common machining processes

7/31/2019 Common Machining Processes

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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian Schmid

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.

common machining processes

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