Transcript No Slide Title

CHAPTER 8
MaterialRemoval
Processes:
Cutting
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 1
Cutting Processes
FIGURE 8.1 Examples of cutting processes.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 2
Orthogonal Cutting
FIGURE 8.2 Schematic illustration of a two-dimensional cutting process (also called
orthogonal cutting).
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 3
Chip Formation
FIGURE 8.3 (a) Schematic illustration of the basic mechanism of chip formation in cutting.
(b) Velocity diagram in the cutting zone.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 4
Chips Produced in Metal Cutting
FIGURE 8.4 Basic types
of chips produced in metal
cutting and their
micrographs: (a)
continuous chip with
narrow, straight primary
shear zone; (b) secondary
shear zone at the tool-chip
interface; (c) continuous
chip with built-up edge; (d)
continuous chip with large
primary shear zone; (e)
segmented or
nonhomogeneous chip; and
(f) discontinuous chip.
Source: After M. C. Shaw,
P. K. Wright, and S.
Kalpakjian.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 5
Continuous Chip Formation
FIGURE 8.5 Shiny (burnished) surface on the tool side of a continuous chip produced in
turning.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
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Chips Produced In Turning
FIGURE 8.8 Various chips produced in turning: (a) tightly curled chip; (b) chip hits
workpiece and breaks; (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.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 7
Oblique Cutting
FIGURE 8.9 (a) Schematic illustration of cutting with an oblique tool. (b) Top view,
showing the inclination angle i. (c) Types of chips produced with different inclination
angles.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
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Right-Hand Cutting Tool
FIGURE 8.10 (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
by carbide or other inserts of various shapes and sizes, as shown in (b).
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 9
Terminology in Lathe Turning
FIGURE 8.19
Terminology used in a
turning operation on a
lathe, where f is the feed
(in./rev or mm/rev) and d
is the depth of cut. Note
that feed in turning is
equivalent to the depth of
cut in orthogonal cutting
(Fig. 8.2), and the depth
of cut in turning is
equivalent to the turning
is equivalent to the width
of cut in orthogonal
cutting. See also Fig. 8.42.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 10
Types of Cutting Tool
Wear
FIGURE 8.20 (a) Types of wear
observed in cutting tools. The thermal
cracks shown are usually observed in
interrupted cutting operations, such as in
milling. (b) Catastrophic failure of tools.
(c) Features of tool wear in a turning
operation. The VB indicates average
flank wear. Source: (a) and (b) After V.
C. Venkatesh. (c) International
Organization for Standardization (ISO).
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 11
Crater and Flank Wear on a Tool
FIGURE 8.21 (a) Crater wear and (b) flank wear on a carbide tool. Source: J. C, Keefe,
Lehigh University.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 12
Range of
Surface
Roughnesses
FIGURE 8.27
Range of surface
roughnesses
obtained in various
machining
processes. Note the
wide range within
each group. (See
also Fig. 9.27).
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 13
Carbide Inserts
FIGURE 8.32 (a) Typical
carbide inserts with various
shapes and chip-breaker
features. Round inserts are
also available. The holes in
the inserts are standardized
for interchangeability.
Source: Courtesy of
Kyocera Engineered
Ceramics, Inc., and
Manufacturing
Engineering, Society of
Manufacturing Engineers.
(b) Methods of attaching
inserts to a tool shank by
clamping, (c) with wing
lockpins, and (d) with a
brazed insert on a shank.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
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Relative
Edge
Strength
FIGURE 8.33 Relative edge strength and tendency for chipping and breaking of inserts
with various shapes. Strength refers to that of the cutting edge shown by the included angles.
Source: Kennametal, Inc.
FIGURE 8.34 Edge preparation of
inserts to improve edge strength.
Source: Kennametal, Inc.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 15
Properties of Tool Materials
FIGURE 8.38 Ranges of properties for various groups of tool materials. (See also various
tables in this chapter.)
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 16
Construction of Insert
FIGURE 8.39 Construction of polycrystalline cubic-boron-nitride or diamond layer on a
tungsten-carbide insert.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 17
Process
Characteristics
Turning
Turning and facing operations on all types of
materials; requires skilled labor; low production rate,
but medium to high with turret lathes and automatic
machines, requiring less-skilled labor.
Internal surfaces or prof iles, with characteristics
similar to turning; stif fness of boring bar important to
avoid chatter.
Round holes of v arious sizes and depths; requires
boring and reaming for improv ed accuracy; high
production rate; labor skill required depends on hole
location and accuracy specif ied.
Variety of shapes involv ing contours, flat surfaces,
and slots; wide variety of tooling; versatile; low to
medium production rate; requires skilled labor.
Flat surfaces and straight contour profiles on large
surfaces; suitable f or low-quantity production; labor
skill required depends on part shape.
Flat surfaces and straight contour profiles on relativ ely
small workpieces; suitable for low-quantity production;
labor skill required depends on part shape.
External and internal flat surf aces, slots and contours
with good surface f inish; costly tooling; high
production rate; labor skill required depends on part
shape.
Straight and contour cuts on flats 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.
Boring
Drilling
Mill ing
Planing
Shaping
Broaching
Sawing
Commercial tolerances
(±mm)
Fine: 0.05-0.13
Rough: 0.13
Skiving: 0.025-0.05
Machining
Processes
0.025
0.075
0.13-0.25
0.08-0.13
0.05-0.13
TABLE 8.7 General
characteristics of machining
processes.
0.025-0.15
0.8
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 18
Lathe
Operations
FIGURE 8.40 Various
cutting operations that can
be performed on a lathe.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 19
Designations for a
Right-Handed Cutting
Tool
FIGURE 8.41 (a) Designations and symbols for a
right-hand cutting tool; solid high-speed-steel
tools have a similar designation. The designation
“right hand” means that the tool travels from right
to left, as shown in Fig. 8.19 (b) Square insert in a
right-hand toolholder for a turning operation. A
wide variety of toolholder is available for holding
inserts at various angles. Thus, the angles shown
in (a) can be achieved easily by selecting an
appropriate insert and toolholder. Source:
Kennametal, Inc.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 20
Turning Operation
FIGURE 8.42 (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 tool in turning. Fc is the cutting force; Ft is the thrust or feed force (in the
direction of feed); and Fr is the radial force that tends to push the tool away from the
workpiece being machined. Compare this figure with Fig. 8.11 for a two-dimensional cutting
operation.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 21
Range of Cutting Speeds
FIGURE 8.43 The range of applicable cutting speeds and fees for a variety of tool
materials. Source: Valenite, Inc.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 22
Cutting Speeds in Turning
W ORKPIECE MATERIAL
Aluminum alloys
Cast iron, gray
Copper alloys
High-temperature alloys
Steels
Stainless steels
Thermoplastics and thermosets
Titanium alloys
Tungsten alloys
CUTTING SPEED
m/min
200-1000
60-900
50-700
20-400
50-500
50-300
90-240
10-100
60-150
ft/min
650-3300
200-3000
160-2300
65-1300
160-1600
160-1000
300-800
30-330
200-500
Note: (a) These speeds are f or carbides and ceramic cutting tools. Speeds for high-speed steel
tool are lower than indicated. The higher ranges are f or coated carbides and cermets. Speeds f or
diamond tools are signif icantly higher than those indicated.
(b) Depths of cut, d, are generally in the range of 0.5-12 mm (0.02-0.5 in.)
(c) Feeds, f, are generally in the range of 0.15-1 mm/rev (0.006-0.040 in./rev ).
TABLE 8.8 Approximate range of recommended cutting speeds for turning operations.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 23
Components of a Lathe
FIGURE 8.44 Schematic illustration of the components of a lathe. Source: Courtesy of
Heidenreich & Harbeck.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 24
Machine Tool Parts Example
FIGURE 8.46 Typical parts made on computer-numerical-control machine tools.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 25
Chisel and Crankshaft-Point Drills
FIGURE 8.48 (a) Standard chisel-point drill, with various features indicated. (b)
Crankshaft-point drill.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 26
Drills and Drilling Operations
FIGURE 8.49 Various types of drills and drilling operations.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 27
Speeds and Feeds in Drilling
WORKPIECE
MATERIAL
Alumi num alloys
Magnesium alloys
Copper alloys
Steels
Stainless steels
Titanium a lloys
Cast irons
Thermoplastics
Thermosets
SURFACE
SPEED
m/min
ft/min
30-120
45-120
15-60
20-30
10-20
6-20
20-60
30-60
20-60
100-400
150-400
50-200
60-100
40-60
20-60
60-200
100-200
60-200
FEED, mm/rev (in./rev)
DRILL DIAMETER
1.5 mm
12.5 mm
(0.060 in.)
(0.5 in.)
0.025 (0.001)
0.025 (0.001)
0.025 (0.001)
0.025 (0.001)
0.025 (0.001)
0.010 (0.0004)
0.025 (0.001)
0.025 (0.001)
0.025 (0.001)
0.30 ( 0.012)
0.30 ( 0.012)
0.25 ( 0.010)
0.30 ( 0.012)
0.18 ( 0.007)
0.15 ( 0.006)
0.30 ( 0.012)
0.13 ( 0.005)
0.10 ( 0.004)
RPM
1.5 mm
12.5 mm
6400-25,000
9600-25,000
3200-12,000
4300-6400
2100-4300
1300-4300
4300-12,000
6400-12,000
4300-12,000
800-3000
1100-3000
400-1500
500-800
250-500
150-500
500-1500
800-1500
500-1500
Note: As hole depth increases, speeds and feeds should be reduced. Selection of speeds and
feeds also depends on the specific surf ace finish required.
TABLE 8.10 General recommendations for speeds and feeds in drilling.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 28
Reamer and Tap Terminology
FIGURE 8.50 Terminology for a helical reamer.
FIGURE 8.51 Terminology for a tap.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 29
Milling Operations
FIGURE 8.53 (a) Schematic illustration of conventional milling and climb milling. (b)
Slab-milling operation, 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 to reach full depth of
cut.
Manufacturing Processes for Engineering Materials, 4th ed.
Kalpakjian • Schmid
Prentice Hall, 2003
page 30