Fundamentals of Cutting - Manufacturing

7/29/2019 Fundamentals of Cutting - Manufacturing

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CHAPTER 8

Fundamentals of Cutting()

Material Removal: Machining Cutting

Abrasive processes: grinding

Nontraditional machining

Dimensional accuracyMaterial waste


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Factors Influencing Cutting ProcessesTABLE extra

Parameter Influence and interrelationship

Cutting speed, depth of cut,feed, cutting fluids Forces, power, temperature rise, tool life, type of chip, surface finish.

Tool angles As above; influence on chip flow direction; resistance to tool chipping.

Continuous chip Good surface finish; steady cutting forces; undesirable in automated

machinery.

Built-up edge chip Poor surface finish; thin stable edge can protect tool surfaces.

Discontinuous chip Desirable for ease of chip disposal; fluctuating cutting forces; can affectsurface finish and cause vibration and chatter.

Temperature rise Influences tool life, particularly crater wear, and dimensional accuracy of

workpiece; may cause thermal damage to workpiece surface.

Tool wear Influences surface finish, dimensional accuracy, temperature rise, forces and

power.Machinability Related to tool life, surface finish, forces and power.


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Mechanics of Chip Formation

Figure 8.3 (a) Schematic illustration of the basic mechanism of chip formation in metal cutting.(b) Velocity diagram in the cutting zone. See also section 8.2.5. Source: M. E. Merchant.

)cos(

sin,

==

c

o

t

trratiocutting

sincos)cos(

cs VVV ==

d

V

strainshears

=+= &);tan(cot,


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Chips and Their Photomicrographs

Figure 8.5 Basic types ofchips and theirphotomicrographsproduced in metal cutting:(a) continuous chip with

narrow, straight primaryshear zone; (b) secondaryshear zone at the chip-tool interface; (c)continuous chip withbuilt-up edge; (d)

continuous chip withlarge primary shear zone;(e) segmented ornonhomogeneous chipand (f) discontinuous

chip: impurities and hardparticles act as nucleationsires for cracks. Source:After M. C. Shaw, P. K.Wright, and S.Kalpakjian.

(f)

(b)(a) (c)

(d) (e)


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Built-Up Edge Chips

(b)

(c)

(a)

Figure 8.7 (a) Hardness distribution in the cutting zone for 3115 steel. Note that some regions inthe built-up edge are as much as three times harder than the bulk metal. (b) Surface finish in turning

5130 steel with a built-up edge. (c) Surface finish on 1018 steel in face milling. Magnifications:15X. Source: Courtesy of Metcut Research Associates, Inc.

Adhesion of workpiecematerial to rake face,and its growth

Geometry change

Surface finish

High hardness


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Chip Breakers

Figure 8.8 (a) Schematicillustration of the action of a chipbreaker. Note that the chipbreaker decreases the radius ofcurvature of the chip. (b) Chipbreaker clamped on the rake faceof a cutting tool. (c) Grooves incutting tools acting as chipbreakers. See also Fig. 8.39.

Long, continuous chips:entangled, interferingwith cutting operationsSafety hazard


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Examples of Chips Produced in Turning

Figure 8.9 Various chips produced in turning: (a) tightly curled chip; (b) chip hits workpiece andbreaks; (c) continuous chip moving away from workpiece; and (d) chip hits tool shank and breaks off.Source: G. Boothroyd, Fundamentals of Metal Machining and Machine Tools. Copyright 1975;

McGraw-Hill Publishing Company. Used with permission.

Change of tool geometry Control of chip flow Chip breakers

Interrupted cutting: milling No need of chip breakers


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Cutting With an Oblique Tool

Figure 8.10 (a) Schematic illustration of cutting with an oblique tool. (b) Top view showingthe inclination angle, i. (c) Types of chips produced with different inclination.

3-dimensional cutting 2-dimensional of orthogonal cutting

)sincos(sinsin:221

neciianglerakeeffectivei +=


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Right-Hand Cutting Tool

Figure 8.11 (a) Schematic illustration of a right-hand cutting tool. Although these tools have

traditionally been produced from solid tool-steel bars, they have been largely replaced bycarbide or other inserts of various shapes and sizes, as shown in (b). The various angles onthese tools and their effects on machining in section 8.8.2.

Various angles: should be selected properly


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Forces in Two-Dimensional Cutting

Figure 8.12 Forces acting on a cutting tool intwo-dimensional cutting. Note that theresultant force,R, must be collinear tobalance the forces.

Fc: cutting force, Ft: thrust forceF: friction force, N: normal force

R: resultant force

Fs: shear force, Fn: normal force

cos,sin RNRF ==

tan

tan

tantc

ct

FF

FF

N

F

tcoefficienfriction

+

===)tan(),sin( == ctt FFRF

sin:,:

o

ss

n

s

s wt

AA

F

stressnormalA

F

stressshear ===


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Approximate Energy Requirements in Cutting

OperationsTABLE extra Approximate Energy Requirements in

Cutting Operations (at drive motor,

corrected for 80% efficiency; multiply by

1.25 for dull tools).

Specific energy

Material W-s/mm3

hp-min/in.3

Aluminum alloys

Cast irons

Copper alloys

High-temperature alloys

Magnesium alloys

Nickel alloysRefractory alloys

Stainless steels

Steels

Titanium alloys

0.41.1

1.65.5

1.43.3

3.38.5

0.40.6

4.96.83.89.6

3.05.2

2.79.3

3.04.1

0.150.4

0.62.0

0.51.2

1.23.1

0.150.2

1.82.51.13.5

1.11.9

1.03.4

1.11.5


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Temperature Distribution and Heat Generated

Figure 8.19 Typical temperature distribution thecutting zone. Note the steep temperature gradientswithin the tool and the chip. Source: G. Vieregge.

375.0,5.0:

125.0,2.0:

:

2.1

:

3

==

==

=

batoolHSS

batoolCarbide

fVTturninginetemperaturmean

K

Vt

c

YT

cuttingorthogonalinetemperaturmean

ba

of


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Temperature Distributions

Figure 8.21 Temperatures developed n turning 52100 steel: (a) flank temperature distribution; and(b) tool-chip interface temperature distribution. Source: B. T. Chao and K. J. Trigger.


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Typical Energy Distibution vs. Cutting Speed

Figure 8.22 Percentage of the heat generated incutting going into the workpiece, tool, and chip,

as a function of cutting speed. Note that the chipcarries away most of the heat.

Increase of cutting speed short time for the heat to bedissipated more heat in chip


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Examples of Wear and Tool Failures

Figure 8.24 (a) Schematic illustrations oftypes of wear observed on various typesof cutting tools. (b) Schematicillustrations of catastrophic tool failures.A study of the types and mechanisms of

tool wear and failure is essential to thedevelopment of better tool materials.

Forces, temperature, sliding

Tool wear

Surface quality, economics

Chipping: breaking awayTool condition monitoring

Direct: toolmakers microscope

Indirect: acoustic emission


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Flank and Crater Wear

(e)(d)

(a) (b) (c)

Figure 8.25 (a) Flankand crater wear in acutting tool. Toolmoves to the left. (b)

View of the rake faceof a turning tool,showing nose radiusR and crater wearpattern on the rakeface of the tool. (c)View of the flankface of a turning tool,showing the averageflank wear land VBand the depth-of-cutline (wear notch).See also Fig. 8.24.

(d) Crater and (e)flank wear on acarbide tool. Source:J.C. Keefe, LehighUniversity.


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Tool Life

Figure 8.26 Effect of workpiece microstructure and hardness on tool life in turning ductile cast iron.Note the rapid decrease in tool life as the cutting speed increases. Tool materials have been developedthat resist high temperatures such as carbides, ceramics, and cubic boron nitride, as described in

Chapter 21.

Figure 8.27 Tool-life curves for a variety of cutting-toolmaterials. The negative inverse of the slope of these curves is the

exponent n in the Taylor tool-life equations and Cis the cuttingspeed at T= 1 min.

CVTn =F.W.Taylor:

Modified tool life: CfdVTyxn =

417711

= fdVCfdVCTnynxnn

Flank wear


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Tool Wear

TABLE 8.5 Range ofn Values for VariousTool Materials

High-speed steelsCast alloysCarbides

Ceramics

0.080.20.10.150.20.5

0.50.7

TABLE 8.6 Allowable Average Wear Land (VB) forCutting Tools in Various Operations

Allowable wear land (mm)Operation High-speed Steels Carbides

Turning

Face millingEnd milling

DrillingReaming

1.5

1.50.3

0.40.15

0.4

0.40.3

0.40.15

Note: 1 mm = 0.040 in.

Recommended cutting speed: V that gives a tool life of 60-120 min for HSS tool,

and 30-60 min for carbide tools


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Crater Wear

Figure 8.29 Relationship between crater-wear rateand average tool-chip interface temperature: (a) High-speed steel; (b) C-1 carbide; and (c) C-5 carbide.Note how rapidly crater-wear rate increases as thetemperature increases. Source: B. T. Chao and K. J.Trigger.

Figure 8.30 Cutting tool (right) and chip (left) interfacein cutting plain-carbon steel. The discoloration of thetool indicates the presence of high temperatures.Compare this figure with Fig. 8.19. Source: P. K.Wright.

Location of maximum temperature

location of maximum crater wear

S f fi i h d i i


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Surface Roughnesses

Figure 8.33 The rangeof surface roughnessobtained in various

machining processes.Note the wide rangewithin each group,especially in turningand boring. See also

Fig. 9.31.

Surface finish and integrity

- finish: geometry

- integrity: fatigue,

corrosion,


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Surfaces Produced by Cutting

Figure 8.34 Surfaces produced on steel by cutting, as observed with a scanning electron microscope:(a) turned surface and (b) surface produced by shaping. Source: J. T. Black and S. Ramalingam.

(b)(a)

BUE: surface damage

Ceramic and diamond tools: less BUE better surface finish


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Dull Tool in Orthogonal Cutting and Feed Marks

Figure 8.35 Schematic illustration of a dull tool inorthogonal cutting (exaggerated). Note that at smalldepths of cut, the positive rake angle can effectivelybecome negative, and the tool may simply ride overand burnish the workpiece surface.

Figure 20.23 Schematic illustration of feed marks in

turning (highly exaggerated). See also Fig. 20.2.

Small depth of cut : negative rake angle

Rubbing: heat residual stresses

Higher f, smaller R larger feed marks


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Cutting-Tool Materials and Cutting

Fluids

VIDEO


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Cutting Tool Material Hardnesses

Figure 8.37 The hardness of variouscutting-tool materials as a function oftemperature (hot hardness). The widerange in each group of materials is due to

the variety of tool compositions andtreatments available for that group. Seealso Table 21.1 for melting ordecomposition temperatures of thesematerials.

Required characteristics

Hardness at elevated temp.Toughness: interrupted cutting

Wear resistance

Chemical stability or inertness


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Typical Properties of Tool Materials

Table 8.7

Carbides

PropertyHigh-speed

steels Cast alloys WC TiC Ceramics

Cubic boron

nitrideSingle-crystal

diamond*

Hardness 83 86 HRA 82 84 HRA 90 95 HRA 91 93 HRA 91 95 HRA 4000 5000 HK 7000 8000 HK46 62 HRC 1800 2400 HK 1800 3200 HK 2000 3000 HK

Compressive strength

MPa

psi x103

4100 4500600 650

1500 2300220 335

4100 5850600 850

3100 3850450 560

2750 4500400 650

69001000

69001000

Transverse rupture strengthMPa

psi x103

2400 4800350 700

1380 2050200 300

1050 2600150 375

1380 1900200 275

345 95050 135

700105

1350200

Impact strengthJ

in.- lb

1.35 8

12 70

0.34 1.25

3 11

0.34 1.35

3 12

0.79 1.24

7 11

< 0.1

< 1

< 0.5

< 5

< 0.2

< 2

Modulus of elasticityGPa

psi x106

20030

520 69075 100

310 45045 65

310 41045 60

850125

820 1050120 150

Density

kg/m3

lb/in.3

86000.31

8000 87000.29 0.31

10,000 15,0000.36 0.54

5500 58000.2 0.22

4000 45000.14 0.16

35000.13

35000.13

Volume of hard phase, % 7 15 10 20 70 90 100 95 95

Melting or decomposition

temperatureCF

13002370

14002550

14002550

20003600

13002400

7001300

Thermal conductivity, W/m K

30 50 42 125 17 29 13 500 2000

Coefficient of thermal

expansion, x106

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.

G l Ch i i f C i T l M i l


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General Characteristics of Cutting-Tool Materials

TABLE 8.8 General Characteristics of Cutting- Tool Materials. These Tool Materials Have a Wide Range of

Compositions and Properties; Thus Overlapping Characteristics Exist in Many Categories of Tool Materials.Carbon andlow- to

medium- alloy

steels

High speed

steels

Cast- cobalt

alloys

Uncoated

carbides

Coated

carbides Ceramics

Polycrystalline

cubic boron

nitride Diamond

Hot hardness Increasing

Toughness IncreasingImpact strength Increasing

Wear resistance IncreasingChipping

resistance

Increasing

Cutting speed IncreasingThermal-shock

resistance

Increasing

Tool material cost Increasing

Depth of cut Light to

medium

Light to

heavy

Light to

heavy

Light to

heavy

Light to

heavy

Light to

heavy

Light to heavy Very light for

single crystaldiamond

Finish obtainable Rough Rough Rough Good Good Very good Very good Excellent

Method ofprocessing

Wrought Wrought,

cast, HIP*

sintering

Cast andHIP

sintering

Coldpressing

and

sintering

CVD or

PVD

Coldpressing

and

sintering

or HIPsintering

High-pressure,high-temperature

sintering

High-pressure,high-temperature

sintering

Fabrication Machining

and grinding

Machining

and

grinding

Grinding Grinding Grinding Grinding and

polishing

Grinding and

polishing

Source : R. Komanduri, Kirk- Othmer Encyclopedia of Chemical Technology , (3d ed.). New York: Wiley, 1978.* Hot- isostatic pressing.

Chemical- vapor deposition, physical- vapor deposition.

Operating Characteristics of Cutting Tool Materials


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Operating Characteristics of Cutting-Tool Materials

TABLE extra

Tool materials General characteristics Modes of tool wear orfailure LimitationsHigh-speed steels High toughness, resistance

to fracture, wide range of

roughing and finishingcuts, good for interrupted

cuts

Flank wear, crater wear Low hot hardness, limitedhardenability, and limited

wear resistance

Uncoated carbides High hardness over a widerange of temperatures,

toughness, wear resistance,versatile and wide range of

applications

Flank wear, crater wear Cannot use at low speedbecause of cold welding of

chips and microchipping

Coated carbides Improved wear resistanceover uncoated carbides,better frictional andthermal properties

Flank wear, crater wear Cannot use at low speedbecause of cold welding ofchips and microchipping

Ceramics High hardness at elevatedtemperatures, high abrasive

wear resistance

Depth-of-cut line notching,microchipping, gross

fracture

Low strength, low thermo-mechanical fatigue strength

Polycrystalline cubic

boron nitride (cBN)

High hot hardness,

toughness, cutting-edgestrength

Depth-of-cut line notching,

chipping, oxidation,graphitization

Low strength, low

chemical stability at highertemperature

Polycrystalline diamond Hardness and toughness,abrasive wear resistance

Chipping, oxidation,graphitization

Low strength, lowchemical stability at higher

temperatureSource: After R. Komanduri and other sources.

C b d di ll l


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Carbide Inserts

Figure 8.39 Typical carbide inserts with variousshapes and chip-breaker features; round inserts arealso available (Fig. 8.6). The holes in the inserts arestandardized for interchangeability. Source:

Courtesy of Kyocera Engineered Ceramics, Inc., andManufacturing Engineering Magazine, Society ofManufacturing Engineers.

Carbon and medium-alloy steels

High-speed steels

Cast-cobalt alloys

High hardness over wide rangeof temperature

Low thermal expansion

High elastic modulus

High thermal conductivity

Tungsten carbide (WC)

Titanium carbide (TiC)

Figure 8.40 Examples of inserts attached to toolholders with threadless lockpins, which are securedwith side screws. Source: Courtesy of Valenite.


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Edge Strength

Figure 8.41 Relativeedge strength andtendency for chippingand breaking of insets

with various shapes.Strength refers to thecutting edge shown bythe included angles.Source: Kennametal, Inc.

Figure 8.42 Edge preparation ofinserts to improve edge strength.See also Section 23.2. Source:Kennametal, Inc.


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Classification of Tungsten Carbides

Table 8.9 Classification of Tungsten Carbide According to Machining Applications. See also Chapters 22 and 23 for Cutting ToolRecommendations

Characteristics ofISO Standard ANSIClassification

Number

Materials to bemachined

MachiningOperation

Type of carbide

Cut Carbide

K30-K40 C-1 Roughing

K20 C-2 General purpose

K10 C-3 Light finishing

K01 C-4

Cast iron,nonferrous metals

and nonmetallicmaterials requiringabrasion resistance

Precisionmachining

Wear-resistantgrades; generally

straight WC-Cowith varyinggrain sizes

Increasing Cuttingspeed

Increasing Feedrate

Increasinghardness and wear

resistance

Increasingstrength and

binder content

P30-P50 C-5 Roughing

P20 C-6 General purpose

P10 C-7 Light purpose

P01 C-8

Steels and steelalloys requiringcrater and

deformation

resistance

Precision finishing

Crater-resistantgrades; variousWC-Co

compositions

with TiC and/orTaC alloys

Increasing Cuttingspeed

Increasing Feed

rate

Increasinghardness and wear

resistance

Increasing

strength andbinder content

Note: The ISO and ANSI comparisons are approximate.


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ISO Classification of Carbide Cutting ToolsAccording to Use

TABLE 8.10

Symbol Workpiece material Color code

Designation in increasing orderof wear resistance and

decreasing order of toughness in

each category, in increments of 5

P Ferrous metals with long chips Blue P01, P05 through P50M Ferrous metals with long or short

chips; nonferrous metals

Yellow M10 through M40

K Ferrous metals with short chips;

nonferrous metals; nonmetallicmaterials

Red K01, K10 through K40


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Effect of Coating Materials

Figure 8.43 Relative time required tomachine with various cutting-tool materials,indicating the year the tool materials were

introduced. Source: Sandvik Coromant.

Coating material:

TiN, TiC, Al2O3Diamond

New: TiCN, TiAlN, CrC, ZrN,

Thickness: 2-10 m

Coating method: CVD, PVD,

Multiphase Coatings


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Multiphase Coatings

Figure 8.45 Multiphase coatings on a tungsten-carbide substrate. Three alternating

layers of aluminum oxide are separated by very thin layers ot titanium nitride. Insertswith as many as thirteen layers of coatings have been made. Coating thicknesses aretypically in the range of 2 to 10 m. Source: Courtesy of Kennametal, Inc., andManufacturing Engineering Magazine, Society of Manufacturing Engineers.


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Properties for Groups of Tool Materials

Figure 8.46 Ranges of properties forvarious groups of tool materials. Seealso Tables 21.1 through 21.5.

Cubic Boron Nitride


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Cubic Boron Nitride

Figure 8.47 Construction of a polycrystalline cubicboron nitride or a diamond layer on a tungsten-carbideinsert.

Figure 8.48 Inserts with polycrystallinecubic boron nitride tips (top row) and solidpolycrystalline CBN inserts (bottom row).

Source: Courtesy of Valenite.


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Approximate Cost of Selected Cutting Tools

TABLE extra

Tool Size (in.) Cost ($)High-speed steel tool bits 1/4 sq.x 2 1/2 long 12

1/2 sq. x 4 37Carbide-tipped (brazed) tools for turning 1/4 sq. 2

3/4 sq. 4

Carbide inserts, square 3/16"thick

Plain 1/2 inscribed circle 59

Coated 610Ceramic inserts, square 1/2 inscribed circle 812

Cubic boron nitride inserts, square 1/2 inscribed circle 6090

Diamond-coated inserts 1/2 inscribed circle 5060

Diamond-tipped inserts (polycrystalline) 1/2 inscribed circle 90100


38/135

Machining Processes Used to Produce

Round Shapes

VIDEO

Cutting Operations


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Cutting Operations

Figure 8.51 Variouscutting operationsthat can be performedon a late. Not that allparts have circularsymmetry.

Cutting speeds:0.15-4 m/s

Roughing cuts:to>0.5 mm,

f=0.2-2 mm/rev.Finishing cuts:

lower depth ofcuts and feeds

General Characteristics of Machining


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General Characteristics of MachiningProcesses

TABLE extra General Characteristics of Machining Processes Described in Chapters 22 and 23

Process Characteristics Commercial tolerances(mm)

Turning Turning and facing operations on all types of materials; uses single-point or form tools; requires skilled

labor; low production rate, but medium to high with turret lathes and automatic machines, requiring less-

skilled labor.

Fine: 0.050.13

Rough: 0.13

Skiving: 0.0250.05

Boring Internal surfaces or profiles, with characteristics similar to turning; stiffness of boring bar important to avoidchatter. 0.025

Drilling Round holes of various sizes and depths; requires boring and reaming for improved accuracy; high

production rate; labor skill 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 production rate; requires skilled labor.

0.130.25

Planing Flat surfaces and straight contour profiles on large surfaces; suitable for low-quantity production; labor skill

required depends on part shape.

0.080.13

Shaping Flat surfaces and straight contour profiles on relatively small workpieces; suitable for low-quantityproduction; labor skill required depends on part shape. 0.050.13

Broaching External and internal flat surfaces, slots, and contours with good surface finish; costly tooling; high

production rate; labor skill required depends on part shape.

0.0250.15

Sawing Straight and contour cuts on flat or structural shapes; not suitable for hard materials unless saw has carbide

teeth or is coated with diamond; low production rate; requires only low labor skill.

0.8

Right-Hand


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Right HandCutting Tool

Figure 8.52 (a) Designations andsymbols for a right-hand cutting tool;solid high-speed-steel tools have asimilar designation. Right-handmeans that the tool travels from rightto left as shown in Fig. 8.51a.(continued)

Rake angle: chip flow, strengthof tool tip side vs back

Relief angle: interference andrubbing at the tool-workpieceinterface

Cutting edge angle: chipformation, tool strength, cutting

forcesNose radius: surface finish, tool-

tip strength


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Right-Hand Cutting Tool (cont.)

Figure 8.52 (continued) (b) Square insert in a right-hand toolholder for a turningoperation. A wide variety of toolholders are available for holding inserts atvarious angles. Source: Kennametal Inc.


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Schematic Illustration of a Turning Operation

Figure 8.53 (a) Schematic illustration of a turning operation showing depth of cut, d, and feed,f.Cutting speed is the surface speed of the workpiece at the tool tip. (b) Forces acting on a cutting toolin turning. Fc, is the cutting force, Ft is the thrust or feed force (in the direction of feed, Fr is the

radial force that tends to push the tool away from the workpiece being machined. Compare thisfigure with Fig. 8.12 for a two-dimensional cutting operation.

dfNDMRRrateremovalmarerial avg=,

General Recommendations for Turning Tool


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General Recommendations for Turning ToolAngles

TABLE 8.11

High-speed steel Carbide (inserts)

Material Back rake Side rake End relief Side relief

Side andend

cutting

edge

Back

rake

Side

rake End relief Side relief

Side andend

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 5 810 5 5 15 50 55 5 5 15High-temperature

alloys

0 10 5 5 15 5 0 5 5 45

Refractory alloys 0 20 5 5 5 0 0 5 5 15

Titanium alloys 0 5 5 5 15 5 5 55 5

Cast irons 5 10 5 5 15 5 5 5515Thermoplastics 0 0 2030 1520 10 0 0 2030 1520 10

Thermosets 0 0 2030 1520 10 0 15 5 5 15

Summary of Turning Parameters andF l


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Formulas

TABLE 8.14N = Rotational speed of the workpiece, rpmf = Feed, mm/rev or in/rev

v = Feed rate, or linear speed of the tool along workpiece length, mm/min or in/min=fN

V = Surface speed of workpiece, m/min or ft/min

= Do N(for maximum speed)= DavgN(for average speed)

l = Length of cut, mm or in.

Do = Original diameter of workpiece, mm or in.Df = Final diameter of workpiece, mm or in.

Davg = Average diameter of workpiece, mm or in.

= (Do +Df) /2d = Depth of cut, mm or in.

= (Do +Df) /2t = Cutting time, s or min

=l/f N

MRR = mm3/min or in

3/min

= DavgdfN

Torque = Nm or lb ft

= ( Fc )(Davg/2 )Power = kW or hp

= (Torque) (w) , where w=2p radians/min

Note: The units given are those that are commonly used; however, appropriate units must beused and checked in the formulas.

Cutting Speeds for Various Tool Materials


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Cutting Speeds for Various Tool Materials

Figure 8.54 The range of applicablecutting speeds and feeds for a variety oftool materials. Source: Valenite.

Components of a Lathe


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C p s a a

Figure 8.55Components of alathe. Source:Courtesy ofHeidenreich &

Harbeck

VIDEO

General Recommendations for TurningO


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OperationsTABLE extra

General-purpose starting conditions Range for roughing and finishing

Workpiece material Cutting tool

Depth of cut

mm (in.)

Feed

mm/rev

(in./rev)

Cutting speed

m/min

(ft/min)

Depth of cut

mm

(in.)

Feed

mm/rev

(in./rev)

Cutting speed

m/min

(ft/min)

Low-C and free-

machining steels

Uncoated

carbide

1.5-6.3

(0.06-0.25)

0.35

(0.014)

90

(300)

0.5-7.6

(0.02-0.30)

0.15-1.1

(0.006-0.045)

60-135

(200-450)

Ceramic-coatedcarbide

" " 245-275(800-900)

" " 120-425(400-1400)

Triple coated

carbide

" " 185-200

(600-650)

" " 90-245

(300-800)

TiN-coated

carbide

" " 105-150

(350-500)

" " 60-230

(200-750)

Al2O3 ceramic " 0.25

(0.010)

395-440

(1300-1450)

" " 365-550

(1200-1800)

Cermet " 0.30(0.012)

215-290(700-950)

" " 105-455(350-1800)

Medium and high-C

steels

Uncoated

carbide

1.2-4.0

(0.05-0.20)

0.30

(0.012)

75

(250)

2.5-7.6

(0.10-0.30)

0.15-0.75

(0.006-0.03)

45-120

(150-400)

Ceramic-coated

carbide

" " 185-230

(600-750)

" " 120-410

(400-1350)

Triple coated

carbide

" " 120-150

(400-500)

" " 75-215

(250-700)

TiN-coatedcarbide

" " 90-200(300-650)

" " 45-215(150-700)


(0.010)

335

(1100)

" " 245-455

(800-1500)

Cermet " 0.25

(0.010)

170-245

(550-800)

" " 105-305

(350-1000)

General Recommendations for Turning Operations (cont.)


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TABLE extra (continued)General-purpose starting conditions Range for roughing and finishing

Workpiece

material Cutting tool

Depth of cut

mm (in.)

Feed

mm/rev

(in./rev)

Cutting speed

m/min

(ft/min)

Depth of cut

mm

(in.)

Feed

mm/rev

(in./rev)

Cutting speed

m/min

(ft/min)

Cast iron, gray Uncoatedcarbide

1.25-6.3(0.05-0.25)

0.32(0.013)

90(300)

0.4-12.7(0.015-0.5)

0.1-0.75(0.004-0.03)

75-185(250-600)

Ceramic-coated

carbide

" " 200

(650)

" " 120-365

(400-1200)

TiN-coatedcarbide

" " 90-135(300-450)

" " 60-215(200-700)


(0.010)

455-490

(1500-1600)

" " 365-855

(1200-2800)SiN ceramic " 0.32

(0.013)

730

(2400)

" " 200-990

(650-3250)

Stainless steel,

austenitic

Triple coated

carbide

1.5-4.4

(0.06-0.175)

0.35

(0.014)

150

(500)

0.5-12.7

(0.02-0.5)

0.08-0.75

(0.003-0.03)

75-230

(250-750)TiN-coated

carbide

" " 85-160

(275-525)

" " 55-200

(175-650)

Cermet " 0.30(0.012)

185-215(600-700)

" " 105-290(350-950)

High-temperature

alloys, nickel base

Uncoated

carbide

2.5

(0.10)

0.15

(0.006)

25-45

(75-150)

0.25-6.3

(0.01-0.25)

0.1-0.3

(0.004-0.012)

15-30

(50-100)

Ceramic-coated

carbide

" " 45

(150)

" " 20-60

(65-200)TiN-coated

carbide

" " 30-55

(95-175)

" " 20-85

(60-275)Al2O3 ceramic " " 260

(850)

" " 185-395

(600-1300)

SiN ceramic " " 215

(700)

" " 90-215

(300-700)Polycrystalline

CBN

" " 150

(500)

" " 120-185

(400-600)

General Recommendations for Turning Operations(cont.)


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TABLE extra (continued)General-purpose starting conditions Range for roughing and finishing

Workpiecematerial Cutting tool

Depth of cutmm (in.)

Feedmm/rev(in./rev)

Cutting speedm/min(ft/min)

Depth of cutmm(in.)

Feedmm/rev(in./rev)

Cutting speedm/min(ft/min)

Titanium alloys Uncoatedcarbide

1.0-3.8(0.04-0.15)

0.15(0.006)

35-60(120-200)

0.25-6.3(0.01-0.25)

0.1-0.4(0.004-0.015)

10-75(30-250)

TiN-coatedcarbide

" " 30-60(100-200)

" " 10-100(30-325)

Aluminum alloys,free machining Uncoated

carbide

1.5-5.0

(0.06-0.20)

0.45

(0.018)

490

(1600)

0.25-8.8

(0.01-0.35)

0.08-0.62

(0.003-0.025)

200-670

(650-2000)TiN-coated

carbide

" " 550

(1800)

" " 60-915

(200-3000)

Cermet " " 490

(1600)

" " 215-795

(700-2600)

Polycrystallinediamond

" " 760(2500)

" " 305-3050(1000-10,000)

High silicon Polycrystalline

diamond

" " 530

(1700)

" " 365-915

(1200-3000)Copper alloys Uncoated

carbide

1.5-5.0

(0.06-0.20)

0.25

(0.010)

260

(850)

0.4-7.51

(0.015-0.3)

0.15-0.75

(0.006-0.03)

105-535

(350-1750)Ceramic-coated

carbide

" " 365

(1200)

" " 215-670

(700-2200)Triple-coated

carbide

" " 215

(700)

" " 90-305

(300-1000)TiN-coated

carbide

" " 90-275

(300-900)

" " 45-455

(150-1500)Cermet " " 245-425

(800-1400)

" " 200-610

(650-2000)Polycrystallinediamond

" " 520(1700)

" " 275-915(900-3000)

General Recommendations for Turning


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gOperations (cont.)

General-purpose starting conditions Range for roughing and finishing

Workpiece

material Cutting tool

Depth of cut

mm (in.)

Feed

mm/rev

(in./rev)

Cutting speed

m/min

(ft/min)

Depth of cut

mm

(in.)

Feed

mm/rev

(in./rev)

Cutting speed

m/min

(ft/min)

Tungsten alloys Uncoatedcarbide

2.5(0.10)

0.2(0.008)

75(250)

0.25-5.0(0.01-0.2)

0.12-0.45(0.005-0.018)

55-120(175-400)

TiN-coated

carbide

" " 85

(275)

" " 60-150

(200-500)

Thermoplastics and

thermosets

TiN-coated

carbide

1.2

(0.05)

0.12

(0.005)

170

(550)

0.12-5.0

(0.005-0.20)

0.08-0.35

(0.003-0.015)

90-230


diamond

" " 395

(1300)

" " 150-730

(500-2400)

Composites,

graphite reinforced

TiN-coated

carbide

1.9

(0.075)

0.2

(0.008)

200

(650)

0.12-6.3

(0.005-0.25)

0.12-1.5

(0.005-0.06)

105-290


diamond

" " 760

(2500)

" " 550-1310

(1800-4300)

Source: Based on data from Kennametal, Inc.Note: Cutting speeds for high-speed steel tools are about one-half those for uncoated

carbides.

General Recommendations for Cutting Fluids forMachining


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Machining

TABLE 8.13Material Type of fluid

Aluminum

Beryllium

CopperMagnesium

Nickel

Refractory

Steels (carbon and low alloy)

Steels (stainless)

TitaniumZinc

Zirconium

D, MO, E, MO FO, CSN

MC, E, CSN

D, E, CSN, MO FOD, MO, MO FO

MC, E, CSN

MC, E, EP

D, MO, E, CSN, EP

D, MO, E, CSN

CSN, EP, MOC, MC, E, CSN

D, E, CSN

Note: CSN, chemicals and synthetics; D, dry; E, emulsion; EP,extreme pressure; FO, fatty oil; and MO, mineral oil.

Reduction of friction,wear improving toollife and surface finish

Reduction of forces andenergy consumption

Low temperature anddistortion

Wash away the chipsProtection of machinedsurfaces fromenvironmental corrosion

Typical Capacities and Maximum Workpiece


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yp p pDimensions for Machine Tools

TABLE extra

Machine tool Maximum dimension (m) Power (kW)

Maximumrpm

Lathes (swing/length)

Bench 0.3/1


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Figure extra (a) and (b) Schematic illustrations of a draw-in type collet. The workpiece is placed

in the collet hole, and the conical surfaces of the collet are forced inward by pulling it with a drawbar into the sleeve. (c) A push-out type collet. (d) Workholding of a part on a face plate.

Mandrels


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Mandrels

Figure extra Various types of mandrels to hold workpieces for turning. These mandrels are usuallymounted between centers on a lathe. Note that in (a), both the cylindrical and the end faces of theworkpiece can be machined, whereas in (b) and (c), only the cylindrical surfaces can be machined.

Turret Lathe VIDEO


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Figure extra Schematicillustration of thecomponents of a turretlathe. Note the twoturrets: square andhexagonal (main). Source:

American Machinist andAutomated Manufacturing.

Examples of TurretsVIDEO(horizontalturret lathe)

VIDEO(vertical turretlathe)


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(a) (b)

Figure extra (a) A turret with six different tools for inside-diameter and outside-diameter cutting and threading operations. (b) A turret with eight different cutting

tools. Source: Monarch Machine Tool Company.

turret lathe) lathe)

Computer Numerical Control Lathe


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p

Figure 8.56 A computer numerical control lathe. Note the twoturrets on this machine. Source: Jones & Lamson, Textron, Inc.

VIDEO

Examples of Parts Made on CNC TurningMachine Tools


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Machine Tools

Figure 8.57

Machining of Various Complex Shapes


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TABLE extra Example: Machining of Various Complex Shapes

Operation Cutting speed Depth of cut Feed Tool

(a)

OD

roughing 1150 rpm

160 m/min

(525 fpm)

3 mm (0.12 in.) 0.3 mm/rev

(0.012 ipr) K10 (C3)

ODfinishing 1750 250(820) 0.2(0.008) 0.15(0.0059) K10 (C3)

Lead

roughing 300

45

(148)

3

(0.12)

0.15

(0.0059) K10 (C3)

Lead

finishing 300

45

(148)

0.1

(0.004)

0.15

(0.0059)

Diamond

compact(b)

Eccentricroughing 200 rpm

5-11 m/min(16-136 fpm)

1.5 mm(0.059 in)

0.2 mm/rev(0.008 ipr) K10 (C3)

Eccentric

finishing 200

5-11

(16-36)

0.1

(0.004)

0.05

(0.0020) K10 (C3)

(c)Thread

roughing 800 rpm

70 m/min

(230 fpm)

1.6 mm

(0.063 in.)

0.15 mm/rev

(0.0059 ipr)

Coated

carbide

Threadfinishing 800

70(230)

0.1(0.004)

0.15(0.0059) Cermet

Typical Production Rates for Various CuttingOperations


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TABLE 8.15Operation Rate

Turning

Engine lathe Very low to low

Tracer lathe Low to medium

Turret lathe Low to mediumComputer-control lathe Low to medium

Single-spindle chuckers Medium to high

Multiple-spindle chuckers High to very high

Boring Very low

Drilling Low to mediumMilling Low to medium

Planing Very low

Gear cutting Low to medium

Broaching Medium to highSawing 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 perhour; very high is 1000 or more parts per hour.

Dimensional Tolerances


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Figure extra The range of dimensional

tolerances obtained in various machiningprocesses as a function of workpiecesize. Note that there is an order ofmagnitude difference between small andlarge workpieces. Source: Adapted fromManufacturing Planning and EstimatingHandbook, McGraw-Hill, 1963.

General Troubleshooting Guide for TurningOperations


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Operations

TABLE extra

Problem Probable causes

Tool breakage Tool material lacks toughness; improper tool angles; machine tool lacks stiffness; worn bearings and

machine components; cutting parameters too high.

Excessive tool wear Cutting parameters too high; improper tool material; ineffective cutting fluid; improper tool angles.Rough surface finish Built-up edge on tool; feed too high; tool too sharp, chipped or worn; vibration and chatter.Dimensional variability Lack of stiffness; excessive temperature rise; tool wear.

Tool chatter Lack of stiffness; workpiece not supported rigidly; excessive tool overhang.


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Examplesof Threads

Figure extra (a)Standard nomenclature

for screw threads. (b)Unified National threadand identification ofthreads. (c) ISO metricthread and identification

of threads.


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Cutting Screw Threads Forming for large quantity


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Figure extra (a) Cutting screw threads on a lathe with a single-point cutting tool. (b) Cutting screw threads witha single-point tool in several passes, normally utilized for large threads. The small arrows in the figures showthe direction of feed, and the broken lines show the position of the cutting tool as time progresses. Note that inradial cutting, the tool is fed directly into the workpiece. In flank cutting, the tool is fed into the piece along theright face of the thread. In incremental cutting, the tool is first fed directly into the piece at the center of thethread, then at its sides, and finally into the root. (c) A typical carbide insert and tool holder for cutting screw

threads. (d) Cutting internal screw threads with a carbide insert. (See also Figs. 21.2 and 21.3.)


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Threading Die

Figure extra (a) Straight chasers for cutting threads on a lathe. (b) Circular chasers. (c) A solidthreading die.

Swiss-Type Automatic Screw Machine


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Figure extra Schematic illustration of aSwiss-type automatic screw machine.Source: George Gorton MachineCompany.

High production rate of screws

Similar threaded parts

Boring

Figure 8 58 (a) Schematic illustration of a steel boring bar with a carbide insert Note the


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Figure 8.58 (a) Schematic illustration of a steel boring bar with a carbide insert. Note the

passageway in the bar for cutting fluid application. (b) Schematic illustration of a boring bar withtungsten-alloy inertia disks sealed in the bar to counteract vibration and chatter during boring.This system is effective for boring bar length-to-diameter ratios of up to 6. (c) Schematic illustrationof the components of a vertical boring mill. Source: Kennametal Inc.

Producing circular internal profiles in hollow workpieces or on a hole

Horizontal Boring Mill


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Figure extra Horizontal boring mill.Source: Giddings and Lewis, Inc.

For large workpieces

Drills VIDEO

High length-to-diameterti d h l


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Figure extra Varioustypes of drills

ratio deep holes

Other types:

Counterboring drill

Countersinking drill

Core drill

Center drill

Crankshaft drill

Trepanning technique

fND

MRR

4

2=

Drill Point Geometries


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Figure 8.59 (a) Standard chisel-point drill indicating various features. The function of the pair of margins is toprovide a bearing surface for the drill against walls of the hole as it penetrates into the workpiece; drills with fourmargins (double-margin) are available for improved drill guidance and accuracy. Drills with chip-breakerfeatures are also available. (b) Crankshaft-point drill. (c) Various drill points and their manufacturers: 1. Four-

facet split point, by Komet of America. 2. SE point, by Hertel. 3. New point, by Mitsubishi Materials. 4. Hosoipoint, by OSG Tap and Die. 5. Helical point.

General Recommendations for Drill Geometry


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TABLE extra General Recommendations for Drill Geometry for High-Speed Twist Drills

Workpiece

material

Point

angle

Lip-relief

angle

Chisel-edge

angle

Helix

angle Point

Aluminum alloys 90118 1215 125135 2448 Standard

Magnesium alloys 70118 1215 120135 3045 Standard

Copper alloys 118 1215 125135 1030 StandardSteels 118 1015 125135 2432 Standard

High-strength steels 118135 710 125135 2432 CrankshaftStainless steels,

low strength

118 1012 125135 2432 Standard

Stainless steels,

high strength

118135 710 120130 2432 Crankshaft

High-temp. alloys 118135 912 125135 1530 Crankshaft

Refractory alloys 118 710 125135 2432 StandardTitanium alloys 118135 710 125135 1532 Crankshaft

Cast irons 118 812 125135 2432 Standard

Plastics 6090 7 120135 29 Standard

Drilling and Reaming Operations


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Figure 8.60 Varioustypes of drilling andreaming operations.

Gun Drilling


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Figure extra (a) A gun drill showingvarious features. (b) Method of gundrilling. Source: Eldorado Tool andManufacturing Corporation.

Special drill for cutting fluidand chips

Hole depth-to-diameterratios ~ or > 300

Trepanning


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Figure extra (a) Trepanning tool. (b) Trepanning with a drill-mounted single cutter.

Removal of disk-shaped piece

Capabilities of Drilling and Boring


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p g g

Operations

TABLE extra

Diameter Hole depth/diameter

Tool type

range

(mm) Typical Maximum

Twist 0.5150 8 50

Spade 25150 30 100Gun 250 100 300

Trepanning 40250 10 100

Boring 31200 5 8

General Recommendations for Speeds andFeeds in Drilling


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Feeds in Drilling

TABLE extra

Surface speed

Feed, mm/rev (in/rev)

Drill Diameter RPM

Workpiecematerial m/min ft/min 1.5 mm (0.060 in.) 12.5 mm (0.5 in.) 1.5 mm 12.5 mm

Aluminum alloys 30120 100400 0.025 (0.001) 0.30 (0.012) 640025,000 8003000

Magnesium alloys 45120 150400 0.025 (0.001) 0.30 (0.012) 960025,000 11003000

Copper alloys 1560 50200 0.025 (0.001) 0.25 (0.010) 320012,000 4001500Steels 2030 60100 0.025 (0.001) 0.30 (0.012) 43006400 500800

Stainless steels 1020 4060 0.025 (0.001) 0.18 (0.007) 21004300 250500

Titanium alloys 620 2060 0.010 (0.0004) 0.15 (0.006) 13004300 150500Cast irons 2060 60200 0.025 (0.001) 0.30 (0.012) 430012,000 5001500

Thermoplastics 3060 100200 0.025 (0.001) 0.13 (0.005) 640012,000 8001500

Thermosets 2060 60200 0.025 (0.001) 0.10 (0.004) 430012,000 5001500

Note: As hole depth increases, speeds and feeds should be reduced. Selection of speeds

and feeds also depends on the specific surface finish required.

General Troubleshooting and Drill Life

TABLE extra General Troubleshooting Guide for Drilling Operations


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TABLE extra General Troubleshooting Guide for Drilling Operations


Drill breakage Dull drill; drill seizing in hole because of chips clogging flutes; feed too high; lip

relief angle too small.

Excessive drill wear Cutting speed too high; ineffective cutting fluid; rake angle too high; drill burned

and strength lost when sharpened.

Tapered hole Drill misaligned or bent; lips not equal; web not central.Oversize hole Same as above; machine spindle loose; chisel edge not central; side pressure on

workpiece.

Poor hole surface finish Dull drill; ineffective cutting fluid; welding of workpiece material on drill margin;

improperly ground drill; improper alignment.

Figure extra The determination of drill life bymonitoring the rise in force or torque as a function ofthe number of holes drilled. This test is also used fordetermining tap life.

Drilling Machines

(a)


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Figure extra Schematic illustration of components of (a) a vertical drill press and (b) aradial drilling machine.

(a)

CNC Drilling Machine


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Figure extra A three-axis computernumerical control drilling machine. The

turret holds as much as eight differenttools, such as drills, taps, and reamers.

Reamers


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Figure 8.61 (a)Terminology for ahelical reamer. (b)Inserted-bladeadjustable reamer.

To improve:

Dimensional

accuracySurface finish

of existing holes


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Tapping and Taps

Figure 8.62 (a) Terminology for a tap. (b) Tapping of steel nuts in production.

Internal threads in workpieces


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Machining Processes Used to Produce

Various Shapes

Examples of Parts Produced Using theMachining Processes in the Chapter


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Figure 8.63 Typical parts and shapes produced with the machining processes described in this chapter.

Examples of Milling Cutters and Operations


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Figure extra Some of the basic types of milling cutters and milling operations.

Milling cutter: multitooth tool number of chips in one revolution

Efficient way of machining various shapes

Example of Part Produced on a CNC MillingMachine


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Figure extra A typical part that canbe produced on a milling machineequipped with computer controls.Such parts can be made efficientlyand repetitively on computernumerical control (CNC) machines,without the need for refixturing orreclamping the part.

Conventional and Climb Milling: slab milling

Fi 8 64 ( ) S h ti ill t t i f ti l illi d li b illi (b) Sl b illi


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Figure 8.64 (a) Schematic illustration of conventional milling and climb milling. (b) Slab millingoperation, showing depth of cut, d, feed per tooth,f, chip depth of cut, tc, and workpiece speed, v.(c) Schematic illustration of cutter travel distance lc to reach full depth of cut.

Up milling: no effect of surface contamination on tool life, smooth process upward (clamping), tendency to chatter

Down milling: holding the workpieces impact force (rigid setup)

Summary of Milling Parameters and Formulas

TABLE 23.1

N = Rotational speed of the milling cutter, rpm

f F d /t th i /t th


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f = Feed, mm/tooth or in./toothD = Cutter diameter, mm or in.

n = Number of teeth on cutter

v = Linear speed of the workpiece or feed rate, mm/min or in./min

V = Surface speed of cutter, m/min or ft/min

= D N

f = Feed per tooth, mm/tooth or in/tooth

=v /N n

l = Length of cut, mm or in.

t = Cutting time, s or min=( l+lc ) v , where lc =extent of the cutters first contact with workpiece

MRR = mm3/min or in.

3/min

=w d v , where w is the width of cut

Torque = N-m or lb-ft

( Fc ) (D/2)Power = kW or hp

= (Torque) (), where = 2Nradians/min

Note: The units given are those that are commonly used; however, appropriate units must be

used in the formulas.


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Effects of Insert Shapes


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Figure extra Schematic illustration of the effect of insert shape on feed marks on a face-milledsurface: (a) small corner radius, (b) corner flat on insert, and (c) wiper, consisting of a small radiusfollowed by a large radius which leaves smoother feed marks. Source: Kennametal Inc. (d) Feedmarks due to various insert shapes.

Face-Milling Cutter


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Figure 8.66 Terminology for a face-milling cutter.

Effect of Lead Angle

Figure 8 67 The effect of lead angle on the undeformed chip thickness in face milling Note that asthe lead angle increase the chip thickness decreases but the length of contact (i e chip width)


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Figure 8.67 The effect of lead angle on the undeformed chip thickness in face milling. Note that asthe lead angle increase, the chip thickness decreases, but the length of contact (i.e., chip width)increases. The insert in (a) must be sufficiently large to accommodate the contact length increase.

Increase of lead angle decrease of undeformed chip thicknessincrease of contact length

Lead angle: 0o to 45o for most face-milling cutters

Cutter and Insert Position in Face Milling

Figure 8 68 (a) Relative position of the


94/135

Figure 8.68 (a) Relative position of thecutter and insert as it first engages theworkpiece in face milling, (b) insertpositions towards the end of the cut,and (c) examples of exit angles of

insert, showing desirable (positive ornegative angle) and undesirable (zeroangle) positions. In all figures, thecutter spindle is perpendicular to thepage.

Cutters for Different Types of Milling

Figure 8.69 Cutters for (a) straddle milling,(b) form milling (c) slotting and (d) slitting


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(b) form milling, (c) slotting, and (d) slittingwith a milling cutter.

Figure extra (a) T-slot cutting with amilling cutter. (b) A shell mill.


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Capacities and Maximum WorkpieceDimensions for Machine Tools


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TABLE extra Typical Capacities and Maximum Workpiece Dimensions for

Some Machine Tools

Machine tool

Maximum dimension

m (ft)

Power

(kW)

Maximum

speedMilling machines (table travel)

Knee-and-column 1.4 (4.6) 20 4000 rpm

Bed 4.3 (14)

Numerical control 5 (16.5)Planers (table travel) 10 (33) 100 1.7

Broaching machines (length) 2 (6.5) 0.9 MN

Gear cutting (gear diameter) 5 (16.5)

Note: Larger capacities are available for special applications.

TABLE extra Approximate Cost of Selected Tools for Machining*Tools Size (in.) Cost ($)

Drills, HSS, straight shank 1/4 1.002.00

1/2 3.006.00

Coated (TiN) 1/4 2.603.00

1/2 1015Tapered shank 1/4 2 50 7 00


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Approximate

Cost ofSelected Toolsfor Machining

Tapered shank 1/4 2.507.00

1 1545

2 80853 250

4 950

Reamers, HSS, hand 1/4 10151/2 1015

Chucking 1/2 510

1 2025

1 1/2 4055

End mills, HSS 1/2 1015

1 1530Carbide-tipped 1/2 3035

1 4560

Solid carbide 1/2 3070

1 180

Burs, carbide 1/2 1020

1 5060

Milling cutters, HSS, staggered tooth, wide 4 3575

8 130260Collets (5 core) 1 1020

*Cost depends on the particular type of material and shape of tool, its quality,

and the amount purchased.


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General Troubleshooting Guide for MillingOperations

TABLE extraP bl P b bl


100/135


Tool breakage Tool material lacks toughness; improper tool angles; cutting

parameters too high.

Tool wear excessive Cutting parameters too high; improper tool material; improper tool

angles; improper cutting fluid.

Rough surface finish Feed too high; spindle speed too low; too few teeth on cutter; tool

chipped or worn; built-up edge; vibration and chatter.

Tolerances too broad Lack of spindle stiffness; excessive temperature rise; dull tool; chips

clogging cutter.

Workpiece surface

burnished

Dull tool; depth of cut too low; radial relief angle too small.

Back striking Dull cutting tools; cutter spindle tilt; negative tool angles.

Chatter marks Insufficient stiffness of system; external vibrations; feed, depth, and

width of cut too large.Burr formation Dull cutting edges or too much honing; incorrect angle of entry or

exit; feed and depth of cut too high; incorrect insert geometry.

Breakout Lead angle too low; incorrect cutting edge geometry; incorrect angle

of entry or exit; feed and depth of cut too high.


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102/135


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Additional Milling Machines

Figure 23.18 A computer numerical control, vertical-spindle milling machine. This machine is one of the most


104/135

versatile machine tools. Source: Courtesy of BridgeportMachines Division, Textron Inc.

Figure 23.19 Schematic illustration of a five-axisprofile milling machine. Note that there are threeprincipal linear and two angular movements ofmachine components

Examples of Parts Made on a Planer and byBroaching

Figure extra Typical parts that canb d l


105/135

be made on a planer.

Figure 8.72 (a) Typical parts made by internalbroaching. (b) Parts made by surface broaching.Heavy lines indicate broached surfaces. Source:General Broach and Engineering Company.

Large workpieces with flatsurfaces or various cross-

sections with grooves andnotches

Shaping with multiple teeth internaland external surfaces: holes ofcircular, square or irregular section,

keyways,

Broaches


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Figure 8.73 (a) Cutting action of a broach, showing various features. (b) Terminology for a broach.

lkpitch =l: surface length

k: 1.76 for l in mm, 0.35 for l in inches

Push broaches: shorter 150~350 mm

Pull broaches: longer

Chipbreakers and a Broaching Machine

( ) ( )

Figure extra Chipbreaker features on (a) a flat broach and (b) a round broach. (c) Verticalbroaching machine. Source: Ty Miles, Inc.


107/135

(a)

(b)

(c)


108/135

Broaching Internal Splines


109/135

Figure extra


110/135


111/135


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Spur Gear

Fi t N l t f i l t

Gear manufacturing by cutting


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Figure extra Nomenclature for an involute spur gear.


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Examples of Parts Machined on Machining

Centers


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Figure 8.79 Examples of parts that can be machined on machining centers, using variousprocesses such as turning, facing, milling, drilling, boring, reaming, and threading. Such partswould ordinarily require a variety of machine tools. Source: Toyoda Machinery.


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Examples of Machining Complex Shapes


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Figure 8.89

Fundamentals of Cutting - Manufacturing

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