Volume 35 May, 1949 Number 5

£ul ricationA Technical Publication Devoted tothe Selection and Use of Lubricants

THIS ISSUE

Machine Tool Lubricationon the

Production Line

PUBLISHED BY

THE TEXAS COMPANYTEXACO PETROLEUM PRODUCTS

Stop rust and sludge in your hydraulic sys-tems by using Texaco Regal Oils (R & O)as the hydraulic mediums. You’ll assuresmooth, uninterrupted production andlower maintenance costs.

Texaco Regal Oils (R & O) keep hydrau-lic systems clean because they’re turbine-grade oils with special additives to inhibitrust and oxidation - and specially proc-essed to prevent foaming. You can get themin the correct viscosity for your equipment,whatever its type or size.., and they’ll giveyou longer service life than uninhibited oils.

Leading manufacturers of hydraulic

equipment either recommend or approveTexaco Regal Oils (R & O) . . and manyship their units charged with them.

Let a Texaco Lubrication Engineer helpyou get maximum efficiency and economyfrom your hydraulically operated machines.Just call the nearest of the more than 2300Texaco Wholesale Distributing Plants inthe 48 States, or write The Texas Company,135 East 42nd Street, New York 17, N. Y.

LUBRICATIONA TECHNICAL PUBLICATION DEVOTED TO THE SELECTION AND USE OF LUBRICANTS

Published by

The Texas Company, 135 East 42nd Street, New York 17, N. Y.Copyright 1949 by The Texas Company

VoL xxxv May, 1949 No.5

Change of Address: In reporting change of address kindly give both old and new addresses."The contents o[ ’LUBRICATION’ are copyrighted and cannot be reprinted by other publications without written

approval and then only provided the article is quoted exactly and credit given to THE TEXAS COMPANY."

Machine Tool Lubrication on theProduction Line

"’~" F AUTOMOBILES were made today with the ma-

I machine tools of 1910, a single vehicle with1949 refinements, would cost $60,000"-thus

estimated the Automobile Manufacturers Associa-tion recently. What a tribute to the advancementsmade in machine tool designduring the last forty years.

Just as spectacular hasbeen the development of pe-troleum technology duringthis same period. Modern re-fining methods so necessaryto remove undesirable com-ponents of petroleum pr.od-ucts and the use of variousadditives to fortify or am-plify desirable properties aremajor advancements madeduring the last several dec-ades.

As is true with practicallyall industries, advancementsmade in one usually comple-ment or makes possible ad-vancements in another. Themachine tools of today would ~clatter to a sudden stop ifthey were lubricated with many of the productsavailable in 1910. On the other hand, petroleumrefineries could not be operated at economical costswithout modern machine tools to produce the tensof thousands of parts so necessary in their construc-tion and operation.

Machine tools now available are capable of turn-

ASIMPLIFIED Lubrication Plan FotMachine Tools:--the theme of

this article, presents a means for main-taining quality lubrication, yet reduc-ing costs of maintenance and the totalnumber of lubricants used in a givenproduction shop to a minimum.

The formulation of a simplified lu-brication plan must of necessity in-clude a thorough understanding of theoperating characteristics of machinetools and an intimate knowledge oflubricant recommendations issued byindividual machine tool builders. Sucha plan could not be effective withoutthe availability of recently developedlubricants, particularly of the addi-tive type. These lubricants can be usedover a much wider range of operatingconditions than was possible with lu-bricants available not too long ago.

ing out finished products at speeds and with anaccuracy that is astounding. To do this, however,it is necessary that all the parts of a given machinetool function properly. One very important factorcontributing to satisfactory performance is effective

lubrication. Without this, ac-curacy may be lost, oils mayoverheat causing temporarymisalignment of machineparts, or metal to metal con-tact may occur causing rapidwear or complete seizure be-tween moving parts.

Important too is the lengthof time the lubricant "staysput" in the machine. Most lu-bricants today-both greasesand oils - are manufacturedso as to withstand oxidationand other deteriorating fac-tors for much longer periodsthan was possible only a fewyears ago.

Another important factorin machine tool lubrication iseconomy. How can the besteconomy in lubrication and

maintenance of machine tools be obtained? - By in-telligent lubrication, namely

1. The use of the right product for each require-ment.

2. By applying quality lubricants designed to pre-vent wear and the formation of gum, sludge,

49]

LUBRICATION May, 1949

Figure ! - Automatic lubrication system for oiling this five spindle automatic bar machine manufactured byThe Warner & Swasey Company.

rust or foam, any of which, if permitted to de-velop, can cause excessive maintenance bills.

By making use of a simplified lubrication planto reduce inventories and minimize the possi-bility of costly errors due to a mix-up in productsused.

It is the purpose of this article to present a sim-plified lubrication plan for relatively large groupsof machine tools, to explain recent developmentsin such tools which affect lubrication and to showhow economies may be effected by the use of mod-ern, quality-type lubricants available today.

IMPORTANCE OF EFFECTIVELUBRICATION

Effective lubrication of machine tools meansmuch more than the use of the correct grade oflubricant at the right place in sufficient quantityto adeqt, ately lubricate moving surfaces. It includesalso the use of products which will function overlong periods of time without appreciable changesin theirphysical or chemical characteristics, theuse of efficient filters where necessary to keep outcontaminants, the application of the minimumamount of lubricant necessary to prevent wastage,and other similar factors. Only when all such con-ditions are taken into consideration can lubricationbe assured which will result in continuous trouble-free operation over long periods of time a~ a mini-i~lum cost.

The present era has focussed much more atten-tion on lubrication than ever before. Primarily,this is due to two factors:

(a) The rising cost of maintenance which fa-vors automatic and positive means of re-lubrication.

(b) The development of precision machinescapable of much higher rates of production.

The latter, particularly, has been responsible forincreased attention being given to more carefulselection of lubricants.

It is unnecessary for machine tool operators todetermine the grade of product to be used for eachbearing or gear in all the machine tools he operates.This responsibility, and rightfully so, lies with themachine tool manufacturer and lubricant supplier.In years gone by, many machine tool manufacturersmade no lubricant recommendations at all, or atleast, only very meager ones. Even though this con-dition still exists today with some manufacturers,the majority issue lubrication instructions givingexplicit advice as to proper lubrication of theirmachines. Such instructions are prepared as a re-sult of tests made by the manufacturer, usually incooperation with lubrication engineers from oneor more producers of petroleum products.

Regardless of the diversity of such manufac-turers’ recommendations, in any production plantcontaining numerous machine tools it is necessary

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LUBRICATION

and economical to reduce the total number oflubricants used to an absolute minimum. Manyplants employ a lubrication engineer, and if so,this is his responsibility. In the majority of produc-tion shops, however, no employed lubrication engi-neer is available and in such cases consolidation issponsored by the oil supplier.

One of the factors which has made possible theconsolidated or simplified plan presented herewithis the tremendous advancement made in the qualityof petroleum products during the last decade. Asa result of improvements made in greases, for ex-ample, only one grease is normally employed nowto meet all grease requirements in a specific pro-duction shop. For this reason, as a required pre-requisite to any simplified plan, it is necessary thatthe types of products available today be clearlyknown.

Quality of Lubricants

Modern machine tools equipped with anti-fric-tion bearings and precision gears operating withclose tolerances and at high speeds, are in themajority of cases equipped with splash, bath, orcentralized lubricating systems. Such systems re-quire the use of the highest quality lubricants.Experience has shown that the use of "quality"

products reduces maintenance costs, and improvesmachine performance.

Oils used in reservoirs should be so refined thatthey are highly resistant to oxidation- otherwisegum or sludge may be formed, resulting in un-necessary down time to clean out the machine. Inaddition it is highly desirable that their propertiesbe further fortified by the incorporation of addi-tives. Depending upon the type of oils used andthe properties needed, various present day oilscontain additives to improve oxidation resistance,to prevent rust formation, to overcome foamingdue to entrained air and to increase extreme pres-sure, oiliness, or adhesive qualities.

The acceptance of the use of additives in petro-leum lubricants is shown by the fact that in thelast fifteen years the additive manufacturing in-dustry has grown until now approximately 1,500barrels of additives are produced per day with anannual value of $35,000,000.00. The many benefitsto be derived by the use of additives in lubricantswill be discussed in detail under various ensuingsections.

Cheaper or second grade oils are still used onsome machine tools, particularly machines whichare rather old. Such oils are satisfactory for "oncethrough" lubrication points such as oil cups, oilholes, wick feed and similar oiling methods where

Courtesy oJ Alemit¢ Division, Stewart-Warner Corporation

Hgure 2 -- Portion of a grease dispensing system on a Bullard vertical turret lathe.

[51]

LUBRICATION May, 1949

the oil makes a single pass through the bearing.Even with older machines predominantly lubri-cated by oil cups, however, it is often desirable touse quality lubricants. Such machines are usuallyin a minority in any given shop and stocking oftwo oils of the same viscosity, one a high grade forreservoirs and the other a cheaper grade for oilcups, proves more expensive in the long run.

Viscosity

The importance of using the correct viscosity orgrade of oil cannot be overstressed in the lubrica-tion of modern precision machine tools. In oldermachines, or in tools which do not produce workto close tolerances, viscosity is less important andoils with a rather wide range of viscosities may beused with entire satisfaction.

On close fitting parts used so prevalently inmodern tools the viscosity should be kept withinthe limits specified by the manufacturer. Obviously,it should not be so low that metal to metal contactmight occur. The use of an oil having too high aviscosity also has several disadvantages. Internalfriction developed in the oil can cause it to over-heat, resulting in more rapid oil deterioration andheating up of the metal parts surrounding the oil.The latter is particularly troublesome on machinesworking to very close tolerances for the excessiveheat generated may be sufficient to expand theframe of the machine, or parts thereof to such anextent that the cutting tools or work must be resetperiodically.

Courttsy o[ Th¢ Farral Corporation

Figure 3 -- Centralized oiling system on a Mitts & Merrill No..SKey Seater.

Courtesy of Man:el Inc.

Figure 4 -- A four feed automatic lubricator used to lubricatethe ways of this knife grinder manufactured by Samuel C.

Rogers & Co.

SIMPLIFIED LUBRICATION PLAN

Simplification and economy are intimately re-lated in so far as the lubrication of machine toolsis concerned.

Progressive machine tool operators are constant-ly endeavoring to reduce the total number of lubri-cants required for the proper lubrication of theirmachines. This has been influenced in recent yearsby several factors, including the increasing cost ofmaintenance, the necessity of reducing overheadexpenses and primarily, the availability of newertypes of lubricants which are capable of function-ing under wide varieties of conditions.

The primary purpose of this article is to presenta simplified lubrication plan for machine tools.This plan takes into account all of the above fac-tors. Briefly, it presents a method for consolidatingthe number of lubricants used in a given produc-tion shop to an absolute minimum. Specifically, theproducts recommended in this plan are shown inTable I.

This consolidated or simplified list of lubricantsfor large production shops, was developed as aresult of a study of all machine tool manufacturers’lubricant recommendations and extensive field ex-perience obtained with the types of products recom.mended. This list will apply to the great majorityof machine tools in use today. (In a few instances,however, specialty products may be required.)Even all the products listed may not be necessaryin a given production shop; for example, the useof two greases, two hydraulic oils or several waylubricants and spindle oils may be unnecessary.

In order that the recommendations made maybe understood more clearly each is discussed indetail in the following sections.

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LUBRICATION

~ ~ ~ oo oo ~ ~Z Z

[~]

LUBRICATION May, 1949

Figure 5 -- Schematic p/an of hydraulic and lubricating

Hydraulic SystemsProbably nowhere on a machine tool can trouble

occur as often as in the hydraulic system if acceptedmaintenance procedures are not followed. Theseinclude the use of the correct grade of oil with aquality commensurate to demands placed on theoil by the hydraulic system.

Many factors contribute to the need of specialcare in selecting hydraulic oils. Conditions whichcause oils to oxidize present one of the foremost.These conditions include operating temperaturesranging up to 150° F. or even higher in a fewinstances, severe agitation at each pass throughpumps and valves, pressure, the presence of metal-lic catalysts and unfortunately in some instancesvarious contaminants such as cutting oils. As aresult, inhibitors are now incorporated in hydraulicoils to retard oxidation; their effectiveness beingphenomenal. Field experience has shown that in-tervals between drain periods may be increasedmany times over that obtained with straight mineraloils, and more important the possibility of gum orsludge formation in the system is almost entirelyeliminated.

Rust formation in hydraulic systems is anotherfactor contributing to poor hydraulic system per-formance. Rust can be caused by condensation ofmoisture in the reservoir, contamination such asfrom coolants, or leaking water coolers. Fortunate-ly, rust formation can be prevented by the additionof small amounts of inhibitors to the oil. These

Courtesy o] Norton Company

system of a 6" Type C Cylindrical Grinding Machine.

inhibitors "plate out" on metal surfaces, forminga film which is impervious to the rusting action ofmoisture and air.

A third factor is foaming, which is troublesomein some systems. Here again, it is possible to sotreat or process the oil that any entrained air in theoil is quickly separated. The presence of air inhydraulic oils can result in erratic motion of actu-ated parts, can cause the oil to oxidize more rapidlyand if foam is formed in the reservoir the probableoverflow is unsightly and a safety hazard.

During the last several years the economy ofusing high quality inhibited type hydraulic oils hasbeen proven time and time again. Little wonderthey are used almost exclusively today in machinetool hydraulic systems.

Mention has previously been made that viscosityis an important consideration in the selection ofoils. Since pumps are the most critical part of ahydraulic system in so far as lubrication is con-cerned, pump manufacturers have made extensivetests to determine what viscosity oil performs bestin systems containing their pumps. It is necessarythat the viscosity be sufficiently high to preventmetal to metal contact and to give high volumetricefficiencies, yet it must be low enough to pumpeasily so that pressure drop through the system isat a minimum. For these reasons pump manufac-turers issue specifications indicating the correctviscosity to be used under various operating con-ditions.

[ 54]

LUBRICATION

Fortunately, practically all hydraulic pumps usedon machine tools require the use of two grades orviscosities of oil, one being 150 and the other ap-proximately 300 seconds at 100° F. Say. Univ. Forthis reason, two grades of hydraulic oil are shownin Table I, but perhaps only one may be necessaryin a given production shop.

General Machine LubricantRelegated to history is the general use of oil

holes, oil cups or other manual means of applyingoil to modern production machine tools. In theplace of such devices centralized pressure, splashor similar forms of lubrication are now almost uni-versally accepted. The great majority of productionmachines built today are so lubricated that little orno attention is required at time intervals rangingfrom a minimum of once a shift to long periods oftime. Even machines lubricated once each shift arefor the most part equipped with so called "oneshot" systems where it is necessary merely to pullout a knob to relubricate the machine.

Centralized systems range from "one shot" tocompletely automatic systems in which it is merelynecessary to periodically replenish the reservoirwith oil. Applications of such systems to machine

tools are shown in the illustrations accompanyingthis article.

Even though automatic lubrication is a featureof almost all production machines, remote spotswhich cannot otherwise be lubricated economically,may require application of oil by sight feed oilersor oil cu~s. These must not be overlooked whenrelubricat~ng.

Just as the use of automatic lubricating systemshas become so common during the last few years,so has the use of inhibited lubricating oils forgeneral machine lubrication. In fact some opera-tors have found that using inhibited hydraulic oilsfor general machine lubrication has saved themmoney in maintenance and down time costs. Onereason is that rusting is a detrimental factor inhumid atmospheres and of course this can be over-come by the use of rust inhibited oils. The pos-sibility of gum or sludge formation as the result ofoil oxidation, and foaming caused by air beingbeaten into the oil are other detrimental factorswhich can be overcome by using inhibited oils in-stead of straight mineral oils.

A fourth type of additive currently coming intospecialized usage imparts extreme pressure char-acteristics. Oils containing such additives are now

Courtesy of Trabor Engineering Corporation

Figure 6- Centralized grease lubricating system on a turret lathe. Note pump and reservoir located inlower right hand corner and mounted in a horizontal position.

[55]

LUBRICATION May, 1949

Courtes7 of Bijur Lubricating Corp.

Figure 7--Automatic oiling system for a thread generatormade by The Fellows Gear Shaper Company.

Gears Other Than Those Lubricated by

the General Machine Lubricant

Some machine tools are equipped with gearswhich require a much higher viscosity productthan that used as a general machine lubricant.Typical ex~mpIes are found on some back gears ofvertical or larger type horizontal turret lathes,column mechanisms’ of milling machines, screwmechanisms on boring mills, etc. Such productsusually fall within the SAE-90 or 140 viscositygrade, and the specific viscosity and type of prod-uct required is normally specified by the machinebuilder.

Gear lubricants in so far as type is concerned,fall within two classifications, straight mineral oiland extreme pressure lubricants. Straight mineraloil type gear lubricants should be well refined andhighly resistant to oxidation. In addition, theyshould be so processed that they do not foam whenmixed with air, or emulsify when contaminatedwith water.

With r.espect to extreme pressure gear lubricants,the lead soap base type has been outstanding. This

~PmeiS non-corrosive to copper or steel, has a highstrength, is unaffected by presence of moisture

and does not thicken or oxidize appreciably inservice. Lead soap base extreme pressure lubricants

specified by several manufacturers whose tools con-tain heavily loaded bearings. Typical types of ma-chine tools include some grinders for crush dress-ing, centerless thread grinders, and vertical turretlathes.

The great majority of machine tools require theuse of a general machine lubricant having a vis-cosity of approximately 300 or 500 seconds Say.Univ. at 100° F. However, certain tools, may re-quire an oil having a viscosity of only 200 secondsat 100° F. In general the lower the viscosity, theless will be the heat generated by internal frictionin the oil. Low viscosity oils are used where dis-tortion of machine parts, caused by oil heating,must be minimized.

Based on present indications there are certaindefinite trends in general machine lubrication, i.e.

(1) the ever increasing use of automatic lubri-cating systems

(2) general acceptance of machine lubricantscontaining inhibitors to prevent oil oxida-tion, rust and foaming

(3) an increase in the use of extreme pressureagents in oils for use on certain types ofmachines

(4) a general lowering in the viscosity of theoil used as machines tolerances are de-creased.

Courtesy of The Farval Corporation

Figure 8 - A centralized oiling system on a special horizontaldrum type Barnes drill.

LUBRICATION

are recommended for use on all types of gears,including worm gears, for use on anti-frictionbearings contained in the gear case, on screws, andsimilar applications. For these reasons, this typeis often used where both straight mineral and ex-treme pressure gear lubricants are specified byvarious manufacturers for their tools in a specificproduction shop in order to simplify the numberof products used.

Sulfur-chlorine, "mild" type extreme pressure lu-bricants can also be used on gears but before doingso it should be ascertained if they are corrosive, orwill stain steel or copper.

Gear lubricants are normally contained in reser-voirs, the gears being lubricated by splash or by aforced feed system. A few specialized machinescontain what are termed open gears, that is, theyare not contained in an oil tight housing. In suchcases, it is necessary that an adhesive type gearlubricant be applied directly to the gears. Suchproducts are made from heavy residual stocks andare su~ciently adhesive and cohesive that they willnot throw off.

SpindlesHigh speed spindles on grinders and similar

types of tools require extreme care in the selection

Courtesy ol Sundstrand Machine Tool Co.

Figure 10--Automatic lubrication for gear train and spindlein a No. 33 Rigldmill. The oll pump actuated by an eccentricon the lower shaft delivers oil to the header from which i~ isdelivered to individual bearings by tubing as indicated. Notethe flow gage through which vlsual observation will show that

the distribution system is functioning properly.

Courtesy of Kearney & Trecker Corp.

Figure 9 -- Illustrating how one milling machine is lubricatedby force feed from three reservoirs. In each case the oil is

circulated to points of application by small pumps.

of the proper lubricant. Spindles may be eithergrease or oil lubricated depending upon the design.

With respect to oil lubricated spindles, speedand load on the bearings are two primary con-siderations in the selection of a proper lubricant.Other factors, however, such as the type of bearinginvolved, possibility of contaminants (grindingdust for example) entering the bearing housingand method of lubricant application also play animportant part in the choice of a lubricant.

It is absolutely essential that there be no playin spindles, therefore, clearances are held to aminimum. Also, there has been a definite trendtoward higher spindle speeds. As clearances aredecreased and speeds increased, it is normallynecessary that the viscosity of the lubricant belowered. It is for this reason that some manufac-turers specify very low viscosity oils for spindles.

The reasons for using low viscosity products onmodern high speed spindle bearings is simply thatif high viscosity products were used, the bearingsmight overheat and ultimately seize, the hot oilwould oxidize more rapidly and the hot metal sur-rounding the oil would expand, thus affecting theaccuracy of the machine.

Spindle bearings range in design all the wayfrom sleeve type bearings to three part bearings(half box located at the bottom and to the rear of

[~]

LUBRICATION May, 1949

the spindle housing with two adjustable bearingsegments on top), three or five pivoted shoe typesand, of course, anti-friction bearings.

Methods of oil lubrication range from the useof sight feed oil cups, spring-actuated wick oilersand ring oilers to flood lubrication and mist appli-cation.*

Oil lubricated spindles require products rangingin viscosity from 40 to 300 seconds at 100° F.,Say. Univ. depending upon factors discussed above.Although general recommendations can be made,as indicated below, it is best to follow the manu-facturers’ recommendations as to the correct vis-cosity of oil to use in a specific spindle. In generalsight feed oilers, wick oilers, and ring oilers areto be found on comparatively low speed spindles,whereas flood and mist type lubrication are usedon higher speed bearings, with mist being used atvery high speeds. Therefore, based on method ofoil application the following very broad recom-mendations can be made:

General ViscosityRange of Oil, Say.

Method of Oil Univ. Seconds atApplication 100° F.

Sight feed oilers 100- 2OO

Spring-actuated wick feed 100- 200

Ring oiled 200 - 300Flood or circulating 40- 300Oil Mist 50- 150

In systems where the oil is circulated to the bear-ings and back to a reservoir (ring oiled, splash,flood or force feed) it is essential that the productused be of good quality. The oil must be resistantto oxidation, not emulsify with any water of con-densation or contamination, and quickly free itselfof any entrained contaminants, such as grindingdust. In both circulating systems and with mistlubrication, when applied to anti-friction bearings,it has been found that rust is sometimes a factorwhich can cause serious bearing damage. In orderto overcome this, rust inhibited oils have beenresorted to with complete success.

So far, this discussion has concerned oil lubri-cated spindles only. However, where there is apossibility of oil leakage, or under conditions wheredirt, dust and other contaminants can get into thebearing, grease is often used. In such cases, a pre-mium grade anti-friction bearing grease of a No. 2NLGI consistency, such as described in the sectionto follow on "Greases", should be used.

No discussion on spindle lubrication would becomplete without a word on cleanliness. High

*Spindle design and methods of oil application ha~,e been .dis-cussed in more detail in two previous issues of Magaztne Lubrica-tion; July 1948--"Metals Grmding Machinery Lubrication", andSeptembe~ 1948--"High Speed Ball Bearing Lub~icafioa".

Courtesy of Cincinnati Milling andGrinding Machines, Inc.

Figure 11 -- Lubricating lines in the saddle of a No. 2 Cutterand Tool Grinder, with table removed. Oil is fed to the dis-tributor in the center from which it goes to various bearings.

speed spindle bearings can be ruined by smallparticles of dirt. For this reason, air used in mistlubrication should be filtered to remove entraineddirt and moisture. Every effort should be made,also, to keep contaminants out of circulating oilsand if the oil does become contaminated, it shouldbe changed immediately.

WaysNo matter how well a machine tool is designed,

if the ways are not properly lubricated accuratemachining cannot be accomplished. Off hand, onewould think it simple to lubricate two flat or Vshaped surfaces upon which a carriage, turret orwork rest must ride. Quite to the contrary, how-ever, this is one of the critical points in machinetool lubrication and a great deal of research hasbeen conducted by both machine builders and oilsuppliers on this problem. As a result of some ofthis work, new "special" way lubricants have beendeveloped recently and are receiving ever increas-ing acceptance.

One of the primary problems encountered onmany machine ways was chattering, which causedirregularities in the work being done. Since chat-tering normally occurs just after motion has beenreversed, the most common theory was that on theforward motion oil was wiped off the way, thenas motion was reversed the carriage had to traversea comparatively dry way before the oil supplycould be replenished. Another problem was thatif the carriage was stopped the lubricant had atendency to press out with the result that whenthe carriage was again moved it occurred in a"stick-slip" motion. Chattering predominates onsome milling, shaping, grinding and similar typemachines where the carriage goes back and forth

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LUBRICATION

at predetermined cycles. "Stick-slip" motion is ofprimary concern on such equipment as lathes wheretools at times are advanced into the work a fractionof an inch.

In addition to overcoming the above problems,a way lubricant must have other properties. Toenumerate the more desirable qualities:

1. It should eliminate chatter.

2. It should not press out upon standing.

3. It should contain oiliness and extreme pres-sure agents to prevent metal to metal contactbetween localized high spots.

4. The oil film thickness built up should not besufficiently thick to affect the accuracy of thework being done.

5. It is essential that it be non-corrosive to steelor the copper found in the oil distributionsystem.

6. It should not plug felt filters found in somecentralized systems.

7. It should not wash off or be adversely affectedby cutting fluids, coolants or water.

Way lubricants having all the above desirablequalities have been developed and placed on themarket in the last several years. Where chatteringor "stick-slip’" troubles have been encountered withstraight mineral oils, oils compounded with fattymaterial or even lead soap base gear lubricants,these troubles have been eliminated by the use of"special" way lubricants.

A variety of type of lubricants may be used onways, depending both on the load and method oflubrication. Where loads do not exceed approxi-mately 10 pounds per square inch, a straight min-eral oil having a viscosity of about 300 seconds at

100° F. Say. Univ. is used, unless the machine man-ufacturer specifies a somewhat heavier grade.

When loads are above 10 lbs. per sq. in. it isusually necessary to use a high viscosity straightmineral oil, or more often, a fortified mineral oil.In the past compounded oils, containing fatty ma-terial which increases "oiliness", and various typesof extreme pressure gear lubricants have been used,with success ranging from good to only fair. It isconfidently believed, however, that the machinetool industry will standardize on the use of specialway lubricants such as the type described at thebeginning of this section when something morethan a straight mineral oil is required.

Cross slide ways and comparatively short waysmay be lubricated through oil cups, or by similarmetho.ds, but longer ways are almost universallylubricated through "one shot" or other forms ofa centralized distribution system. Most are auto-matic so that on each stroke the ways receive ashot of oil.

Ways on some machines are lubricated from thehydraulic system or headstock. In such instances,small diameter copper tubing conducts the oil fromthe hydraulic circuit or headstock to the ways. Itis necessary that the lubricant serve the dual pur-pose of hydraulic or headstock and way lubricatingoil. At the present time only some light duty ma-chines are designed in this manner and the choiceof a suitable lubricant requires specialized atten-tion. In a few instances ways are lubricated byexcess cutting fluid splashing on the ways.

GreasesModern machine tools are predominantly oil

lubricated, however, grease is used on electricmotors, coolant pumps, on some spindle bearingsand on miscellaneous applications such as togglemechanisms, sliding surfaces (other than ways)and some inaccessible bearings.

WHEELHEAD WAYS

K----FLAT

’11

.I |....mm .. -- .m mJrm~¯ TABLE t VEE"WAYS

[irlt.FLAT

Courtesy ol Cincinnati Milling and Grinding Machines, Inc.

Figure 12 -- Diagram of lubrication system on ways of a 4" Plain Hydraulic Grinder.

[59]

LUBRICATION May, 1949

Experience has shown it is generally desirableto stock only one grease for all grease applicationsand in such instances, the type of grease used isdictated by the requirements o~ high speed greaselubricated spindles or electric motors. In theseapplications a premium grade No. 2 NLGI greasecontaining a sodium-calcium mixed base soap, amineral oil with a viscosity of 150 to 400 secondsat 100° F. Say. Univ. and an inhibitor to retardoxidation is used. Such a product has proven en-tirely satisfactory on high speed anti-friction bear-ings such as found on spindles and electric motorsand at continuous operating temperatures up toat~out 250° F. In a few cases, on particularly largeor heavy duty equipment a sodium soap base greasecontaining a high viscosity oil is required, for sucha product will withstand heavier loads than willthe type recommended for electric motors andspindles.

On many older machines, plain bearings wereused extensively and for these an ordinary cupgrease was used. Even though many of these ma-chines are still in operation, most operators nowuse the type of grease required for anti-frictionbearings (described above) for such points. It often found more economical to carry only onegrease for all grease lubricated points rather thantwo greases, one for anti-friction bearings and acup grease for plain bearings. Some operators havegone so far as to say that the mere possibility ofexchanging these two types, resulting in the almostcertain failure of high speed anti-friction bearingsis sufficient reason to preclude the stocking of acup type grease for plain bearings.

The application of grease on modern machinetools has been greatly simplified. In the past it wasnecessary to completely circle the machine to reachall points. The modern trend is definitely towardthe use of a centralized distribution system (seeaccompanying illustrations) or, at least to supplya centralized panel ecjuipped with pressure greasefittings and connected to various bearings by suit-able tubing, thus making it almost impossible tomiss an isolated bearing.

Dual or Tri-Purpose OilsNo simplified lubrication plan for machine tools

would be complete without consideration of aspecial problem which arose in the case of somemultiple spindle bar and chuck type automaticscrew machines. This problem related to the main-tenance of the correct cutting oil in these machinesfor it was found in some instances the machine’slubricant, and sometimes the hydraulic oil, were

diluting the cutting oil in sufficient volume to re-duce the active ingredients in the cutting oil. In afew instances, the direction of the dilution wasreversed; in these cases, the cutting oil being theoffender by contaminating the lubricating and/orhydraulic oil, thus resulting in sludge formation,corrosion and ultimately ruined machine parts.

To overcome this situation "Dual Purpose Oils"were developed which could be used as a generalmachine lubricant as well as the cutting fluid onbar type automatics. Subsequently, their use wasextended to the hydraulic system on chuck typeautomatics, resulting in their accepted dassificationas "Tri-Purpose Oils".

Dual or Tri-Purpose Oils are non-corrosive tosteel or copper. Years of experience has shownthem to function efficiently as a machine lubricantand a hydraulic fluid in these systems. In addition,they give excellent tool performance on all ma-chining operations which are considered mild orslightly on the tough side. Even on "tough" jobsthe effect of dilution from that portion used in thelubricating system will be far less than if straightmineral oil had been used in the latter.

Warning:-It is absolutely essential that onlyfresh clean oil be added on the lubricating side ofthe machine. Oil from the cutting oil sump shouldnever be added to the lubricating oil reservoir forif it is, the chips in the latter would soon causeserious damage to the bearings.

CONCLUSIONMachine tool manufacturers are to be compli-

mented on the ever increasing attention beinggiven to lubrication. Many manufacturers have de-voted a great deal of time and effort in order todetermine the most satisfactory grades of lubri-cants to be used; they are very conscious of theirresponsibility to their customers in passing thisinformation on to them.

Machine tool manufacturers also are designingmodern tools so that a minimum of attention canbe given re-lubrication. Methods used include thealmost universal acceptance of centralized lubri-cating system with their many advantages of posi-tive lubrication and savings in labor and mainte-nance costs.

The Petroleum Industry, too, is proud of thelubricants developed in recent years which makeit possible to use a single product over an everbroadening range of conditions. Modern lubricantsalso function over much longer periods of time.Such lubricants permit the development of a sim-plified lubrication plan as described in this article.

Printed in U. $. A. bySalle~_& Collins, Inc.30.~ East 45th StreetN~w York 17. N. Y.

TEXACO LUBRICANTSFOR MACHINE TOOLS

Parts to be Lubricated

HYDRAULIC SYSTEM

Low Viscosity ................................................

Medium Viscosity .............................................

GENERAL MACHINE LUBRICANT

Low Viscosity ................................................

Medium Viscosity .............................................

High Viscosity ................................................

GEARS (Not lubricated by general machine oil)

Lightly Loaded- Other Than Worm ............................

Heavily Loaded- Other Than Worm ...........................

All Worm Gears ..............................................

SPINDLES

Oil Lubricated

By Oilers and Wick Feed ...................................

By Ring Oiler ....................... ~ ......................

By Circulating or Flood System ............................

By Oil Mist ................................................

Grease Lubricated ............................................

WAYS

Lightly Loaded

Medium Viscosity ..........................................

High Viscosity .............................................

Heavily Loaded or Where Chattering Occurs

Medium Viscosity ..........................................

High Viscosity ............................................

GENERAL GREASE LUBRICATION

Normal Operation ............................................

Texaco Recommendations

Texaco Regal Oil A (R&O)

Texaco Regal Oil PC (R&O)

Texaco Regal Oil B (R&O)

Texaco Regal Oil PC (R&O)

Texaco Regal Oil PE (R&O)

Texaco Thuban 90 or 140

Texaco Meropa Lubricants--3 or 6

Texaco Meropa Lubricants--3 or 6

Texaco Regal Oils (R&O)

Texaco Regal Oils (R&O)

Texaco Spindura or Regal Oils (R&O)

Texaco Spindura or Regal Oils (R&O)

Texaco Regal Starfak No. 2

Texaco Regal Oil PC (R&O) or PE (R&O)

Texaco Ursa Oil

Texaco Way Lubricant

Texaco Way Lubricant

Texaco Regal Starfak No. 2

Heavy Duty Operation ........................................ t Texaco Marfak No. 1, or MarfakNo. 2 Heavy Duty

DUAL AND TRI PURPOSE OILS FOR MULTIPLE

SPINDLE AUTOMATIC SCREW MACHINES

Dual Purpose -- Machine Lubricant and Cutting Fluid ............. Texaco Cleartex Cutting Oil B

Tri Purpose -- Hydraulic Fluid, Machine Lubricant and Cutting Fluid Texaco Cleartex Cutting Oil DD

The foregoing products are of highest quality and are recommended for use where automatic or circulatingsystem primarily prevail, as they do on most modern machines.

Texaco Lubrication Engineers are thoroughly familiar with the Simplified Lubrication Plan for MachineTools. Let them help you simplify the number of lubricants used in your production shops.

CutYou

metal curtUse Texaco Cutting Coolants For FasterMachining, Finer Finish, Fewer Rejects

Drilling, grinding, milling, turning --whatever the metal or machining method

-- there is a top-quality Texaco Cutting,

Gri~dbtg or Soluble Oil to help you do

every metal cutting job in your plant faster,

better, and at minimum cost.

Texaco Cutting, Grinding attd Soluble

Oils lubricate effectively. They keep tool

and work cool -- prevent chip welding or

wheel loading. They prolong tool life,

assure cleaner cuts and smoother finish, in-

crease production and lower costs wherever

they are used.

A Texaco Lubrication Engineer who spe-

cializes in cutting coolants will gladly help

you select-and use effectively--the Texacocutting coolants you need for best results.

Just call the nearest of the more than

2300 Texaco Wholesale Distributing Plantsin the 48 States, or write The Texas Com-

pany, 135 East 42nd Street, New York 17,

New York.

THE TEXAS COMPANYATLANTA, GA... 864 W. Peachtree StreetBOSTON 17, MASS.. 20 ’Providence StreetBUFFALO 3, N.Y. . 14 Lafayette SquareBUTTE, MONT.. 2"20 North’ Alaska StreetCHICAGO 4, ILL.. 332 So. Michigan AvenueDALLAS I, TEX. . . 311 South Akard StreetDENVER 1, COLO.... ~ ~ ~ 910 !6th Street

sr~rrLe ,1 t, wA.sx.

¯ TEXACO PRODUCTS * DIVISION OFFICESHOUSTON 1, TEX... 7’20 San Jacinto StreetINDIANAPOLIS 1, IND., 3521 E. Michigan StreetLOS ANGELES 15, CAL. . 929 South BroadwayMINNEAPOLIS 2, MINN. . 300 Baker Bldg.NEW ORLEANS 6, LA., 919 St. Charles StreetNEW YORK 17," N.Y.. 205 East 42nd StreetNORFOLK 1, VA. . Olney Rd. & Oranby St.

::,.. 1~!1 Third Avenue

Texaco Producl~ dbldlmted throug ,kaut.Canada by M~oll-Front~nac Oil Company, Umlted, MONTREAL, CANADA