common machining processes
TRANSCRIPT
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Common Machining Processes
FIGURE 8.1 Some examples of common machining processes.
(c) Slab milling (d) End milling
End mill
Cutter
(b) Cutting off(a) Straight turning
ToolTool
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Orthogonal Cutting
FIGURE 8.2 Schematic illustration of a two-dimensionalcutting process, or orthogonal cutting. (a) Orthogonal cutting
with a well-defined shear plane, also known as the Merchantmodel; (b) Orthogonal cutting without a well-defined shear
plane.
Rake angle
Chip
Tool face
V Flank
Relief orclearanceangle
Shear angle
Shear plane
!
Tool
Shiny surfaceRough surface
Workpiece
to
tc
- +
"
(a)
Chip
Roughsurface
Primary
shear zone FlankRelief orclearanceangle
Tool face
Tool
tc
to
V
- +
"
Rake angle
(b)
Rough surface
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Chip Formation
FIGURE 8.3 (a) Schematic illustration of the basic mechanism of chip formation in cutting. (b) Velocitydiagram in the cutting zone.
Shearplane
Workpiece
d
Chip
Tool
A
C
B
AC
BO
Rake angle,A
(b)
Vc
Vs
V
(a)
(90 -A)
(90 -F+A)
(F-A)
(F-A)
F
F
A
F
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Hardness in Cutting Zone
FIGURE 8.6 (a) Hardness distribution in the cutting zone for 3115 steel. Note that some regions in the built-up
edge are as much as three times harder than the bulk workpiece. (b) Surface finish in turning 5130 steel with abuilt-up edge. (c) Surface finish on 1018 steel in face milling. Source: Courtesy of Metcut Research Associates, Inc.
(a)
(b)
(c)
474
661
588
492
588
656 604
684
565
432589
656 567 578
512704
704 639
655770734
466
587704
372306
329
289325
331286289
371 418
383
306386
261
565327
361281
289
410341
281308
231
201
251266
317229
377503544409297
316
230
Workpiece
Built-upedge
Hardness (HK)
Chip
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Chip Breakers
FIGURE 8.7 (a) Schematic illustration of the action of a chip
breaker. Note that the chip breaker decreases the radius ofcurvature of the chip. (b) Chip breaker clamped on the rake face of
a cutting tool. (c) Grooves on the rake face of cutting tools, acting
as chip breakers. Most cutting tools now are inserts with built-inchip-breaker features.
(a) (b)
Workpiece
Tool
After
Chip
Before
Chip breaker
Rake face
of tool
Tool
Clamp
Chip breaker
(c)
Positive rake
Rake face
0 rakeRadius
FIGURE 8.8 Various chips produced inturning: (a) tightly curled chip; (b) chip hitsworkpiece and breaks; (c) continuous chip
moving radially outward from workpiece; and(d) chip hits tool shank and breaks off. Source:
After G. Boothroyd. (a) (b) (c) (d)
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Oblique Cutting
FIGURE 8.9 (a) Schematic illustration of cutting with an oblique tool. (b) Top view, showing theinclination angle, i. (c) Types of chips produced with different inclination angles.
Workpiecei= 30
i= 15
i= 0
Chip
(a) (b) (c)
i
a
o
Tool
Top view
Workpiece
i
a
o
Tool
Chip
y
z
x
Ac
At
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Right-Hand Cutting Tool
FIGURE 8.10 (a) Schematic illustration of a right-hand cutting tool for turning. Although thesetools have traditionally been produced from solid tool-steel bars, they are now replaced by inserts
of carbide or other tool materials of various shapes and sizes, as shown in (b).
(a) (b)
End-cuttingedge angle
(ECEA)
Side-rakeangle, + (SR)
Axis
Axis
Cutting edge
Face
Back-rake angle, + (BR)
Nose radiusFlank
Side-relief angle
Side-cutting edge angle (SCEA)
Clearance or end-relief angle
AxisS
hank
InsertClamp
Clamp screw
Toolholder
Seat or shim
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Cutting Forces
FIGURE 8.11 (a) Forces acting on a
cutting tool in two-dimensional cutting.Note that the resultant forces, R, must be
collinear to balance the forces. (b) Forcecircle to determine various forces acting
in the cutting zone. Source: After M.E.Merchant.
Chip
Tool
Workpiece
(a) (b)
Fn
Fc
Fs
Ft
R
F
N
R
Chip
V
V
Tool
Workpiece
Fc
Fs
FtF
N
R
A
A
A
B
BA
BF
F
Cutting force Friction coefficient
Fc = Rcos() = wtocos(
)
sincos(+)= tan= Ft+Fc tan
FcFttan
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Cutting Data
FIGURE 8.12 Thrust force as a function of rake
angle and feed in orthogonal cutting of AISI 1112
cold-rolled steel. Note that at high rake angles, thethrust force is negative. A negative thrust force hasimportant implications in the design of machine
tools and in controlling the stability of the cuttingprocess. Source: After S. Kobayashi and E.G.
Thomsen.
! = 5
10
15
20
25
30
35
40
0 0.1 0.2 0.3
mm/revmm/rev
800
400
0
2200
(N)
Ft(lb)
200
150
100
50
0
2500 0.002 0.004 0.006 0.008 0.010 0.012
Feed (in./rev)
ut(in.-lb/in3 uf/ut
Fc (lb) Ft (lb) 103) us uf (%)
25 20.9 2.55 1.46 56 380 224 320 209 111 3535 31.6 1.56 1.53 57 254 102 214 112 102 4840 35.7 1.32 1.54 57 232 71 195 94 101 5245 41.9 1.06 1.83 62 232 68 195 75 120 62
to = 0.0025 in.; w = 0.475 in.; V = 90 ft/min; tool: high-speed steel.
uf/ut V Fc Ft ut us uf (%)
+10 197 17 3.4 1.05 46 370 273 400 292 108 27400 19 3.1 1.11 48 360 283 390 266 124 32642 21.5 2.7 0.95 44 329 217 356 249 107 30
1186 25 2.4 0.81 39 303 168 328 225 103 31-10 400 16.5 3.9 0.64 33 416 385 450 342 108 24
637 19 3.5 0.58 30 384 326 415 312 103 251160 22 3.1 0.51 27 356 263 385 289 96 25
to = 0.037 in.; w = 0.25 in.; tool: cemented carbide.
TABLE 8.1 Data on orthogonal cutting of 4130 steel.
TABLE 8.2 Data on orthogonal cutting of 9445 steel.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Shear Stress on Tool Face
FIGURE 8.14 Schematic illustration of the distribution of normal and shear stresses at the tool-chip interface(rake face). Note that, whereas the normal stress increases continuously toward the tip of the tool, the shearstress reaches a maximum and remains at that value (a phenomenon known as sticking; see Section 4.4.1).
!
"
Tool face
Sliding
Sticking
Stresses on tool face
Tool tip
Tool
Flank face
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Shear-Angle Relationships
FIGURE 8.15 (a) Comparison of
experimental and theoretical shear-anglerelationships. More recent analyticalstudies have resulted in better agreement
with experimental data. (b) Relationbetween the shear angle and the friction
angle for various alloys and cuttingspeeds. Source:After S. Kobayashi.
50
40
30
20
10
0230 220 210 0 10 20 30 40 50 60
Lead
Copper
Tin
Eq.(8.21)
Eq.(8.20)
Mild steel
Alum
inum
(! - ")
Shearangle,
#(
deg
.)
" = 0
! = 10 30 50 70 (deg.)
=0 0.5 1 2
60
40
20
0
#(
deg.)
(a) (b)
Merchant [Eq. (8.20)]
Shaffer [Eq. (8.21)]
Mizuno [Eqs. (8.22)-(8.23]
= 45+
2
2
= 45+
= for > 15
=
15
for < 15
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Specific Energy
Specific Energy
Material W-s/mm3 hp-min/in3
Aluminum alloys 0.4-1.1 0.15-0.4Cast irons 1.6-5.5 0.6-2.0Copper alloys 1.4-3.3 0.5-1.2High-temperature alloys 3.3-8.5 1.2-3.1Magnesium alloys 0.4-0.6 0.15-0.2Nickel alloys 4.9-6.8 1.8-2.5
Refractory alloys 3.8-9.6 1.1-3.5Stainless steels 3.0-5.2 1.1-1.9Steels 2.7-9.3 1.0-3.4Titanium alloys 3.0-4.1 1.1-1.5 At drive motor, corrected for 80% efficiency; multiplythe energy by 1.25 for dull tools.
TABLE 8.3 Approximate Specific-Energy Requirements in
Machining Operations
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Temperatures in Cutting
40
0
500
450
Workpiece
Tool
Chip
3080
130
380
600
360
500
600
650
7
00
Temperature (C)
65
0
600
FIGURE 8.1 Typical temperaturedistribution in the cutting zone. Note the
severe temperature gradients within the
tool and the chip, and that the workpiece isrelatively cool. Source:After G. Vieregge.
200
300
V=550ft/min
Work material: AISI 52100
Annealed: 188 HB
Tool material: K3H carbide
Feed: 0.0055 in./rev
(0.14 mm/rev)
0 0.5 1.0 1.5
mm
700
600
500
400
C
0 .008 .016 .024 .032 .040 .048 .056
Distance from tool tip (in.)
1400
1300
1200
1100
1000
900
800
700
Flanksurfacetemperature(F
)
(a)
550
ft/min
300
200
2000
1800
1600
1400
1200
1000
800
600
400
Localtemperatureattool-chipinterface(F)
0 0.2 0.4 0.6 0.8 1.0
Fraction of tool-chipcontact length measured
in the direction of chip flow
1100
900
700
500
300
C
(b)
FIGURE 8.2 Temperature distribution in turning as a function of cutting speed:(a) flank temperature; (b) temperature along the tool-chip interface. Note that
the rake-face temperature is higher than that at the flank surface. Source: After
B.T. Chao and K.J. Trigger.
T=1.2Yf
c
3
Vto
K
FIGURE 8.18 Proportion of the heat generated in cutting transferred to the
tool, workpiece, and chip as a function of the cutting speed. Note that most ofthe cutting energy is carried away by the chip (in the form of heat), particularly
as speed increases.
Work
piece
Cutting speed
Energy(%)
Tool
Chip
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Terminology in Turning
FIGURE 8.19 Terminology used in a turning operation on a lathe, where fis the feed (in mm/rev or in./rev) anddis the depth of cut. Note that feed in turning is equivalent to the depth of cut in orthogonal cutting (see Fig.
8.2), and the depth of cut in turning is equivalent to the width of cut in orthogonal cutting. See also Fig. 8.42.
Depth of cut(mm or in.)
Feed(mm/rev or in./rev)
Tool
Chip
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Effect of Workpiece on Tool Life
FIGURE 8.21 Effect of workpiece microstructure on tool life in turning. Tool life is given in terms of the time
(in minutes) required to reach a flank wear land of a specified dimension. (a) Ductile cast iron; (b) steels, withidentical hardness. Note in both figures the rapid decrease in tool life as the cutting speed increases.
Hardness
(HB) Ferrite Pearlite
a. As cast
b. As cast
c. As cast
d. Annealed
e. Annealed
265
215
207
183
170
20%
40
60
97
100
80%
60
40
3_
50
100 300 500 700 900
100 150 200 250
0
40
80
120
m/min
Cutting speed (ft/min)
Toollife(min) a
b cd
e
(a)
Pearlite
-ferrite
Martensit
ic
Sphe
roidized
0.1 0.2 0.3 0.4
m/s
(b)
100
80
60
40
20
0
Toollife(min)
20 30 40 50 60 70 80 90
Cutting speed (ft/min)
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid 2008, Pearson EducationISBN No. 0-13-227271-7
Tool Wear
FIGURE 8.23 Relationship between crater-wear rate and average tool-chip interface
temperature in turning: (a) high-speed-steeltool; (b) C1 carbide; (c) C5 carbide. Note
that crater wear increases rapidly within anarrow range of temperature. Source: After
K.J. Trigger and B.T. Chao.
Average tool-chip interfacetemperature (F)
800 1200 1600 2000
0.15
0.3020
500 700 900 1100
10
0 0
C
mm
3/min
C
raterwearrate
(in
3/minx1
0-6)
a b c
Allowable Wear Land (mm)
Operation High-Speed Steels CarbidesTurning 1.5 0.4Face milling 1.5 0.4End milling 0.3 0.3Drilling 0.4 0.4Reaming 0.15 0.15
TABLE 8.5 Allowable average wear lands forcutting tools in various operations.
Rake face
Crater wear
Chip Flank face
FIGURE 8.23 Interface of chip (left) and rake
face of cutting tool (right) and crater wear incutting AISI 1004 steel at 3 m/s (585 ft/min).Discoloration of the tool indicates the
presence of high temperature (loss oftemper). Note how the crater-wear pattern
coincides with the discoloration pattern.Compare this pattern with the temperature
distribution shown in Fig. 8.16. Source:Courtesy of P.K. Wright.
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Acoustic Emission and Wear
FIGURE 8.25 Relationship between mean flank wear, maximum crater wear, and acoustic emission (noise generated
during cutting) as a function of machining time. This technique has been developed as a means for continuously and
indirectly monitoring wear rate in various cutting processes without interrupting the operation. Source: After M.S.Lan and D.A. Dornfeld.
Crater
wear
Flankw
ear
0.0050.0040.003
0.002
0.0010
in. mm
0.15
0.1
0.05
0Maximumc
raterdepth
Meanflankw
ear
1.5
1.0
0.5
0
mm in.
Mea
nRMS(mV)
0.0500.0400.0300.020
0.010
1500
1000
500
0
0 10 20 30 40 50 60
Elapsed machining time (min)
Roughness (Ra)
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Surface Finish
FIGURE 8.26 Range of surface roughnessesobtained in various machining processes. Note the
wide range within each group, especially in turningand boring. (See also Fig. 9.27).
Flame cutting
Snagging (coarse grinding)
Sawing
Planing, shaping
Drilling
Chemical machining
Electrical-discharge machining
Milling
Broaching
Reaming
Electron-beam machining
Laser machining
Electrochemical machining
Turning, boring
Barrel finishing
Electrochemical grinding
Roller burnishing
Grinding
Honing
Electropolishing
Polishing
Lapping
Superfinishing
Process 2000 1000 500 250 125 63 32 16 8 4 2 1 0.550 25 12.5 6.3 3.2 1.6 0.8 0.40 0.20 0.10 0.05 0.025 0.012
g ( )
in.m
Average application
Less frequent application
Sand casting
Die casting
Hot rolling
Forging
Permanent mold casting
Investment casting
Extruding
Cold rolling, drawing
Rough cutting
Casting
Forming
Machining
Advanced machining
Finishing processes
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Inclusions in Free-Machining Steels
FIGURE 8.29 Photomicrographs showing various types of inclusions in low-carbon, resulfurized free-machining steels. (a) Manganese-sulfide inclusions in AISI 1215 steel. (b) Manganese-sulfide inclusions and
glassy manganese-silicate-type oxide (dark) in AISI 1215 steel. (c) Manganese sulfide with lead particles as
tails in AISI 12L14 steel. Source: Courtesy of Ispat Inland Inc.
(a) (b) (c)
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Hardness of Cutting Tools
FIGURE 8.30 Hardness of various cutting-tool
materials as a function of temperature (hot hardness).The wide range in each group of tool materials results
from the variety of compositions and treatments
available for that group.
055
60
65
70
75
80
85
90
95 100 300 500 700
200 400 600 800 1000 1200 1400
20
25
30
35
40
45
50
55
60
65
70
Hardness(HRA)
HRC
Temperature (F)
C
Ceramics
Carbides
High-sp
eedsteels
Castalloys
C
arbon
too
lstee
ls
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Tool Materials
CarbidesCubic Single
High-Speed Cast Boron CrystalProperty Steel Alloys WC TiC Ceramics Nitride Diamond
Hardness 83-86 HRA 82-84 HRA 90-95 HRA 91-93 HRA 91-95 HRA 4000-5000 HK 7000-8000 HKCompressive strength
MPa 4100-4500 1500-2300 4100-5850 3100-3850 2750-4500 6900 6900psi 103 600-650 220-335 600-850 450-560 400-650 1000 1000
Transverse rupturestrength
MPa 2400-4800 1380-2050 1050-2600 1380-1900 345-950 700 1350psi 103 350-700 200-300 150-375 200-275 50-135 105-200
Impact strength
J 1.35-8 0.34-1.25 0.34-1.35 0.79-1.24 < 0.1 < 0.5 < 0.2in.-lb 12-70 3-11 3-12 7-11 < 1 < 5 < 2
Modulus of elasticityGPa 200 520-690 310-450 310-410 850 820-1050psi 106 30 75-100 45-65 45-60 125 120-150
Densitykg/m3 8600 8000-8700 10,000-15,000 5500-5800 4000-4500 3500 3500lb/in3 0.31 0.29-0.31 0.36-0.54 0.2-0.22 0.14-0.16 0.13 0.13
Volume of hardphase (%) 7-15 10-20 70-90 100 95 95
Melting or decom-
position temperatureC 1300 1400 1400 2000 1300 700F 2370 2550 2550 3600 2400 1300
Thermal conductivity,W/mK 30-50 42-125 17 29 13 500-2000
Coefficient of thermalexpansion, 106/C 12 4-6.5 7.5-9 6-8.5 4.8 1.5-4.8
The values for polycrystalline diamond are generally lower, except impact strength, which is higher.
TABLE 8.6 Typical range of properties of various tool materials.
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Properties of Tungsten-Carbide Tools
FIGURE 8.31 Effect of cobalt content in tungsten-carbide tools on mechanical properties. Notethat hardness is directly related to compressive strength (see Section 2.6.8) and hence, inversely
to wear [see Eq. (4.6)].
Wear(mg),compressiveandtransverse-
rupture
strength(kg/mm
2)
Cobalt content (% by weight)
Vickers
hardness(HV)
600
500
400
300
200
100
00 5 10 15 20 25 30
1750
1500
1250
1000
750
500
HRA 92.4
90.5
88.5
85.7
Com
pressivestrengthHardness
Wear
Transver
se-rupt
urestreng
th
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Inserts
FIGURE 8.32 Methods of mounting inserts on toolholders: (a) clamping, and (b) wing lockpins. (c)
Examples of inserts mounted using threadless lockpins, which are secured with side screws. Source:Courtesy of Valenite.
(c)(b)
Shank
Seat
Lockpin
Insert
(a)
Insert
Clamp
Clampscrew
Seator shim
Toolholder
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Insert Strength
FIGURE 8.33 Relative edge strength and tendency forchipping and breaking of inserts with various shapes.Strength refers to that of the cutting edge shown by the
included angles. Source: Courtesy of Kennametal, Inc.
90100 80 60 55 35
Increasing strength
Increased chipping and breaking
FIGURE 8.34 Edge preparations for inserts to improve edgestrength. Source: Courtesy of Kennametal, Inc.
Negative
withland
andhone
Negative
withland
Negative
honed
Negative
sharp
Positive
withhone
Positive
sharp
Increasing edge strength
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Historical Tool Improvement
FIGURE 8.35 Relative time required to machine with various cutting-tool materials, with
indication of the year the tool materials were introduced. Note that, within one century,machining time has been reduced by two orders of magnitude. Source: After Sandvik Coromant.
Carbon steel
High-speed steel
Cast cobalt-based alloys
Cemented carbides
Improved carbide grades
First coated gradesFirst double-coated grades
First triple-coated grades
1900 !10 !20 !30 !40 !50 !60 !70 !80 !90
100
26
15
6
3
1.5
10.7
M
achiningtime(min)
Year
!00
0.5 Functionally graded triple-coated
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Coated Tools
FIGURE 8.36 Wear patterns on high-speed-steel
uncoated and titanium-nitride-coated cuttingtools. Note that flank wear is lower for the
coated tool.
TiN coated
Uncoated
Flank wear
Rake
face
Tool
FIGURE 8.37 Multiphase coatings on a tungsten-carbide
substrate. Three alternating layers of aluminum oxide areseparated by very thin layers of titanium nitride. Inserts with as
many as 13 layers of coatings have been made. Coatingthicknesses are typically in the range of 2 to 10 m. Source:
Courtesy of Kennametal, Inc.
TiN
TiN
TiN
TiC + TiN
TiC + TiN
Carbide substrate
Al2O3
Al2O3
Al2O3
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Characteristics of MachiningCommercial tolerances
Process Characteristics (mm)
Turning Turning and facing operations are performed on all types of
materials; requires skilled labor; low production rate, butmedium to high rates can be achieved with turret lathes andautomatic machines, requiring less skilled labor.
Fine: 0.05-0.13
Rough: 0.13Skiving: 0.025-0.05
Boring Internal surfaces or profiles, with characteristics similar tothose produced by turning; stiffness of boring bar is impor-tant to avoid chatter.
0.025
Drilling Round holes of various sizes and depths; requires boring andreaming for improved accuracy; high production rate, laborskill required depends on hole location and accuracy specified.
0.075
Milling Variety of shapes involving contours, flat surfaces, and slots;
wide variety of tooling; versatile; low to medium productionrate; requires skilled labor.
0.13-0.25
Planing Flat surfaces and straight contour profiles on large surfaces;suitable for low-quantity production; labor skill required de-pends on part shape.
0.08-0.13
Shaping Flat surfaces and straight contour profiles on relatively smallworkpieces; suitable for low-quantity production; labor skillrequired depends on part shape.
0.05-0.13
Broaching External and internal flat surfaces, slots, and contours withgood surface finish; costly tooling; high production rate; laborskill required depends on part shape.
0.025-0.15
Sawing Straight and contour cuts on flats or structural shapes; notsuitable for hard materials unless the saw has carbide teethor is coated with diamond; low production rate; requires onlylow skilled labor.
0.8
TABLE 8.7 General characteristics of machining processes.
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Lathe Operations
FIGURE 8.40 Variety of machining operationsthat can be performed on a lathe.
Depth
of cut
ToolFeed, f
(a) Straight turning
(g) Cutting witha form tool
(e) Facing
(b) Taper turning (c) Profiling
(k) Threading
(d) Turning and
external grooving
(f) Face grooving
(h) Boring andinternal grooving
(i) Drilling
(j) Cutting off (l) Knurling
Workpiece
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Tool Angles
FIGURE 8.41 Designations andsymbols for a right-hand cutting tool.
The designation right hand meansthat the tool travels from right to left,
as shown in Fig. 8.19.
High-speed steel Carbide inserts
Material Back Side End Side Side and end Back Side End Side Side and end
rake rake relief relief cutting edge rake rake relief relief cutting edge
Aluminum and
magnesium alloys 20 15 12 10 5 0 5 5 5 15
Copper alloys 5 10 8 8 5 0 5 5 5 15
Steels 10 12 5 5 15 -5 -5 5 5 15
Stainless steels 5 8-10 5 5 15 -5-0 -5-5 5 5 15High-temperature 0 10 5 5 15 5 0 5 5 45
alloys
Refractory alloys 0 20 5 5 5 0 0 5 5 15
Titanium alloys 0 5 5 5 15 -5 -5 5 5 5
Cast irons 5 10 5 5 15 -5 -5 5 5 15
Thermoplastics 0 0 20-30 15-20 10 0 0 20-30 15-20 10
Thermosets 0 0 20-30 15-20 10 0 15 5 5 15
(a) End view (b) Side view
Shank
Flank face
Back rake
angle (BRA)
End reliefangle (ERA)
Wedgeangle
Side rake
angle (RA)
Side reliefangle (SRA)
(c) Top view
Rake face
End cutting-edgeangle (ECEA)
Side cutting-edgeangle (SCEA)
Noseangle
Noseradius
T A B L E 8 . 8 G e n e r a l
recommendations for tool anglesin turning.
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Turning Operations
FIGURE 8.42 (a) Schematic illustration of a turning operation, showing depth of cut, d, and feed, f. Cutting speedis the surface speed of the workpiece at the tool tip. (b) Forces acting on a cutting tool in turning. Fc is the
cutting force; Ft is the thrust or feed force (in the direction of feed); and Fr is the radial force that tends to pushthe tool away from the workpiece being machined. Compare this figure with Fig. 8.11 for a two-dimensional
cutting operation.
(a) (b)
d
DoDf
Workpiece
N
Chuck
Tool
Feed, f
ToolFeed, f
N
Fc
Ft Fr
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Cutting Speeds for Turning
FIGURE 8.43 The range of applicable cuttingspeeds and feeds for a variety of cutting-tool
materials.
Cubic boron nitride,diamond, andceramics
Cermets
Coatedcarbides
Uncoatedcarbides
3000
2000
1000
500
300
200
Cuttin
gspeed(ft/min)
0.004 0.008 0.012 0.020 0.030
Feed (in./rev)
0.10 0.20 0.30 0.50 0.75
mm/rev
900
600
300
150
100
50
m/min
Cutting SpeedWorkpiece Material m/min ft/minAluminum alloys 200-1000 650-3300Cast iron, gray 60-900 200-3000Copper alloys 50-700 160-2300High-temperature alloys 20-400 65-1300Steels 50-500 160-1600Stainless steels 50-300 160-1000Thermoplastics and thermosets 90-240 300-800Titanium alloys 10-100 30-330Tungsten alloys 60-150 200-500
Note: (a) The speeds given in this table are for carbides and ce-ramic cutting tools. Speeds for high-speed-steel tools are lowerthan indicated. The higher ranges are for coated carbides and cer-mets. Speeds for diamond tools are significantly higher than anyof the values indicated in the table.(b) Depths of cut, d, are generally in the range of 0.5-12 mm (0.02-0.5 in.).(c) Feeds, f, are generally in the range of 0.15-1 mm/rev (0.006-0.040 in./rev).
TABLE 8.9 Approximate Ranges of RecommendedCutting Speeds for Turning Operations
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Lathe
FIGURE 8.44 General view of a typical lathe, showing various major components. Source: Courtesy ofHeidenreich & Harbeck.
Spindle speedselector
Headstock assembly
Spindle (with chuck)
Tool post
Compoundrest
Cross slide
Carriage
Ways
Dead center
Tailstock quill
Tailstockassembly
Handwheel
BedFeed selector
Clutch
Chip pan
Apron
Split nut
Clutch
Longitudinal &transverse feedcontrol
Feed rod
Lead screw
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CNC Lathe
FIGURE 8.45 (a) A computer-numerical-control lathe, with two turrets; these machines have higher power and
spindle speed than other lathes in order to take advantage of advanced cutting tools with enhanced properties;(b) a typical turret equipped with ten cutting tools, some of which are powered.
DrillMultitooth
cutter
Tool forturning
or boring
Reamer
Individualmotors
Drill
Round turret forOD operationsCNC unit Chuck
End turret for ID operations Tailstock
(a) (b)
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Typical CNC Parts
FIGURE 8.46 Typical parts made on computer-numerical-control machine tools.
(a) Housing base
Material: Titanium alloyNumber of tools: 7Total machining time(two operations):5.25 minutes
Material: 52100 alloy steelNumber of tools: 4Total machining time(two operations):6.32 minutes
(c) Tube reducer
Material: 1020 Carbon SteelNumber of tools: 8Total machining time(two operations):5.41 minutes
(b) Inner bearing race
67.4 mm(2.654")
87.9 mm(3.462")
98.4 mm(3.876")
85.7 mm (3.375")32 threads per in.
235.6 mm(9.275")
78.5 mm
(3.092")
50.8 mm(2")
23.8 mm(0.938")
53.2 mm(2.094")
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Typical Production Rates
Operation Rate
Turning
Engine lathe Very low to low
Tracer lathe Low to medium
Turret lathe Low to medium
Computer-control lathe Low to medium
Single-spindle chuckers Medium to high
Multiple-spindle chuckers High to very high
Boring Very low
Drilling Low to medium
Milling Low to medium
Planing Very low
Gear cutting Low to medium
Broaching Medium to high
Sawing Very low to low
Note: Production rates indicated are relative: Very low is about
one or more parts per hour; medium is approximately 100 parts
per hour; very high is 1000 or more parts per hour.
TABLE 8.10 Typical production rates for various cutting operations.
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DrillsFIGURE 8.48 Two common types ofdrills: (a) Chisel-point drill. The function
of the pair of margins is to provide a
bearing surface for the drill againstwalls of the hole as it penetrates intothe workpiece. Drills with four margins
(double-margin) are available forimproved drill guidance and accuracy.
Drills with chip-breaker features arealso available. (b) Crankshaft drills.
These drills have good centering ability,and because chips tend to break up
easily, they are suitable for producingdeep holes.
(a) Chisel-point drill
Tang drive
Shankdiameter
Straightshank
Neck
Overall length
Flute length
Body
Point angle
Lip-reliefangle
Chisel-edgeangle
Chisel edge
Drilldiameter
Body diameterclearance
Clearancediameter
(b) Crankshaft-point drill
Lip
Margin
Land
Flutes Helix angle
Shank length
Web
Tang Taper shank
Drilling
Coredrilling
Stepdrilling
Counterboring
Countersinking
Reaming
Centerdrilling
Gundrilling
High-pressure
coolant
FIGURE 8.49 Various types of drills and drilling operations.
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Speeds and Feeds in Drilling
Surface Feed, mm/rev (in./rev) Spindle speed (rpm)Speed Drill Diameter Drill Diameter
Workpiece 1.5 mm 12.5 mm 1.5 mm 12.5 mmMaterial m/min ft/min (0.060 in.) (0.5 in.) (0.060 in.) (0.5 in.)Aluminum alloys 30-120 100-400 0.025 (0.001) 0.30 (0.012) 6400-25,000 800-3000Magnesium alloys 45-120 150-400 0.025 (0.001) 0.30 (0.012) 9600-25,000 1100-3000Copper alloys 15-60 50-200 0.025 (0.001) 0.25 (0.010) 3200-12,000 400-1500Steels 20-30 60-100 0.025 (0.001) 0.30 (0.012) 4300-6400 500-800Stainless steels 10-20 40-60 0.025 (0.001) 0.18 (0.007) 2100-4300 250-500
Titanium alloys 6-20 20-60 0.010 (0.0004) 0.15 (0.006) 1300-4300 150-500Cast irons 20-60 60-200 0.025 (0.001) 0.30 (0.012) 4300-12,000 500-1500Thermoplastics 30-60 100-200 0.025 (0.001) 0.13 (0.005) 6400-12,000 800-1500Thermosets 20-60 60-200 0.025 (0.001) 0.10 (0.004) 4300-12,000 500-1500
Note: As hole depth increases, speeds and feeds should be reduced. Selection of speeds andfeeds also depends on the specific surface finish required.
TABLE 8.11 General recommendations for speeds and feeds in drilling.
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Reamers and Taps
FIGURE 8.50 Terminology for a helical reamer.
Chamfer angleChamfer length
Chamfer relief
Helix angle, -
Primaryrelief angle
Margin
width
Land width
Radial rake
FIGURE 8.51 (a) Terminology for a tap;
(b) illustration of tapping of steel nuts inhigh production.
(b)
Rake angle
Hook angle
(a)
Tap
NutLand
Chamferrelief
Flute
Cutting edge
Heel
Chamferangle
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Typical Machined Parts
FIGURE 8.52 Typical parts and shapes produced by the machining processes
described in Section 8.10.
(a) (b) (c)
(d) (e) (f)
Drilled andtapped holes
Steppedcavity
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Face Milling
f
w
v
lc
lc
l
Workpiece
D
Cutter
(b)
f
v
(c)(a)
Insert
(d)
l
d
w
v
Machined surface
Workpiece
Cutter
FIGURE 8.54 Face-milling operationshowing (a) action of an insert in face
milling; (b) climb milling; (c) conventionalmilling; (d) dimensions in face milling.
Peripheral relief(radial relief)
Radialrake, 2
Axial rake, 1
End cutting-edge angle
Cornerangle
End relief(axial relief)
FIGURE 8.55 Terminology for a face-
milling cutter.
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Cutting Mechanics
Insert
Undeformed chip thickness
Depth of cut, d
Lead
angle
f
Feed per tooth, f
(a) (b)
FIGURE 8.56 The effect of lead angle on theundeformed chip thickness in face milling. Note that as
the lead angle increases, the undeformed chipthickness (and hence the thickness of the chip)
decreases, but the length of contact (and hence thewidth of the chip) increases. Note that the insert must
be sufficiently large to accommodate the increase incontact length.
(b)
Exit
Entry
Re-entry
Exit
(a)
Cutter
Workpiece
(c)
Cutter
Desirable
Milledsurface
+-
Undesirable
FIGURE 8.57 (a) Relativeposition of the cutter and the
insert as it first engages theworkpiece in face milling, (b)
insert positions at entry and exitnear the end of cut, and (c)
examples of exit angles of theinsert, showing desirable (positive
or negative angle) and undesirable(zero angle) positions. In all
figures, the cutter spindle is
perpendicular to the page.
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Milling Operations
(a) Straddle milling (b) Form milling
Arbor
(c) Slotting (d) Slitting
FIGURE 8.58 Cutters for (a) straddle
milling; (b) form milling; (c) slotting; and (d)slitting operations.
Cutting SpeedWorkpiece Material m/min ft/minAluminum alloys 300-3000 1000-10,000Cast iron, gray 90-1300 300-4200Copper alloys 90-1000 300-3300High-temperature alloys 30-550 100-1800Steels 60-450 200-1500Stainless steels 90-500 300-1600Thermoplastics and thermosets 90-1400 300-4500
Titanium alloys 40-150 130-500Note: (a) These speeds are for carbides, ceramic, cermets, and diamond cuttingtools. Speeds for high-speed-steel tools are lower than those indicated in this table.(b) Depths of cut, d, are generally in the range of 1-8 mm (0.04-0.3 in.).(c) Feeds per tooth, f, are generally in the range of 0.08-0.46 mm/rev (0.003-0.018in./rev).
TABLE 8.12 Approximate range of recommended cuttingspeeds for milling operations.
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Milling Machines
(a) (b)
Work
tableHead
Column
Base
Workpiece
Saddle
Knee
Overarm
Arbor
Column
Workpiece
Work table
Saddle
Knee
Base
T-slots T-slots
FIGURE 8.59 (a) Schematic illustration of a horizontal-spindle column-and-knee-type milling
machine. (b) Schematic illustration of a vertical-spindle column-and-knee-type milling machine.Source:After G. Boothroyd.
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Broaching
(a)
(b) (c)
FIGURE 8.60 (a) Typical parts finished by internal broaching. (b) Parts finished by surfacebroaching. The heavy lines indicate broached surfaces; (c) a vertical broaching machine. Source:
(a) and (b) Courtesy of General Broach and Engineering Company, (c) Courtesy of Ty Miles, Inc.
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Broaches
(b)
Root radius
Pitch
LandRake orhook angle
Toothdepth
Backoff or
clearance angle
(a)
Cut pertooth
Chip gullet
Workpiece
FIGURE 8.61 (a) Cutting action of a
broach, showing various features. (b)Terminology for a broach.
Pull end
Root diameter
Followerdiameter
Overall length
Shank length
Frontpilot
Rougheningteeth
Cutting teeth
Semifinishing teeth
Rear pilot
Finishingteeth
FIGURE 8.62 Terminology for a pull-type
internal broach, typically used for enlarginglong holes.
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Saws and Saw Teeth
(a) (b)
Straight tooth
Raker tooth
Wave tooth
Tooth set
Width
Back edge
Toothspacing
Tooth face
Tooth back(flank)
Tooth backclearance angle
Tooth rakeangle (positive)
Gulletdepth
FIGURE 8.63 (a) Terminology forsaw teeth. (b) Types of saw teeth,
staggered to provide clearance forthe saw blade to prevent binding
during sawing.
M2 HSS 64-66 HRC
Electron-beam weld
(a) (b)
Carbideinsert
Flexible alloy-steelbacking
FIGURE 8.64 (a) High-speed-steel teethwelded on a steel blade. (b) Carbide insertsbrazed to blade teeth.
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Machining Centers
Tools (cutters)
Index table
Tool storageTool-interchange arm
Traveling column
Spindle
Pallets
Bed
Spindle carrier
Computernumerical-control panel
FIGURE 8.67 Schematic illustration of a
computer numerical-controlled turning center.Note that the machine has two spindle headsand three turret heads, making the machine
tool very flexible in its capabilities. Source:Courtesy of Hitachi Seiki Co., Ltd.
1st Spindle head
2nd Turret head
1st Turret head
2nd Spindle head
3rd Turret head
FIGURE 8.66 A horizontal-spindle machining center,
equipped with an automatic tool changer. Tool magazinesin such machines can store as many as 200 cutting tools,
each with its own holder. Source: Courtesy of CincinnatiMachine.
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Reconfigurable Machining Center
(a) (b) (c)
FIGURE 8.69 Schematic illustration of assembly of different components of a
reconfigurable machining center. Source:After Y. Koren.
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Machining of Bearing Races
1. Finish turning ofoutside diameter
2. Boring and groovingon outside diameter
3. Internal groovingwith a radius-form tool
4. Finish boring of internalgroove and rough boringof internal diameter
5. Internal groovingwith form tooland chamfering
6. Cutting off finishedpart; inclined barpicks up bearing race
Tube
Bearingrace
Formtool
Form tool
FIGURE 8.70 Sequences involved in machining outer bearing races on a turning center.
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Hexapod
(a) (b)
Spindle
Hexapodlegs
Cutting tool
Workpiece
FIGURE 8.71 (a) A hexapod machine tool, showing its major components. (b) Closeup view of the cutting
tool and its head in a hexapod machining center. Source: National Institute of Standards and Technology.
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Chatter & Vibration
FIGURE 8.72 Chatter marks (rightof center of photograph) on the
surface of a turned part. Source:Courtesy of General Electric
Company.
1.2
0.8
0.4
0.0-0.4
-0.8
-1.2
-1.6
-2.00 1000 2000 3000 4000
10-5 s
10-
1V
Cast iron
(a)
1.2
0.8
0.4
0.020.4
20.8
21.2
21.6
22.00 1000 2000 3000 4000
10-5 s
10-
1V
Epoxy/graphite
(b)
FIGURE 8.73 Relative damping capacity of (a) gray cast iron and (b) epoxy-granitecomposite material. The vertical scale is the amplitude of vibration and the
horizontal scale is time.
Incre
asingdamping
Bedonly
Bed +carriage
Bed +headstock
Bed +carriage +headstock
Completemachine
FIGURE 8.74 Damping of vibrations as afunction of the number of components on alathe. Joints dissipate energy; thus, the greater the
number of joints, the higher the damping. Source:
After J. Peters.
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Machining EconomicsTotal cost
Machining cost
Nonproductive cost
Tool-change cost
Tool cost
(a)
Cos
tperpiece
Cutting speed
Machining time
Total time
Nonproductive timeTool-changing time
(b)
High-efficiency machining range
Cutting speed
Timeperpiece
FIGURE 8.75 Qualitative plots showing (a) cost per piece,and (b) time per piece in machining. Note that there is an
optimum cutting speed for both cost and time, respectively.The range between the two optimum speeds is known as the
high-efficiency machining range.
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Case Study: Ping Golf Putters
FIGURE 8.76 (a) The Ping Anser golf putter; (b) CAD model of rough machining of the putter outer surface; (c) rough machining
on a vertical machining center; (d) machining of the lettering in a vertical machining center; the operation was paused to take thephoto, as normally the cutting zone is flooded with a coolant; Source: Courtesy of Ping Golf, Inc.