Mpemch08(Cutting) 1

5/27/2018 Mpemch08(Cutting) 1

1/30

Manufacturing Processes for Engineering Materials, 4th ed.

Kalpakjian Schmid

Prentice Hall, 2003 page 1

CHAPTER 8

Material-

Removal

Processes:Cutting


2/30


Kalpakjian Schmid


Cutting Processes

FIGURE 8.1 Examples of cutting processes.


3/30


Kalpakjian Schmid


Orthogonal Cutting

FIGURE 8.2 Schematic illustration of a two-dimensional cutting process (also called

orthogonal cutting).


4/30


Kalpakjian Schmid


Chip Formation

FIGURE 8.3 (a) Schematic illustration of the basic mechanism of chip formation in cutting.(b) Velocity diagram in the cutting zone.


5/30


Kalpakjian Schmid


Chips Produced in Metal Cutting

FIGURE 8.4 Basic typesof chips produced in metal

cutting and theirmicrographs: (a)continuous chip withnarrow, straight primaryshear zone; (b) secondaryshear zone at the tool-chipinterface; (c) continuous

chip with built-up edge; (d)continuous chip with largeprimary shear zone; (e)segmented ornonhomogeneous chip; and(f) discontinuous chip.Source: After M. C. Shaw,

P. K. Wright, and S.Kalpakjian.


6/30


Kalpakjian Schmid


Continuous Chip Formation

FIGURE 8.5 Shiny (burnished) surface on the tool side of a continuous chip produced in

turning.


7/30


Kalpakjian Schmid


Chips Produced In Turning

FIGURE 8.8 Various chips produced in turning: (a) tightly curled chip; (b) chip hitsworkpiece and breaks; (c) continuous chip moving away from workpiece; and (d) chip hitstool shank and breaks off. Source: G. Boothroyd,Fundamentals of Metal Machining and

Machine Tools.


8/30


Kalpakjian Schmid


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.


9/30


Kalpakjian Schmid


Right-Hand Cutting Tool

FIGURE 8.10 (a) Schematic illustration of a right-hand cutting tool. Although these toolshave traditionally been produced from solid tool-steel bars, they have been largely replacedby carbide or other inserts of various shapes and sizes, as shown in (b).


10/30


Kalpakjian Schmid


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.


11/30


Kalpakjian Schmid


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).


12/30


Kalpakjian Schmid


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.


13/30


Kalpakjian Schmid


Range of

Surface

Rough-nesses

FIGURE 8.27Range of surfaceroughnessesobtained in variousmachiningprocesses. Note thewide range withineach group. (Seealso Fig. 9.27).


14/30


Kalpakjian Schmid


Carbide InsertsFIGURE 8.32 (a) Typicalcarbide inserts with various

shapes and chip-breakerfeatures. Round inserts arealso available. The holes inthe inserts are standardizedfor interchangeability.Source: Courtesy ofKyocera EngineeredCeramics, Inc., and

ManufacturingEngineering, Society ofManufacturing Engineers.(b) Methods of attachinginserts to a tool shank byclamping, (c) with winglockpins, and (d) with a

brazed insert on a shank.


15/30


Kalpakjian Schmid


Relative

Edge

Strength

FIGURE 8.33 Relative edge strength and tendency for chipping and breaking of insertswith 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.


16/30


Kalpakjian Schmid


Properties of Tool Materials

FIGURE 8.38 Ranges of properties for various groups of tool materials. (See also various

tables in this chapter.)


17/30


Kalpakjian Schmid


Construction of Insert

FIGURE 8.39 Construction of polycrystalline cubic-boron-nitride or diamond layer on atungsten-carbide insert.


18/30


Kalpakjian Schmid


Machining

Processes

TABLE 8.7 Generalcharacteristics of machining

processes.

Process Characteristics Commercial tolerances(mm)

Turning Turning and facing operations on all types ofmaterials; requires skilled labor; low production rate,but medium to high with turret lathes and automaticmachines, requiring less-skilled labor.

Fine: 0.05-0.13Rough: 0.13Skiving: 0.025-0.05

Boring Internal surfaces or profiles, with characteristicssimil ar to turning; stif fness of boring bar important toavoid chatter.

0.025

Drilling Round holes of various sizes and depths; requiresboring and reaming for improved accuracy; highproduction rate; labor skill required depends on holelocation and accuracy specified.

0.075

Mill ing Variety of shapes involving contours, flat surfaces,and slots; wide variety of tooling; versatile; low tomedium production rate; requires skill ed labor.

0.13-0.25

Planing Flat surfaces and straight contour profiles on largesurfaces; suitable for low-quantity production; laborskill required depends on part shape.

0.08-0.13

Shaping Flat surfaces and straight contour profiles on relativelysmal l workpieces; suitable for low-quantity production;labor skill required depends on part shape.

0.05-0.13

Broaching External and internal flat surfaces, slots and contourswith good surface f inish; costly tooling; highproduction rate; labor skill required depends on partshape.

0.025-0.15

Sawing Straight and contour cuts on flats or structural shapes;

not suitable for hard materials unless saw has carbideteeth or is coated with diamond; low production rate;requires only low labor skill.

0.8


19/30


Kalpakjian Schmid


Lathe

Operations

FIGURE 8.40 Variouscutting operations that canbe performed on a lathe.


20/30


Kalpakjian Schmid


Designations for a Right-

Handed Cutting Tool

FIGURE 8.41 (a) Designations and symbols for aright-hand cutting tool; solid high-speed-steeltools have a similar designation. The designationright hand means that the tool travels from rightto left, as shown in Fig. 8.19 (b) Square insert in aright-hand toolholder for a turning operation. Awide variety of toolholder is available for holdinginserts at various angles. Thus, the angles shownin (a) can be achieved easily by selecting anappropriate insert and toolholder. Source:Kennametal, Inc.


21/30


Kalpakjian Schmid


Turning Operation

FIGURE 8.42 (a) Schematic illustration of a turning operation showing depth of cut,d, andfeed,f. cutting speed is the surface speed of the workpiece at the tool tip. (b) Forces actingon a cutting tool in turning.Fcis the cutting force;Ftis the thrust or feed force (in thedirection of feed); andFris 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-dimensionalcutting operation.


22/30


Kalpakjian Schmid


Range of Cutting Speeds

FIGURE 8.43 The range of applicable cutting speeds and fees for a variety of tool

materials. Source: Valenite, Inc.


23/30


Kalpakjian Schmid


Cutting Speeds in Turning

TABLE 8.8 Approximate range of recommended cutting speeds for turning operations.

CUTT ING SPEEDWORKPIECE MATERIAL

m/min ft/min

Aluminum alloys

Cast iron, grayCopper alloys

High-temperature alloysSteels

Stainless steelsThermoplastics and thermosets

Titanium alloys

Tungsten alloys

200-1000

60-90050-700

20-40050-500

50-30090-240

10-100

60-150

650-3300

200-3000160-2300

65-1300160-1600

160-1000300-800

30-330

200-500

Note:(a) These speeds are for carbides and ceramic cutting tools. Speeds for high-speed steel

tool are lower than indicated. The higher ranges are for coated carbides and cermets. Speeds fordiamond tools are significantly 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).


24/30


Kalpakjian Schmid


Components of a Lathe

FIGURE 8.44 Schematic illustration of the components of a lathe.Source: Courtesy of

Heidenreich & Harbeck.


25/30


Kalpakjian Schmid


Machine Tool Parts Example

FIGURE 8.46 Typical parts made on computer-numerical-control machine tools.


26/30


Kalpakjian Schmid


Chisel and Crankshaft-Point Drills

FIGURE 8.48 (a) Standard chisel-point drill, with various features indicated. (b)

Crankshaft-point drill.


27/30


Kalpakjian Schmid


Drills and Drilling Operations

FIGURE 8.49 Various types of drills and drilling operations.


28/30


Kalpakjian Schmid


Speeds and Feeds in Drilling

TABLE 8.10 General recommendations for speeds and feeds in drilling.

SURFACE

SPEED

FEED, mm/rev (in./rev)

DRILL DIAMET ER

RPMWORKPIECE

MATERIALm/min ft/min 1.5 mm

(0.060 in.)12.5 mm(0.5 in.)

1.5 mm 12.5 mm

Aluminum alloysMagnesium alloysCopper alloysSteelsStainless steels

Titanium alloysCast ironsThermoplasticsThermosets

30-12045-12015-6020-3010-20

6-2020-6030-6020-60

100-400150-40050-20060-10040-60

20-6060-200

100-20060-200

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)

6400-25,0009600-25,0003200-12,0004300-64002100-4300

1300-43004300-12,0006400-12,0004300-12,000

800-30001100-3000400-1500500-800250-500

150-500500-1500800-1500500-1500

Note:As hole depth increases, speeds and feeds should be reduced. Selection of speeds andfeeds also depends on the specific surface finish required.


29/30


Kalpakjian Schmid


Reamer and Tap Terminology

FIGURE 8.50 Terminology for a helical reamer.

FIGURE 8.51 Terminology for a tap.


30/30


Kalpakjian Schmid


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; andworkpiece speed, v. (c) Schematic illustration of cutter travel distance to reach full depth ofcut.

Documents

Mpemch08(Cutting) 1