fundamentals of cutting - manufacturing
TRANSCRIPT
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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
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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)
Al2O3 ceramic " 0.25
(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)
Al2O3 ceramic " 0.25
(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
(300-750)Polycrystalline
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
(350-950)Polycrystalline
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
Problem Probable causes
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
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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
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Problem Probable causes
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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Additional Milling Machines
Figure 23.18 A computer numerical control, vertical-spindle milling machine. This machine is one of the most
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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
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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.
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(a)
(b)
(c)
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Broaching Internal Splines
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Figure extra
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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