcement to bottom surface of cablegum, (film remaining on top side).Laminate cemented side of cable gumto cemented side of pad. Stitch or rollall members of pad together.
Trim cable gum along fabric step linesC and H. Do not remove film on topside of pad (covering cable gum sur-face) at this time.
5. The assembly of the bottom coverpad is now complete. Remove padfrom the splice area.
E. Joining of belt ends1. Prepare work area (bottom vulcan-izer platen) with special release agent(mica dust, Mylar, Teflon treated glassfabric, etc.). If mica dust is used,care must be exercised to confine thedust to the vulcanizer surface only.
2. Remove film from the bottom coverpad (film adjacent to bottom cover sur-face).
3. Place pad onto vulcanizer (with bot-tom cover side adjacent to vulcanizersurface). Position and match lines Band C of the pad to the correspondingreference lines on one belt end.Remove Holland Cloth covering thearea, between lines B and C.Carefully join these surfaces together.In a similar fashion, carefully matchand join the area described by lines Hand J on the other belt end.
4. Match cables from second belt end.Two men must work together in thisoperation, and sometimes two pairs oftwo men are used, one pair on eachside of belt. This operation must bestarted at the center cable (if there isan odd number of cables in the belt) orthe two center cables (if there is aneven number of cables in the belt).Work must proceed from the center tothe edge on both sides. If two menonly are working, they start in centerand then alternately match a pair ofcables on one side of belt, then a pairon the other side. If two pairs of menare working, each pair will work onone side only. The procedure is asfollows:
a) Locate center cable(s), in each end.
28
b) Mark cable from second end of beltjust short on matching cable alreadycut from first end of belt.
c) Cut cable as marked.
d) Cable gum film still remains on topof the bottom cover pad. Remove thisfilm as the cables are cut.
e) Apply one coat of cement toexposed cable gum surface. Applysecond coat of cement to cover fill-inareas and all cables. (First coat hasalready been applied. See Steps C-20and C-26). The tack of these cement-ed surfaces (cable and cable gum) willmaintain the desired alignment of thecables until vulcanizer pressure isapplied during the curing process.
f) Match, cut, and lay all remainingcables of second belt end. Proceedwith the cables adjacent to the centercable(s) and alternately advance outtoward both edge cables.
F. Completion of the splicebuildup1. Apply additional cable gum stripseach side beyond edge cables to coverarea out to edges of impact ply, cablegum, and bottom cover. Cementexposed surface of each cable guminsert. Apply to the appropriate loca-tions at the belt edge, bonding to thecemented surface at the bottom cablegum layer. Stitch or roll surfaces.Remove film on top of cable guminserts. Apply one coat of cement.
2. Prepare top cable gum layer. Cutcable gum to cover splice betweenSteps (lines C and H). Cementexposed surface of cable gum andapply on top of cables. Trim at Steplines C and H. Stitch or roll surfacestogether. Remove film on top cablegum layer. Cement exposed surface.
3. Prepare top impact ply. Cut impactply to also cover splice between Steps(lines C and H). Cement exposed sur-face of impact ply and apply on top ofcable gum. Carefully trim step linesC and H. Stitch or roll surfacestogether. Remove film top of impactply. Cement exposed surface.
4. Trim edges of splice, making widthabout 1/4” less than width of originalbelt. Thus, cut each edge approxi-mately 1/8” in from edges of curedbelt outside of splice area. Apply onecoat of cement on edges.
5. Prepare top cover (or top cover lay-ers). Cut top cover stock to cover
area slightly larger than that betweencover fill-in lines A and K. Bevel onebias cut on either line A or K.Cement exposed surface of coverstock. Apply cover on top of impactply filling precut bevel at one end, andcarefully fitting and skiving the otherend. Stitch or roll entire composite,including both cover fill-in junctions.Remove film on top side of coverstock. Trim edges of cover stock totrim width determined in Step F-5.
6. Edge buildup. Build up both edgeswith cover stock material to thicknessdesired (1/4” minimum). Skive excessflush with top surface of belt. Thesplice should be about 1/4” wider thanthe adjoining cured belt.
7. Prick the top cover with a sharpawl. Depth of pricking should extenddown into cable structure.
8. Treat top cover and edges with spe-cial release agent. The followingguides should be considered:
If mica dust is used,
a) lay a 3” wide strip of Holland Cloth(or equal) over both top cover fill-inseams.
b) dust top cover and edges with micadust.
If Holland Cloth (or equal) is usedinstead of mica dust, lay HollandCloth completely over top cover sur-face of splice.
This completes the buildup of thesplice.
G. Curing (Single heat
vulcanizer)1. Vulcanizer platens must extendbeyond the splice area not less than 4”on each end.
2. Position edge irons on bottom plat-en. Edge irons must be at least aslong as the vulcanizer platens. Theyshould also be set up to the samewidth as cured belt width. The edgeirons to be used should be 1/16” to3/32” thinner than the cured belt thick-ness. They should be at least 3” wide,and at least 6” longer than the vulcan-izer length including cold ends. Inuse, the edge irons must be solidlybacked up as the pressure on them willbe much greater than that encounteredwith textile belts.NOTE: If Holland Cloth (or equal) were used as thevulcanizer release agent rather than mica dust, place astrip of Holland Cloth over the edge iron surface whichwill contact the belt edge. Then apply edge irons flushagainst both edges.
3. Assemble top platens and other vul-canizer parts on top. Attach electricalconnections and pressure system.Start heating.NOTE: It is highly advisable to have thermometersinserted into the edge of platens (e.g. Weston Dial) as acheck on platen temperatures. If a question exists inregard to platen temperatures, a thermocouple checkshould be made. Using a scrap piece of belt betweenplatens and thermocouples on top and bottom belt sur-face is a reliable method of checking platen surfacetemperatures before proceeding with the splice cure.
4. Apply pressure as follows:
a) As heating begins, apply 50 psi.Then release pressure. Such “coldpressing” is recommended operatingprocedure.
b) Apply 50 psi until temperaturereaches 150 deg F.
29
TABLE 14 CURE TIMES AND TEMPERATURES FOR STEEL CABLE CONVEYOR BELT
BELT GRADE
285 deg F CURE 300 deg F CURE 300 deg F CURESet platens at 285 deg F
Count time from 280 deg FSet platens at 300 deg F
Count time from 295 deg FSet platens at 300 deg F
Count time from 295 deg F
WaterCool Down
AirCool Down
WaterCool Down
AirCool Down
WaterCool Down
AirCool Down
1/2” to 5/8”
5/8” to 3/4”
3/4” to 7/8”
7/8” to 1”
1” to 1-1/8”
1-1/8” to 1-1/4”
1-1/4” to 1-3/8”
1-3/8” to 1-1/2”
28
30
35
40
45
50
55
60
25
28
30
35
40
45
50
55
25
28
30
35
40
45
50
55
25
25
28
30
35
40
45
50
35
38
40
45
50
53
57
60
30
33
35
40
45
48
52
55
RMA GRADE I II NEOPRENECABLE BELT
Blair Rubber recommends 285 deg F for I and II belt, but recognizes some presses may be set at 300 deg F. At 300deg F, greater care must be exercised to assure uniform platen temperatures and not to overcure the splice area.Overcuring of Longlife and Super Longlife cable gum is detrimental to the splice rubber strength. Platen uniformityshould be within 5 deg F of the selected temperature.The platen temperature should be set at the selected temperature and cure time counted from the time the platensreach 5 deg F below this temperature.
c) When temperature reaches 150deg F, increase pressure to 100 psi.
d) When temperature reaches 200deg F, increase pressure to 175 psi.
5. Carry the cure the required numberof minutes using Table 12. BlairRubber recommends 285 deg F for Iand II belt, but recognizes some press-es may be set at 300 deg F, greatercare must be exercised to assure uni-form platen temperatures and not toovercure the splice area. Overcuringof I and II cable gum is detrimental tothe splice rubber strength. Platen uni-formity should be within 5 deg. F ofthe selected temperature. Start timingcure when temperature has reached 5deg F below the temperature selectedfrom Table 14. This chart shows thecuring times and temperatures, basedon the grade of the belt and the beltthickness. Use the cured belt thick-ness when referring to this table.
6. When cure is completed, a water“cool-down” is recommended if avail-able. If “air” cool -down is used, usethe appropriate time from Table 12.Cool-down should be to 200 deg F orlower before releasing the pressure.
7. Remove vulcanizer and any releaseagents that may remain attached to belt(e.g. Holland Cloth).
8. Inspect the splice. Trim edgesand/or make any other appearancemodifications as may be necessary. Ifa rubber hardness instrument is avail-able (e.g. Shore A Durometer), checkthe rubber for uniformity of hardness.The splice is completed. The belt isoperational at this point, although it isrecommended that splice be allowed tosit at ambient temperature for two orthree hours before subjecting it tooperating tension.
Overlap spliceFor many applications it is possible tomake a shorter splice than the butt-step splice with steel cable belting.The overlap splice may be used wherethe cable spacing is wide enough toallow enough rubber between thelapped cables to provide the requiredhigh splice strength.
The overlap splice, where applicable,will produce an equally reliable spliceto the butt-step splice.
Overlap splices are not recommendedfor belts rated higher than No. 2800.
Much of the procedure for the overlap
splice is similar to the procedure forthis butt-step splice. Therefore theprocedure for the overlap splice isabbreviated by reference to the butt-step splice procedure where suchduplication exists.
Both procedures are almost identicalexcept for splice buildup. Two addi-tional charts are required. These aretables 15 and 16.
A. Belt replacement on table andestablishment of center line. (Table10 and 11).
The procedure is identical to the butt-
step splice (pages 30 - 34).
B. Laying out splice area (Table 11and 15 or 16).
The procedure is identical to the butt-step splice (page 31) except Table 15or Table 16 will be used instead ofTable 12.
C. Stripping of belt ends.
Follow the same procedure as for thebutt-step splice steps 1 though 13.Refer to Table 15 or Table 16 insteadof Table 12.
Omit steps 14 through 18.
30
TABLE 15 - OVERLAP SPLICE
TABLE 16 - COMBINATION OVERLAP/BUTT SPLICE
NOTE: Rhombic shape of platens dictates splice angle.
Build up Splice - The belt ends mustbe clamped in the proper relative posi-tion, and not moved, during splicebuild-up. Do not tension the splice.Follow same “Instructions for use ofCements and Solvents” detailed onpages 32 - 33 for butt-step splice.
1. Clean entire splice area, includingcables, with solvent.
2. With belt ends in position, deter-mine exact dimensions required forbottom cover, bottom breaker (ifincluded), bottom fabric ply, and bot-tom layer of cable gum.
3. Cut bottom cover, bottom breakerif included, bottom fabric ply, and bot-tom layer of cable gum to size asdetermined in step 2 above, with endsof cover leveled.
4. Assemble bottom cover, bottombreaker if included, bottom fabric, andbottom layer of cable gum.
5. Lay belt ends back.
6. Clean bottom cover fill-in areas onbelt ends with solvent, and cement,two coats.
7. Lay bottom cover assembly onwork table in proper location. Place a3” strip of Holland under the ends ofthe bottom cover, with half of Hollandextended beyond ends.
8. Fit one belt end to bottom assem-bly. Start at one side and workacross, carefully fitting both the fabricstep and the cover.
9. Fit other belt end to bottom assem-bly, again carefully fitting the fabricand cover steps.
10. Cement cables, two (2) coats.
11. Lay cables. Refer to Table No.15 or 16, whichever is appropriate forpattern of cable placement. Detailsare as follows:
a) Number the cables. Apply a stripof masking tape or similar materialalong the fabric step line, both ends.Number the cables on the maskingtape. This will help assure that corre-sponding cables from the two belt endsare located in the proper relationshipin the splice.
b) Cement cable gum surface on bot-tom assembly two coats.
c) Lay center cable. In both TablesNo. 15 and 16, center cables arebutted. Always start with the centercable. If the belt has an even numberof cables start with one of the two cen-ter cables. Butt the center cable at theproper line as indicated in Tables 15or 16, leaving 1/4” to 1/2” gapbetween the cable ends. Fill the 1/4”to 1/2” gap with a piece of cable gumstrip.
d) Continue laying cables on each sideof the center cable. When applyingthe Table 15 layout, this will involveoverlapping all the cables. Whenapplying the Table 16 layout, this willinvolve alternately overlapped andbutted cables. If one man only isdoing the work, he should alternatesides, first laying a cable on one sideof the center cable, then laying a cableon the other side of the center cable.
e) Check cable alignment regularly, atleast once each six cables. Checkalignment with a straightedge. If cablebuildup is becoming wide, butt anadditional cable. Alignment shouldnever be off more than the width ofone cable. Additional butted cablesare permissible in the Table 15 layoutno more frequently than every 12thcable. The cables should be buttedapproximately midway between linesE and F. In Table 15, additionalbutted cables are permissible onceevery ten cables. The cables in thiscase should be butted not at lines F, Gor H, but rather alternately at lines D,E, J or K.
f) Fill in voids at ends of cables.After all the cables have been laid,there will be voids between line Cand E (Tables 15 and 16) and betweenF and H in Table 15 or J and L inTable 15. These are the areasbetween the ends of the overlappedcables and the fabric step lines. Fillthese voids with appropriate quantitiesof cable gum strips.
12. Complete remainder of splicebuildup using same procedure as spec-ified for the standard type splice.Refer to Page 34, steps F1 through F8(Table 15 or 16).
Curing - Short splices are cured inexactly the same manner as are stan-dard splices with the one exception of
tensioning. Refer to section G, butdisregard the instructions for tension-ing the splices during cure.
Steel Cable BeltAppendix ASpecial procedure for preparing cablesurface for I, II and FR-SBR cablebelts (i.e., general purpose belts, butnot neoprene or other special polymerbelts).
When splicing or repairing used brasssteel cables with minor exposed cablebut no rust or corrosion, apply C-636and C-637 cement to the original rub-ber that is still bonded to the cables.
When splicing or repairing used brasssteel cables with major bare metal orwhere some corrosion or other causehave exhibited loss of adhesion of therubber, use the procedure below.
Procedure - barecablesA. Buff all rust and rubber fromcables.
B. Wipe and clean buffed cables withisopropyl alcohol or ethyl alcoholwhich can be obtained from localsources.
C. Apply heat (mild heat gun) to dry.
D. Degrease by wiping thoroughlywith solvent R587T.
E. Allow to dry. Apply heat (mildheat gun) under moist conditions.
F. Apply one coat Thixon OSN-2cement to bare cables.
G. Allow to dry. Apply heat (mildheat gun).
H. Keep clean.
I. Proceed with standard splicing pro-cedure, which includes a lightlyapplied coat of Grade C cement overthe dry OSN-2 cement.
Note: The key to a successful resplice
31
is to not have any C-636 and C-637applied to bare cables. The presenceof OSN-2 on rubber surfaces is okay.
SPLICING STEELCABLE BELTSWITH UNEQUALNUMBER OF CABLESIt is possible to reliably splice togethersteel cable belts with unequal numbersof cables (different cable spacing).
It is also possible to reliably splicesteel cable belts with modest differ-ences in cable diameters using thesheeted cable gum method of splicing.
Where an unequal number of cablesexist, the simple overlap splice shownin Table 15 page 35, should be used.
The only limitation is that we musthave approximately a 3/32 inch gapbetween cables in the assembledsplice.
The space between cables in a simpleoverlap splice after assembly can becalculated as follows:
spacebetween=
(BW - 1.5) - (N1d1 + N2d2)
cables N1 + N2 -1
where, BW = Belt width (3/4” edgecap is assumed)
N1 = No. of cables in belt 1d1 = Cable diameter of belt 1N2 = No. of cables in belt 2d2 = Cable diameter of belt 2
For example:
It is desired to splice belt 1 with 80cables, 1/4 inch in diameter into belt 2with 91 cables, 7/32 inch in diameter.The belts are 60 inches wide.
The spacing between cables in a simpleoverlap splice after assembly will be:
spacebetween=
(BW - 1.5) - (N1d1 + N2d2)
cables N1 + N2 - 1
=(60 - 1.5) - (80 x .25 + 91 x .219)80 + 91 - 1
=58.5 - 39.9 170
=.109 inches
This is greater than 3/32 inch, so asimple overlap splice can be madewith the following exception.
Since there are 11 more cables in belt
2, two cables from belt 2 must beintroduced together in the lappingeleven times.
Determine the point at which doublingup of the cables from belt 2 will occuras follows:
interval = N1
N2 - N
where, N1 = No. of cables in belt with least no.
N2 = No. of cables in belt with greatest no.
therefore,
interval = 80 = 7.27 (use 7)91 - 80
After every seventh cable in the 80cable belt, two cables will be insertedfrom the 91 cable belt.
The entire splicing procedure will bethe same as for a conventional overlapsplice including butting an occasionalpair of cables if the center of the splicebegins to become wider than the endsduring assembly.
SPLICING LIGHT-WEIGHT BELTSThe splicing procedure is the same asshown for fabric belts without break-ers with the following exceptions:
1. Laying out: Use a 4” long step.For belts with covers remove 1/2” ofcover from each end plus allowancefor trim to provide for a one-inch fill-in strip.
2. Cover fill-in: Undercut both edgesof cover at fill-in. No lightweightbreaker fabric is used over butt jointseams in the outer fabric plies.
3. Curing splice in vulcanizer: Use
polished steel or aluminum plate invulcanizer to obtain surface in splicecomparable to top cover of belt.
Repairingconveyorand elevatorbeltsMinor repairsMinor vulcanized repairs to covers. Aminor repair is one that involves onlythe belt cover and breaker, and usuallyis of small area.
Materials needed for minorvulcanized repairs: Cement. Coverstock to match that in belt. Uncuredbreaker fabric or transcord breaker ifthis is to be replaced. Solvent.Holland cloth. Repair materials aresame as for splicing.
Tools for cover repairs include mostof those employed in splicing (page14).
1 - If repair area is not large, make itany convenient shape except squarewhen cleaning out damaged material.If it is of considerable size, make itapproximately diamond-shaped. Trimtwo edges of repair cavity parallel tobelt edges. Position leading and trail-ing edges at a 20 deg to 22 deg bias.Layout of this diamond is same as forthat shown in Fig. Z.
2 - Cut out snagged or loose portion ofcover. Hold knife so cut edges make60 deg angle with belt surface. Safestway is to cut almost through cover -within 1/64” of fabric. When dam-aged portion of cover is pulled loose,uncut 1/64” will tear through to fab-
32
ric.
3 - Clean loose particles from repairarea. Use prodder to remove adheringpatches of rubber. With coarse emerycloth, buff thoroughly the cut edges ofrubber and clean the fabric. If carcassis wet, use hot-air blower or heat fromvulcanizer to drive out moisture; heatlamps can be used, but with caution toavoid overheating. Buff dried fabriclightly with emery cloth to raise nap.
4 - Apply two coats of cement toexposed fabric and beveled edges ofrubber allowing first to dry thorough-ly, second until tacky.
5 - Fill cavity with uncured coverstock, making it level with surround-ing rubber. If one thickness of coverstock is insufficient, apply successivelayers; increase tackiness of layersalready placed by applying cement orsolvent. Roll each layer into goodcontact. Deflate blisters.
6 - Place Holland cloth over repairarea, letting it extend 1/2” each way.This increases vulcanizer pressure andproduces a smooth job.
7 - Vulcanize repair without delay.Have vulcanizer heated to curing tem-perature beforehand. Length of cureis same as for splicing, as shown inTable 7.
8 - Trim off loose overflow by buffingwith coarse emery cloth.
Major repairsIn a major belt repair, material isreplaced in belt carcass as well as incover. The variety of such repairs isso great that definite instructions tocover all cases cannot be given, thefollowing suggestions are to be regard-ed as general - to be supplemented,when necessary, by good judgement.
Materials needed for major beltrepair: Fabric and cord ply materials- Fabric is sold in strips with warpthreads running lengthwise. Whenplacing fabric in belt, use weight tomatch original ply, grade to matchrubber. Put skim coat toward belt.Place fabric so warp threads, whichare tension members, parallel beltedges. Transcord breaker should bepositioned with its tension members(cords) crosswise belt. Tie gum - useproper grade, thickness. Cement - usegrade to match rubber.
Tools: Same as for splicing. Spliceor repair? First decide on proper pro-cedure: Can belt be repaired success-
fully? Or should affected portion becut out and a new splice made, or anew section spliced in?
These factors help determine whetheror not a major repair is advisable:Amount of belt width affected by cut.Operating tensions. Starting character-istics of loaded belt. Frequency ofstarts or stops. Such factors are thebasis for Table 22.
Using table: If all three conditions inTable 22 - extent of cut, operating ten-sion, starting conditions - show“repair,” a repair should prove satis-factory. If any one condition shows“splice,” do not attempt repair;instead, remove affected belt sectionand resplice. A “repair or splice”condition requires the use of carefuljudgement in selecting proper treat-ment.
Edge repairs: When a repair at ornear belt edge is quite long, pressureapplied to the new stock during vul-canization causes that side of belt toelongate. Also, replacement fabricwill not have same stretch characteris-tics as original. Consequently,repaired belt may have one edgelonger than other, and thus tend to runto one side.
Making repair from one side only:Cut and remove damaged cover andcarcass plies. See photo 55. When
damage does not extend all the waythrough belt, this can be done fromone side only. Use same tools and
33
TABLE 22 - FACTORS DETERMINING WHETHER BELT SHOULD BECUT AND SPLICE OR REPAIRED.
(1) - Across-the-line starting (applying full-load starting characteristics of motor to belt may range up to,sometimes beyond, 200 percent of motor horsepower.(2) Controlled starting is where torque applied does not exceed 150 percent of operating torque.
ConditionsExtent of cut or repair
Percent of belt width affected
510
15 and over
304552
Operating tension - Percent of belt manufacturer’s ratingup to 45%
45% to 65%65% to 100%
Starting conditions
Starting is
Infrequent -
three times
per day or
shift
Frequent -
more than four
times per day
or shift
X
X
X
X
X
XX
X
X
X
X
X
X
X
XX
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Belt is Kind of starting
Loaded EmptyAcross-
the-line (1)Controlled
(2)
Percent of strength loss
What to do
RepairRepair or
Splice Splice
Fig. Z - Major belt repair from one side (beltsurface).
methods as when stepping-down a beltfor splicing.
Figure Z shows belt preparation forrepair from one side only. The “dia-mond-shaped” cavity is positioned asdescribed for minor vulcanized repairswith leading and trailing edges on abias angle of about 20 deg. Stepswhose longer dimensions paralleldirection of belt travel (Y-Y, Fig.Z)are shorter than those on bias angle(X-X, Fig. Z). Steps marked “A” insame figure are called tension stepsbecause they are under tension whenbelt operates. They are made longerthan the transverse steps.
Making repairs from both sides ofbelt: Figure BB shows a major repairin which carcass is stepped from both
belt surfaces. Less area is needed forstepping than when repair is from onlyone side.
Cut tension steps on opposite biasangles. Their lengths depend on beltoperating tension, but usually are 3” to5”. Transverse steps “B” range from1” to 3”, the greater length beingdesirable when loading conditions aresevere. Stagger transverse steps withrespect to similar steps on oppositeside of belt, so no two are exactlyopposite each other.
Repairing slit or break running
lengthwise: Make repair from bothsides of belt. Stagger the transversesteps. Cut tension steps on an alter-nate bias, as shown in Fig. CC.
Edge repair: When damage is at beltedge, use the same diamond principleas for the previous methods. Makesteps from both belt surfaces, stagger-ing them for greater strength. Formthe steps by cutting along lines whichare about 45 deg. to belt edge (SeeFig. DD). To obtain good adhesion ofnew edge cover stock, extend breakerfabric around repaired carcass edge.
In stepping-down for a repair involv-ing part of carcass, you will removesuccessively smaller pieces of fabric.When laying out the repair, determinesize of last ply that is to be removed,so all damage will be included. Oryou can make a small cavity at first,then enlarge it as required.
Remove all skim-coat rubber fromsteps. Buff fabric lightly with emerycloth to raise nap.
Rebuilding repair area:1 - After stepping-down and cleaninghave been completed, dry exposed fab-ric with heat lamp or hot-air blower ifbreak had admitted water. Brush twocement coats on steps and rubberedges of repair cavity, allowing first todry thoroughly, second until tacky.Apply one light coat of cement toskim-coat side of piece of fabric that isto be placed first, and let dry untiltacky. This piece should be somewhatlarger than area it is to occupy.
2 - Position repair fabric in repair cav-ity. Roll it into good contact. Withprodder or stitcher, force new fabricinto position along edges of originalfabric.
3 - With bevel-point knife, trim offexcess material. Edges of new fabric
should make neat butt joint with edgesof original ply. See Photo 56.
4 - Brush light coat of cement oversurface of newly-placed fabric andover skim-coated side of next repairpiece. Let dry until tacky.
5 - Apply second repair ply as before.Repeat until cavity has been filled tobreaker ply.
6 - Install new breaker fabric ortranscord breaker in same way as
other fabric plies. Cords must runcrosswise belt at right-angles to edges.Trim off excess with bevel-point knife.
7 - Brush coat of cement on breakerand let dry until tacky. Remove poly-ethylene film from piece of coverstock, and brush light coat of cementon rubber. Apply cemented surface ofcover stock to repair area. Roll firm-ly. Force edges into place with stitch-ers in photo 58.
34
Fig. BB - Section through minor repaircavity showing rubber beveled to 60 deg.
Fig. CC - Repair of long slit or break run-ning lengthwise belt.
Fig. DD - Repair at belt edge.
Fig. AA - Major belt repair from both sides(belt surfaces).
8 - Trim off excess rubber with bevel-point knife. See photo 59. Punctureair pockets.
9 - If another thickness of cover isrequired, cement one already placed,and repeat operation. Build up cover1/64” to 1/32” higher than surround-ing area. Where repair depth extendsseveral plies and from one side only,build-up should be 1/32”
10 - Cover the area of repair withHolland cloth or linerette paper 1/2”larger all around than filled area.Cure in vulcanizer. Remove cloth or
paper after curing. With abrasivepaper, trim off any rubber overflownot adhering to surrounding cover.
Vulcanizing repair: Small, portablevulcanizers are available for curingrepairs, or a splicing vulcanizer can beused. Use a two-platen vulcanizer forany repair whose over-all depth (thick-ness) is more than 5/16”. As in splic-ing, undercuring in belt repairingresults when vulcanizer develops acold spot. To complete the cure whenthis occurs, shift vulcanizer and curearea that was under cold spot. Mostpresent-day rubber compounds willstand three to five curing heats beforetheir strength and other properties areaffected.
For further information about vulcan-izing equipment and operating, seepage 15.
35
36
PRODUCT NO.GRADE GAUGE WIDTH LENGTH
HI-THI-THI-THI-T
HI-THI-THI-THI-THI-T
SSSS
SSSSS
HH
HH
BB
BB
BNI
WNIWNI
.010”
.020”
.030”
.045”
.010”
.020”
.030”
.045”
.010”
.020”
.030”
.045”
.060”
.010”
.020”
.030”
.045”
.060”
.020”
.030”
.020”
.030”
.020”
.030”
.020”
.030”
.010”
.020”
.020”
9”9”9”9”
18”18”18”18”18”
18”18”18”18”18”
9”9”
9”9”
18”18”
18”18”
9”
9”9”
9”9”9”9”
5 YDS.5 YDS.5 YDS.5 YDS.
5 YDS.5 YDS.5 YDS.5 YDS.
5 YDS.5 YDS.
5 YDS.5 YDS.
5 YDS.
5 YDS.5YDS.
10 YDS.10 YDS.
10 YDS.10 YDS.
10 YDS.10 YDS.10 YDS.10 YDS.10 YDS.
10 YDS.10 YDS.10 YDS.10 YDS.10 YDS.
30000300013000230003
3010030101301023010330104
30200302013020230203
3030030301303023030330304
3040130402
3050130502
3060130602
3070130702
30801
3090030901
Standard Tie Gums Available ForTextile Belt Splicing And Repair Materials
37
GRADE GAUGE WIDTH LENGTH PRODUCT NO.
CCCCCCCC
SSSSSSSS
HHH
EPEPEPEP
BBBB
BNIBNIBNIBNI
WNIWNIWNIWNI
1/32”1/32”1/16”1/16”1/8”1/8”3/16”3/16”
1/32”1/32”1/16”1/16”1/8”1/8”3/16”3/16”
1/16”1/8”3/16”
1/32”1/16”1/8”3/16”
1/32”1/16”1/8”3/16”
1/32”1/16”1/8”3/16”
1/32”1/16”1/8”3/16”
18”18”18”18”18”18”18”18”
18”18”18”18”18”18”18”18”
18”18”18”
18”18”18”18”
18”18”18”18”
18”18”18”18”
18”18”18”18”
2 1/2 YDS.10 YDS.
2 1/2 YDS.10 YDS.
2 1/2 YDS.10 YDS.
2 1/2 YDS.10 YDS.
2 1/2 YDS.10 YDS.
2 1/2 YDS.10 YDS.
2 1/2 YDS.10 YDS.
2 1/2 YDS.10 YDS.
2 1/2 YDS.2 1/2 YDS.2 1/2 YDS.
2 1/2 YDS.2 1/2 YDS.2 1/2 YDS.2 1/2 YDS.
2 1/2 YDS.2 1/2 YDS.2 1/2 YDS.2 1/2 YDS.
2 1/2 YDS.2 1/2 YDS.2 1/2 YDS.2 1/2 YDS.
2 1/2 YDS.2 1/2 YDS.2 1/2 YDS.2 1/2 YDS.
3100031001310023100331004310053100631007
3110031101311023110331104311053110631107
312013120231203
31300313013130231303
31350313513135231353
31450314513145231453
31500315013150231503
Standard Cover Stocks Available ForTextile Belt Splicing And Repair Materials
Standard Breaker Fabrics, Holland Cloth & CementsAvailable Textile Belt Splicing And Repair Materials
GRADE TYPE WIDTH LENGTH PRODUCT NO.
C/S MULTIWARP #12 9” 2 1/2 YDS. 32200C/S MULTIWARP #12 9” 10 YDS. 32201C/S MULTIWARP #12 50” 50 YDS. 32202C LIGHT WT.. (011) 19” 2 1/2 YDS. 32213C LIGHT WT.. (011) 19” 10 YDS. 32214
BARE LIGHT WT.. (011) 19” 2 1/2 YDS. 32218BARE LIGHT WT.. (011) 19” 10 YDS. 32217
GRADE WIDTH ROLL LENGTH QUANTITY PRODUCT NO.
C-MULTIWARP 300 54” 2 1/2 YDS. 1 RL. MIN. 33200
DESCRIPTION WIDTH LENGTH SIZE PRODUCT NO.
SOLVENT R-587-T GAL. 32250SOLVENT R-587-T 5 GAL. 32251HOLLAND CLOTH 40” 10 YDS. 32252HOLLAND CLOTH 40” 50 YDS. 32253
GRADE SIZE PRODUCT NO.
B636/637 2 PART QUART 32300B636/637 2 PART GALLON 32301
GRADE S QUART 32308GRADE S GALLON 32309GRADE S 50 GALLON 32310GRADE H QUART 32320GRADE H GALLON 32321GRADE B QUART 32330GRADE B GALLON 32331
BNI QUART 32340BNI GALLON 32341WNI QUART 32350WNI GALLON 32351OTP QUART 32380OTP GALLON 32381
EP (EPDM) QUART 32390EP (EPDM) GALLON 32391
THIXON OSN2 QUART 32370THIXON OSN2 GALLON 32371
900R + ACTIVATOR GALLON 6115
38
Scab Fabric - Grade C/S
Miscellaneous Products
Splicing Cements
Glossary Adhesion: strength of bond betweencured rubber surfaces.
Bag cure: a method of vulcanizationwhere a flexible air-bag is used toimpart positive pressure to splice orrepair being vulcanized.
Beveled: cutting of rubber at anangle.
Bias angle: a cut of belt end or fabricmade diagonally at an angle of lessthan 90 degrees to the longitudinalaxis.
Blow-up: a blister caused by trappedair between rubber and fabric orbetween fabric plies.
Breaker fabric: an open-mesh fabricto improve adhesion between coverand carcass.
Buffing: to grind or rub surface ofrubber to produce a roughened sur-face.
Butt seam: a seam made by placingthe two pieces to be joined edge toedge.
Carcass: the fabric or cable reinforc-ing section of belt.
Center line: accurately measured lineequal distance from each edge of belt.
Cover: outer rubber covering to giveprotection to carcass.
Cure: the process of vulcanization.
Cure time: the time required to pro-duce vulcanization at a given tempera-ture.
Edge irons: strips of wood or metalto provide pressure on edges of beltwhile splice or repair is vulcanized.
Filler thread: the transverse strengthmember in a woven fabric.
Fire resistant: retards the burningaction of fire or flame.
Folded edge: a belt construction withenvelope ply so carcass is closed onedges.
Friction: a rubber compound appliedto and impregnating a fabric.
High tension: relates to fabricsdesigned to operate at tensions over 70pounds per inch per ply.
Holland cloth: a sheeting cloth towhich has been applied a glazed fin-ish; used over uncured rubber duringvulcanization.
Net endless length: the manufacturedlength necessary to provide adequate
service under operating conditions.
PCB: Polyester and cotton blendedfabric.
Platens: heated plates in belt vulcan-izer.
Ply: a layer of rubberized fabric.
Ply adhesion: the force required toseparate two adjoining strength rein-forcing members in a rubber belt.
Reduced ply: High tension fabric toreduce plies necessary.
Skim coat: a layer of rubber laid ona frictioned fabric.
Skive: a cut made on an angle to thesurface to produce a tapered or feath-ered cut.
Tie gum: a thin rubber sheet toreplace original friction and skim coatbetween fabric plies when makingsplices or repairs.
Transverse cord breaker: a breakerfabric with heavy transverse cordmembers.
Vulcanization: the process of apply-ing heat and pressure to rubber com-pounds.
Warp: the yarn that runs lengthwisein a woven fabric.
Weft: the crosswise thread in a fabric- the filling threads.
39