E1C21 11/11/2009 15:44:1 Page 483 Part VI Material Removal Processes 21 THEORY OF METAL MACHINING Chapter Contents 21.1 Overview of Machining Technology 21.2 Theory of Chip Formation in Metal Machining 21.2.1 The Orthogonal Cutting Model 21.2.2 Actual Chip Formation 21.3 Force Relationships and the Merchant Equation 21.3.1 Forces in Metal Cutting 21.3.2 The Merchant Equation 21.4 Power and Energy Relationships in Machining 21.5 Cutting Temperature 21.5.1 Analytical Methods to Compute Cutting Temperatures 21.5.2 Measurement of Cutting Temperature The material removal processes are a family of shaping operations (Figure 1.4) in which excess material is removed from a starting workpart so that what remains is the desired final geometry The ‘‘family tree’’ is shown in Figure 21.1 The most important branch of the family is conventional machining, in which a sharp cutting tool is used to mechanically cut the material to achieve the desired geometry The three principal machining processes are turning, drilling, and milling The ‘‘other machining operations’’ in Figure 21.1 include shaping, planing, broaching, and sawing This chapter begins our coverage of machining, which runs through Chapter 24 Another group of material removal processes is the abrasive processes, which mechanically remove material by the action of hard, abrasive particles This process group, which includes grinding, is covered in Chapter 25 The ‘‘other abrasive processes’’ in Figure 21.1 include honing, lapping, and superfinishing Finally, there are the nontraditional processes, which use various energy forms other than a sharp cutting tool or abrasive particles to remove material The energy forms include mechanical, electrochemical, thermal, and chemical.1 The nontraditional processes are discussed in Chapter 26 Machining is a manufacturing process in which a sharp cutting tool is used to cut away material to leave the Some of the mechanical energy forms in the nontraditional processes involve the use of abrasive particles, and so they overlap with the abrasive processes in Chapter 25 483 E1C21 11/11/2009 484 15:44:1 Page 484 Chapter 21/Theory of Metal Machining Turning and related operations Conventional machining Drilling and related operations Milling Other machining operations Material removal processes Abrasive processes Grinding operations Other abrasive processes Mechanical energy processes Nontraditional machining Electrochemical machining Thermal energy processes FIGURE 21.1 Classification of material removal processes Chemical machining desired part shape The predominant cutting action in machining involves shear deformation of the work material to form a chip; as the chip is removed, a new surface is exposed Machining is most frequently applied to shape metals The process is illustrated in the diagram of Figure 21.2 Machining is one of the most important manufacturing processes The Industrial Revolution and the growth of the manufacturing-based economies of the world can be traced largely to the development of the various machining operations (Historical Note 22.1) Machining is important commercially and technologically for several reasons: FIGURE 21.2 (a) A cross-sectional view of the machining process (b) Tool with negative rake angle; compare with positive rake angle in (a) E1C21 11/11/2009 15:44:1 Page 485 Section 21.1/Overview of Machining Technology 485 å Variety of work materials Machining can be applied to a wide variety of work materials Virtually all solid metals can be machined Plastics and plastic composites can also be cut by machining Ceramics pose difficulties because of their high hardness and brittleness; however, most ceramics can be successfully cut by the abrasive machining processes discussed in Chapter 25 å Variety of part shapes and geometric features Machining can be used to create any regular geometries, such as flat planes, round holes, and cylinders By introducing variations in tool shapes and tool paths, irregular geometries can be created, such as screw threads and T-slots By combining several machining operations in sequence, shapes of almost unlimited complexity and variety can be produced å Dimensional accuracy Machining can produce dimensions to very close tolerances Some machining processes can achieve tolerances of Ỉ0.025 mm (Ỉ0.001 in), much more accurate than most other processes å Good surface finishes Machining is capable of creating very smooth surface finishes Roughness values less than 0.4 microns (16 m-in.) can be achieved in conventional machining operations Some abrasive processes can achieve even better finishes On the other hand, certain disadvantages are associated with machining and other material removal processes: å Wasteful of material Machining is inherently wasteful of material The chips generated in a machining operation are wasted material Although these chips can usually be recycled, they represent waste in terms of the unit operation å Time consuming A machining operation generally takes more time to shape a given part than alternative shaping processes such as casting or forging Machining is generally performed after other manufacturing processes such as casting or bulk deformation (e.g., forging, bar drawing) The other processes create the general shape of the starting workpart, and machining provides the final geometry, dimensions, and finish 21.1 OVERVIEW OF MACHINING TECHNOLOGY Machining is not just one process; it is a group of processes The common feature is the use of a cutting tool to form a chip that is removed from the workpart To perform the operation, relative motion is required between the tool and work This relative motion is achieved in most machining operations by means of a primary motion, called the cutting speed, and a secondary motion, called the feed The shape of the tool and its penetration into the work surface, combined with these motions, produces the desired geometry of the resulting work surface Types of Machining Operations There are many kinds of machining operations, each of which is capable of generating a certain part geometry and surface texture We discuss these operations in considerable detail in Chapter 22, but for now it is appropriate to identify and define the three most common types: turning, drilling, and milling, illustrated in Figure 21.3 In turning, a cutting tool with a single cutting edge is used to remove material from a rotating workpiece to generate a cylindrical shape, as in Figure 21.3(a) The speed motion in turning is provided by the rotating workpart, and the feed motion is achieved by the cutting tool moving slowly in a direction parallel to the axis of rotation of the workpiece Drilling is used to create a round hole It is accomplished by a rotating tool that typically has two E1C21 11/11/2009 486 15:44:1 Page 486 Chapter 21/Theory of Metal Machining Speed motion (tool) Work New surface Speed motion (work) Cutting tool Drill bit Feed motion (tool) Feed motion (tool) Work (a) (b) Speed motion Rotation Milling cutter FIGURE 21.3 The three most common types of machining processes: (a) turning, (b) drilling, and two forms of milling: (c) peripheral milling, and (d) face milling New surface Feed motion (work) Milling cutter New surface Feed motion (work) Work Work (c) (d) cutting edges The tool is fed in a direction parallel to its axis of rotation into the workpart to form the round hole, as in Figure 21.3(b) In milling, a rotating tool with multiple cutting edges is fed slowly across the work material to generate a plane or straight surface The direction of the feed motion is perpendicular to the tool’s axis of rotation The speed motion is provided by the rotating milling cutter The two basic forms of milling are peripheral milling and face milling, as in Figure 21.3(c) and (d) Other conventional machining operations include shaping, planing, broaching, and sawing (Section 22.6) Also, grinding and similar abrasive operations are often included within the category of machining These processes commonly follow the conventional machining operations and are used to achieve a superior surface finish on the workpart The Cutting Tool A cutting tool has one or more sharp cutting edges and is made of a material that is harder than the work material The cutting edge serves to separate a chip from the parent work material, as in Figure 21.2 Connected to the cutting edge are two surfaces of the tool: the rake face and the flank The rake face, which directs the flow of the newly formed chip, is oriented at a certain angle called the rake angle a It is measured relative to a plane perpendicular to the work surface The rake angle can be positive, as in Figure 21.2(a), or negative as in (b) The flank of the tool provides a clearance between the tool and the newly generated work surface, thus protecting the surface from abrasion, which would degrade the finish This flank surface is oriented at an angle called the relief angle Most cutting tools in practice have more complex geometries than those in Figure 21.2 There are two basic types, examples of which are illustrated in Figure 21.4: (a) single-point tools and (b) multiple-cutting-edge tools A single-point tool has one cutting edge and is used for operations such as turning In addition to the tool features shown in Figure 21.2, there is one tool point from which the name of this cutting tool is derived During machining, the point of the tool penetrates below the original work surface of the part The point is usually rounded to a certain radius, called the nose radius Multiple-cutting-edge tools have more E1C21 11/11/2009 15:44:1 Page 487 Section 21.1/Overview of Machining Technology 487 FIGURE 21.4 (a) A single-point tool showing rake face, flank, and tool point; and (b) a helical milling cutter, representative of tools with multiple cutting edges than one cutting edge and usually achieve their motion relative to the workpart by rotating Drilling and milling use rotating multiple-cutting-edge tools Figure 21.4(b) shows a helical milling cutter used in peripheral milling Although the shape is quite different from a singlepoint tool, many elements of tool geometry are similar Single-point and multiple-cuttingedge tools and the materials used in them are discussed in more detail in Chapter 23 Cutting Conditions Relative motion is required between the tool and work to perform a machining operation The primary motion is accomplished at a certain cutting speed v In addition, the tool must be moved laterally across the work This is a much slower motion, called the feed f The remaining dimension of the cut is the penetration of the cutting tool below the original work surface, called the depth of cut d Collectively, speed, feed, and depth of cut are called the cutting conditions They form the three dimensions of the machining process, and for certain operations (e.g., most single-point tool operations) they can be used to calculate the material removal rate for the process: RMR ẳ vf d 21:1ị where RMR ẳ material removal rate, mm3/s (in3/min); v ¼ cutting speed, m/s (ft/min), which must be converted to mm/s (in/min); f ¼ feed, mm (in); and d ¼ depth of cut, mm (in) The cutting conditions for a turning operation are depicted in Figure 21.5 Typical units used for cutting speed are m/s (ft/min) Feed in turning is expressed in mm/rev FIGURE 21.5 Cutting speed, feed, and depth of cut for a turning operation E1C21 11/11/2009 488 15:44:1 Page 488 Chapter 21/Theory of Metal Machining (in/rev), and depth of cut is expressed in mm (in) In other machining operations, interpretations of the cutting conditions may differ For example, in a drilling operation, depth is interpreted as the depth of the drilled hole Machining operations usually divide into two categories, distinguished by purpose and cutting conditions: roughing cuts and finishing cuts Roughing cuts are used to remove large amounts of material from the starting workpart as rapidly as possible, in order to produce a shape close to the desired form, but leaving some material on the piece for a subsequent finishing operation Finishing cuts are used to complete the part and achieve the final dimensions, tolerances, and surface finish In production machining jobs, one or more roughing cuts are usually performed on the work, followed by one or two finishing cuts Roughing operations are performed at high feeds and depths—feeds of 0.4 to 1.25 mm/rev (0.015–0.050 in/rev) and depths of 2.5 to 20 mm (0.100–0.750 in) are typical Finishing operations are carried out at low feeds and depths—feeds of 0.125 to 0.4 mm (0.005–0.015 in/rev) and depths of 0.75 to 2.0 mm (0.030–0.075 in) are typical Cutting speeds are lower in roughing than in finishing A cutting fluid is often applied to the machining operation to cool and lubricate the cutting tool (cutting fluids are discussed in Section 23.4) Determining whether a cutting fluid should be used, and, if so, choosing the proper cutting fluid, is usually included within the scope of cutting conditions Given the work material and tooling, the selection of these conditions is very influential in determining the success of a machining operation Machine Tools A machine tool is used to hold the workpart, position the tool relative to the work, and provide power for the machining process at the speed, feed, and depth that have been set By controlling the tool, work, and cutting conditions, machine tools permit parts to be made with great accuracy and repeatability, to tolerances of 0.025 mm (0.001 in) and better The term machine tool applies to any power-driven machine that performs a machining operation, including grinding The term is also applied to machines that perform metal forming and pressworking operations (Chapters 19 and 20) The traditional machine tools used to perform turning, drilling, and milling are lathes, drill presses, and milling machines, respectively Conventional machine tools are usually tended by a human operator, who loads and unloads the workparts, changes cutting tools, and sets the cutting conditions Many modern machine tools are designed to accomplish their operations with a form of automation called computer numerical control (Section 38.3) 21.2 THEORY OF CHIP FORMATION IN METAL MACHINING The geometry of most practical machining operations is somewhat complex A simplified model of machining is available that neglects many of the geometric complexities, yet describes the mechanics of the process quite well It is called the orthogonal cutting model, Figure 21.6 Although an actual machining process is three-dimensional, the orthogonal model has only two dimensions that play active roles in the analysis 21.2.1 THE ORTHOGONAL CUTTING MODEL By definition, orthogonal cutting uses a wedge-shaped tool in which the cutting edge is perpendicular to the direction of cutting speed As the tool is forced into the material, the chip is formed by shear deformation along a plane called the shear plane, which is oriented at an angle f with the surface of the work Only at the sharp cutting edge of the tool does failure of the material occur, resulting in separation of the chip from the parent E1C21 11/11/2009 15:44:1 Page 489 Section 21.2/Theory of Chip Formation in Metal Machining 489 FIGURE 21.6 Orthogonal cutting: (a) as a three-dimensional process, and (b) how it reduces to two dimensions in the side view material Along the shear plane, where the bulk of the mechanical energy is consumed in machining, the material is plastically deformed The tool in orthogonal cutting has only two elements of geometry: (1) rake angle and (2) clearance angle As indicated previously, the rake angle a determines the direction that the chip flows as it is formed from the workpart; and the clearance angle provides a small clearance between the tool flank and the newly generated work surface During cutting, the cutting edge of the tool is positioned a certain distance below the original work surface This corresponds to the thickness of the chip prior to chip formation, to As the chip is formed along the shear plane, its thickness increases to tc The ratio of to to tc is called the chip thickness ratio (or simply the chip ratio) r: rẳ to tc 21:2ị Since the chip thickness after cutting is always greater than the corresponding thickness before cutting, the chip ratio will always be less than 1.0 In addition to to, the orthogonal cut has a width dimension w, as shown in Figure 21.6(a), even though this dimension does not contribute much to the analysis in orthogonal cutting The geometry of the orthogonal cutting model allows us to establish an important relationship between the chip thickness ratio, the rake angle, and the shear plane angle Let ls be the length of the shear plane We can make the substitutions: to ¼ ls sinf, and tc ¼ ls cos (f À a) Thus, r¼ ls sin f sin f ¼ ls cos (f À a) cos (f À a) This can be rearranged to determine f as follows: tan f ¼ r cos a À r sin a ð21:3Þ The shear strain that occurs along the shear plane can be estimated by examining Figure 21.7 Part (a) shows shear deformation approximated by a series of parallel plates sliding against one another to form the chip Consistent with our definition of shear strain E1C21 11/11/2009 490 15:44:2 Page 490 Chapter 21/Theory of Metal Machining FIGURE 21.7 Shear strain during chip formation: (a) chip formation depicted as a series of parallel plates sliding relative to each other; (b) one of the plates isolated to illustrate the definition of shear strain based on this parallel plate model; and (c) shear strain triangle used to derive Eq (21.4) (Section 3.1.4), each plate experiences the shear strain shown in Figure 21.7(b) Referring to part (c), this can be expressed as gẳ AC AD ỵ DC ẳ BD BD which can be reduced to the following definition of shear strain in metal cutting: g ¼ tan (f À a) þ cot f Example 21.1 Orthogonal Cutting ð21:4Þ In a machining operation that approximates orthogonal cutting, the cutting tool has a rake angle ¼ 10 The chip thickness before the cut to ¼ 0.50 mm and the chip thickness after the cut tc ¼ 1.125 in Calculate the shear plane angle and the shear strain in the operation Solution: The chip thickness ratio can be determined from Eq (21.2): r¼ 0:50 ¼ 0:444 1:125 The shear plane angle is given by Eq (21.3): tan f ¼ 0:444 cos 10 ¼ 0:4738 À 0:444 sin 10 f ¼ 25:4 E1C21 11/11/2009 15:44:2 Page 491 Section 21.2/Theory of Chip Formation in Metal Machining 491 Finally, the shear strain is calculated from Eq (21.4): g ẳ tan (25:4 10) ỵ cot 25:4 g ẳ 0:275 ỵ 2:111 ẳ 2:386 n 21.2.2 ACTUAL CHIP FORMATION We should note that there are differences between the orthogonal model and an actual machining process First, the shear deformation process does not occur along a plane, but within a zone If shearing were to take place across a plane of zero thickness, it would imply that the shearing action must occur instantaneously as it passes through the plane, rather than over some finite (although brief) time period For the material to behave in a realistic way, the shear deformation must occur within a thin shear zone This more realistic model of the shear deformation process in machining is illustrated in Figure 21.8 Metal-cutting experiments have indicated that the thickness of the shear zone is only a few thousandths of an inch Since the shear zone is so thin, there is not a great loss of accuracy in most cases by referring to it as a plane Second, in addition to shear deformation that occurs in the shear zone, another shearing action occurs in the chip after it has been formed This additional shear is referred to as secondary shear to distinguish it from primary shear Secondary shear results from friction between the chip and the tool as the chip slides along the rake face of the tool Its effect increases with increased friction between the tool and chip The primary and secondary shear zones can be seen in Figure 21.8 Third, formation of the chip depends on the type of material being machined and the cutting conditions of the operation Four basic types of chip can be distinguished, illustrated in Figure 21.9: å Discontinuous chip When relatively brittle materials (e.g., cast irons) are machined at low cutting speeds, the chips often form into separate segments (sometimes the segments are loosely attached) This tends to impart an irregular texture to the machined surface High tool–chip friction and large feed and depth of cut promote the formation of this chip type å Continuous chip When ductile work materials are cut at high speeds and relatively small feeds and depths, long continuous chips are formed A good surface finish typically results when this chip type is formed A sharp cutting edge on the tool and Chip FIGURE 21.8 More realistic view of chip formation, showing shear zone rather than shear plane Also shown is the secondary shear zone resulting from tool–chip friction Effective Tool Primary shear zone Secondary shear zone E1C21 11/11/2009 492 15:44:2 Page 492 Chapter 21/Theory of Metal Machining Discontinuous chip Continuous chip Continuous chip High shear strain zone Tool Tool Tool Low shear strain zone Tool Built-up edge Irregular surface due to chip discontinuities (a) Good finish typical (b) Particle of BUE on new surface (c) (d) FIGURE 21.9 Four types of chip formation in metal cutting: (a) discontinuous, (b) continuous, (c) continuous with built-up edge, (d) serrated low tool–chip friction encourage the formation of continuous chips Long, continuous chips (as in turning) can cause problems with regard to chip disposal and/or tangling about the tool To solve these problems, turning tools are often equipped with chip breakers (Section 23.3.1) å Continuous chip with built-up edge When machining ductile materials at low-tomedium cutting speeds, friction between tool and chip tends to cause portions of the work material to adhere to the rake face of the tool near the cutting edge This formation is called a built-up edge (BUE) The formation of a BUE is cyclical; it forms and grows, then becomes unstable and breaks off Much of the detached BUE is carried away with the chip, sometimes taking portions of the tool rake face with it, which reduces the life of the cutting tool Portions of the detached BUE that are not carried off with the chip become imbedded in the newly created work surface, causing the surface to become rough The preceding chip types were first classified by Ernst in the late 1930s [13] Since then, the available metals used in machining, cutting tool materials, and cutting speeds have all increased, and a fourth chip type has been identified: å Serrated chips (the term shear-localized is also used for this fourth chip type) These chips are semi-continuous in the sense that they possess a saw-tooth appearance that is produced by a cyclical chip formation of alternating high shear strain followed by low shear strain This fourth type of chip is most closely associated with certain difficult-to-machine metals such as titanium alloys, nickel-base superalloys, and austenitic stainless steels when they are machined at higher cutting speeds However, the phenomenon is also found with more common work metals (e.g., steels) when they are cut at high speeds [13].2 21.3 FORCE RELATIONSHIPS AND THE MERCHANT EQUATION Several forces can be defined relative to the orthogonal cutting model Based on these forces, shear stress, coefficient of friction, and certain other relationships can be defined A more complete description of the serrated chip type can be found in Trent & Wright [12], pp 348–367 E1BINDEX 11/09/2009 19:17:53 Page 1009 Index Plaster-mold casting, 235–236 Plastic deformation, 33 Plasticizers, 164, 171 Plastic pressing, 373 Plastics, see Polymers Platinum, 130–131 Pointing (drawing), 435 Point-to-point, 897 Polishing, 624 Polyamides, 168 Polybutadiene, 179 Polycarbonate, 169 Polydimethylsiloxane, 181 Polyesters, 169, 173–174 Polyethylene, 169–170 Polyethylene terephthalate, 169, 301 Polyimides, 174 Polyisoprene, 177–178, 180 Polymerization, 156–158 Polymer matrix composites: defined, 199, 327 materials, 199–201, 329–331 processing, 327–342 Polymer melts, 269–271 Polymers, 153–184 additives, 164–165 categories, 153–154 composites, 199–201 defined, 9, 153 hardness, 56 history, 154 polymerization, 156–158, 159 properties, 37–38, 56 rubbers, see Elastomers shape processing, 184, 268–308 structures, 159–161 thermal behavior, 163 thermoplastics, see Thermoplastics thermosets, see Thermosetting polymers Polymethylmethacrylate, 167, 863 Polyoxymethylene, 166 Polypropylene, 170, 301 Polystyrene, 170 Polytetrafluoroethylene, 168 Polyurethanes, 174, 180–181 Polyvinylchloride, 171, 301 Porcelain, 141 Porcelain enameling, 688 Positioning systems, 897, 898–902 Potter’s wheel, 373 Powder injection molding, 359–360, 378 Powder metallurgy, 99, 344–364 Powders, 347–352 Power: arc welding, 711–712 automation, 887 extrusion, 425 machining, 497–500 resistance welding, 720–721 rolling, 400–401 Power density (welding), 700–701 Precious metals, 130–131 Precipitation hardening: general, 661–662 stainless steel, 115 Precision, 80–81, 902–905 Precision forging, 411 Preform molding, 330, 336 Prepreg, 331, 332 Press: drill, 522–523 extrusion (metal), 426–428 forging, 405, 415 stamping, 15, 443, 466–470 Press-and-blow, 260 Press brake, 468 Press fit technology, 848 Press fitting, 774–776 Pressing: ceramics, 373, 377 glass, 260 powder metallurgy, 344, 354–355, 358–359 Pressure gas welding, 729 Pressure thermoforming, 303–304 Primary bonds, 28–29 Printed circuit board, 832–840 Printed circuit board assembly, 840–847 Process capability, 978–980 Process controller, 893–894 Process planning, 946–953 Processing operations, 10 Processes, manufacturing, classification of, history of, 11–12 shaping processes, Product design considerations: assembly, 779–782 casting, 253–254 ceramics, 380–381 glass, 266 machining, 597–599 plastics, 308–310 powder metallurgy, 362–364 rubber, 324–325 welding, 742–743 Products, manufactured, Production capacity, Production flow analysis, 931 Production line(s), 19, 920–931 Production planning and control, 959–973 Production quantity, 5–6, 17–19 Production system, 16–17 Programmable logic controller, 894 Properties: fluid, see Fluid properties mechanical, see Mechanical properties physical, see Physical properties Property-enhancing processes, 14 Protractor, 86 1009 Pseudoplastic, 60 Pulforming, 340–341 Pultrusion, 328, 339–340 Punch-and–die, 443 Punching, 445 Quality: casting, 249–251 defined, 977–978 programs, 984–990 weld, 738–742 Quality control, 977 Quantity, production, 18 Quantum mechanics, 875–876 Quartz, 140 Quenching, 660 Rack plating, 676 Radial drill, 522 Radial forging, 417 Rake angle, 486 Rapid prototyping, 786–797, 866–867 Rapid tool making, 796 Reaction injection molding, 295, 308, 337 Reaming, 513, 521 Recrystallization, 57, 389, 657 Recrystallization temperature, 57–58 Recycling: polymers, 182–183 glass, 259 Redrawing, 459 Reduction: bar drawing, 431 deep drawing, 458 extrusion, 423 rolling, 398 Reflow soldering, 757, 845–846 Refractory ceramics, 141 Refractory metals, 129–130 Reinforcing agents: in composites, 189–192, 199 in plastics, 164 Relief angle, 486 Rent’s rule, 821 Reorder point, 965 Repeatability, 904 Resin transfer molding, 336 Resistance projection welding, 724 Resistance welding, 695, 719–726 Resistivity, 74 Retaining ring, 777 Reverse drawing, 460 Reverse extrusion, 421 Rheocasting, 242 Rheology, 242 Rhodium, 131 Ring rolling, 403–404 Riser (casting), 209, 219–220, 248 Rivet(s), 773–774 Robotics, 697, 907–912 Rockwell hardness, 54 E1BINDEX 11/09/2009 1010 19:17:53 Page 1010 Index Roll bending, 472, 477 Roll coating, 762 Roll forging, 417–418 Roll forming, 472 Roll piercing, 404–405 Roll welding, 733–734 Roller mill, 370, 402–403 Rolling: gear, 404 glass, 262 metals, 385, 396–403 powdered metals, 360 ring, 403–404 thread, 403 Rolling mills, 15 Rotary tube piercing, 405 Rotational molding, 301–302 Roughing, 488 Roughness, surface, see Surface roughness Roundness, 80 Route sheet, 948–950 Rubber, see Elastomers Rule, steel, 81 Rule of mixtures, 193–194 Ruthenium, 131 Rutile, 127, 143 Sand blasting, 671 Sand casting, 225–230 Sandwich molding, 294 Sandwich structure, 196 Saw blade, 576 Sawing, 536–537 Scanning probe microscopes, 859, 876–877, 880–881 Scanning laser systems, 994–995 Scanning tunneling microscope, 876–877 Scheelite, 130 Scleroscope, 54–55 Screen printing, 836 Screen resist, 645 Screw(s), 767–769 Screw threads, 538–540 Screw thread inserts, 770 Seam welding, 723 Seaming, 779 Secondary bonds, 29–30 Segregation (in alloys), 101 Selective laser sintering, 794–795 Self-assembly, 881–883 Semicentrifugal casting, 244 Semiconductor, 75 Semi-dry pressing, 373–374 Semimetals, 26 Seminotching, 449 Semipermanent-mold casting, 237 Semi-metal casting, 242 Sensors, 890–891 Setup reduction, 970 Sewing, 778 Shape factor: extrusion (metal), 426–427 extrusion (plastic), 277 forging, 408 Shaping, 533–535 Shaping processes, 12 Sharkskin, 281 Shaving, 450 Shear modulus, 52 Shear plane, 488–490 Shear properties, 51–52 Shear spinning, 473–474 Shear strength, 52 Shearing, 386, 445 Sheet: metal, 443 metalworking, 385–386, 443–476 plastic, 281–283 Shell casting, 307 Shell molding, 230–231 Shielded metal arc welding, 712–713 Shop floor control, 971–973 Shot peening, 671 Shrink fit, 776 Shrinkage casting, 217–218 ceramics, 375 plastic molding, 292–293 Sialon, 144, 567 Siderite, 106 Silica, 136, 140, 145 Silicon, 150, 800 Silicon carbide, 9, 140, 141 Silicon nitride, 144 Silicon processing, 803, 805–809 Silicones, 174–175, 181 Siliconizing, 673 Silver, 130–131 Simultaneous engineering, 956 Sine bar, 86 Single-point tools, 486, 568–571 Sintering, 344, 355–356, 378, 379, 688 Sintered polycrystalline diamond, 567 Six sigma, 20, 985–988 Size effect, 499 Slide caliper, 82 Slip, 33–34 Slip casting, 371–372 Slit-die extrusion, 281 Slotting, 449 Slush casting, 237–238, 306–307 Smithsonite, 128 Snag grinder, 621 Snap fit, 776–777 Snap ring, 777 Soaking, 396, 657 Soft lithography, 864–865, 878 Solder paste, 845–846 Soldering, 754–758 Solid ground curing, 791–792 Solid solution, Solid-state electronics, 800 Solid-state welding, 696, 709, 732–738 Solidification time (casting), 216 Solidification processes, 12 Solidus, 69, 100, 215 Spade drill, 573–574 Spark sintering, 361 Specific energy (machining), 498 Specific gravity, 68 Specific heat, 70–71 Sphalerite, 128 Spinning: glass, 260 plastics, 284–285 sheet metal, 472–474 Spot facing, 522 Spot welding, 721–723 Spraying (coating), 687, 688 Spray–up, 333 Springback, 452 Sputtering, 681–682, 816 Squareness, 80 Squeeze casting, 242 Stainless steel, 114–116 Stamping, 443 Stapling, 778 Statistical process control, 980–984 Steel(s), defined, 105, 111 for casting, 251–252 high speed, see High speed steel low alloy, 113–114 plain carbon, 111–113 production of, 108–111 specialty, 117–118 stainless, 114–116 tool, 115–117 Stereolithography, 789–791, 867 Stick welding, 712 Sticking (friction), 392, 399 Stitching, 777–778 Straightness, 80 Strain: defined, 42, 44 metal machining, 489–490 Strain hardening, 46 Strain hardening exponent, 46–47, 386 Strain-rate, 389–391 Strain-rate sensitivity, 389–391 Strand casting, 111 Straightness, 80 Strength coefficient, 46–47, 386 Strength-to-weight ratio, 68 Stress-strain relationship: compression, 48–50 shear, 52 tensile, 40–48 Stretch bending, 477 Stretch blow molding, 300 Stretch forming, 471–472 Structural foam molding, 293 E1BINDEX 11/09/2009 19:17:53 Page 1011 Index Stud(s), 769 Stud welding, 719 Styrene-butadiene rubber, 181 Styrene-butadiene-styrene, 181 Submerged arc welding, 716–717 Super alloys, 131–132 Superconductor, 74–75 Supercooled liquid, 37, 69 Superfinishing, 623–624 Superheat, 211 Surface finish, see Surface roughness Surface grinding, 616–617 Surface hardening, 663–664 Surface integrity, 88, 91–92, 94 Surface micromachining, 861 Surface-mount technology, 821, 830, 843–847 Surface processing, 12, 15, 668–690, 761–762 Surface roughness casting, 253–254 defined, 89–90 grinding, 610–611 machining, 588–591 measurement of, 92–93 manufacturing processes, 94–95 Surface technology, 87 Surface texture, 88–89, 94 Surfaces, 87–94 Surfacing weld, 700 Sustainable manufacturing, 22 Swaging, 417 Synthetic rubber, 178–182, 316 Systems, production, 16–17 Taguchi methods, 988–989 Tantalum carbide, 143 Tape-laying machines, 334 Tapping, 521, 540 Taylor, Frederick, 3, 556, 560 Taylor tool life equation, 555–559 Technological processing capability, Technology (defined), Teflon, 168 Temperature effect on properties, 56–58 grinding, 612–613 machining, 500–501 metal forming, 387–389 Tempering: glass, 265 metal, 660 Tensile strength, 43, 771–772 Tensile test, 41 Terneplate, 678 Testing: electronic assemblies, 843, 847 hardness, 53–55 inspection, 991 integrated circuits, 823, 824 tensile properties, 41–47 torsion properties, 51–52 printed circuit boards, 839–840 welds, Thermal energy processes, 636–644 Thermal oxidation, 813 Thermal properties: conductivity, 70–72 diffusivity, 71 expansion, 36, 68–69 in manufacturing, 71–72 in metal cutting, 500 specific heat, 70 Thermal spraying, 689 Thermit welding, 731–732 Thermocompression bonding, 823 Thermoforming, 302–306, 308 Thermoplastic elastomers, 176, 181–182, 324 Thermoplastic polymers: composites, 329, defined, 9, 153 important thermoplastics, 166–171 properties, 38, 165–166 shaping processes, 268–308 Thermosetting polymers: composites, 329, defined, 9, 153 important thermosets, 172–175 properties, 38, 171–172 shaping processes, 268–308 Thermosonic bonding, 823 Thin-film magnetic heads, 856 Thixocasting, 242 Thixomolding, 242 Thixotropy, 242 Threaded fasteners, 767–773 Threading, 513, 538 Thread rolling, 403 Three-dimensional printing, 795 Three-plate mold, 289 Through-hole technology, 821 TIG welding, 717 Time-temperature-transformation curve, 658–659 Time, machining: drilling, 520–521 electrochemical machining, 634–635 milling, 527–528 minimizing, 592–594 turning, 87, 511 Tin, 129, 252 Tin-lead alloy system, 102–103, 129 Tinning, 678, 754 Tires, 321–323 Titanium, 126–127, 253 Titanium carbide, 143, 197 Titanium nitride, 144 Tolerance(s): casting, 254 defined, 78, 79 machining, 588 1011 manufacturing processes, 94 plastic molding, 310 Tool-chip thermocouple, 500 Tool grinders, 620 Tools, see Cutting tools or Dies Torque-turn tightening, 773 Torque wrench, 773 Torsion test, 51 Total quality management, 984–985 Total solidification time, 216–217 Transfer line, 927–928 Transfer molding, 297–298, 336 Transverse rupture strength, 50–51 Trimming, 248, 419, 450 True-stress-strain, 44–48 Truing, 614 TTT curve, 658–659 Tube drawing, 435–436 Tube rolling, 341 Tube sinking, 435 Tube spinning, 474 Tumbling, 671 Tungsten, 130, 562 Tungsten carbide: cutting tools, 563–566 general, 143, 197 history, 143 processing of, 143 Tunneling, 877 Turning, 12, 14, 485, 496–497, 510–519, 533 Turning center, 533 Turret drill, 522 Turret lathe, 516, 519 Turret press, 468 Twinning, 34–35 Twist drill, 571–572 Twisting, 463 Two-plate mold, 288–289 Two-roll mill, 317 Ultimate tensile strength, 43 Ultra-high precision machining, 866 Ultrasonic bonding, 823 Ultrasonic inspection, 998 Ultrasonic machining, 629–630, 866 Ultrasonic welding, 696, 737–738 Ultraviolet, 811, 812 Undercut, 646 Unilateral tolerance, 79 Unit cell, 30 Unit operation, 10 Upset forging, 406, 416 Upset welding, 725 Upsetting, 406, 416 Urea formaldehyde, 172 V-bending, 450–451 V-process, 231 Vacuum evaporation, 681, 816 Vacuum molding, 231–232 E1BINDEX 11/09/2009 1012 19:17:53 Page 1012 Index Vacuum permanent-mold casting, 238–239 Vacuum thermoforming, 302–303 Valence electrons, 27 Van der Waals forces, 29 Vanadium, 114 Vapor degreasing, 670 Vernier caliper, 82 Vibratory finishing, 672 Vickers hardness, 54 Viscoelasticity, 60–62 Viscosity, 58–60 Vision, machine, 995–997 Volumetric specific heat, 71 Vulcanization, 12, 176, 177, 320 Wafer, silicon, 807–809, 823 Warm working, 388 Washer, 770–771 Water atomization, 351 Water jet cutting, 630–631 Wave soldering, 757, 844–845 Waviness (in surface texture), Wear: cutting tool, 552–556 grinding wheel, 613–614 Weldability, 742 Weldbonding, 759 Weld joints, 697–698 Welding, defects, 739–741 definition and overview, 693–697 design considerations, 742–743 history, 694–695 joints, 697–700, 704–705 physics, 700–704 processes, 695–696, 709–738 quality, 738–742 Wet chemical etching, 817 Wet lay-up, 332 Wet spinning, 285 Whiskers, 190 White cast iron, 119 Whitney, Eli, Wire and cable coating, 280 Wire bonding, 823 Wire drawing, 385, 430–435 Wire EDM, 639 Wolframite, 143 Work content time, 924 Work hardening, 46 Work holding, drilling, 522–523 turning, 514–516 Wrought metal, 99 X-ray inspection, 998 X-ray lithography, 812, 878 Yield point, 43 Yields, 824–825 Yield strength, 43 Zinc, 128–129, 252 E1ENDPAPER 11/03/2009 16:10:6 Page STANDARD UNITS USED IN THIS BOOK Units for both the System International (SI, metric) and United States Customary System (USCS) are listed in equations and tables throughout this textbook Metric units are listed as the primary units and USCS units are given in parentheses Prefixes for SI units: Prefix Symbol Multiplier nanomicromillicentikilomegagiga- n m m c k M G 10À9 10À6 10À3 10À2 103 106 109 Example units (and symbols) nanometer (nm) micrometer, micron (mm) millimeter (mm) centimeter (cm) kilometer (km) megaPascal (MPa) gigaPascal (GPa) Table of Equivalencies between USCS and SI units: Variable SI units USCS units Equivalencies 1.0 in ¼ 25.4 mm ¼ 0.0254 m 1.0 ft ¼ 12.0 in ¼ 0.3048 m ¼ 304.8 mm 1.0 yard ¼ 3.0 ft ¼ 0.9144 m ¼ 914.4 mm 1.0 mile ¼ 5280 ft ¼ 1609.34 m ¼ 1.60934 km 1.0 m-in ¼ 1.0  10À6 in ¼ 25.4  10À3mm 1.0 in2 ¼ 645.16 mm2 1.0 ft2 ¼ 144 in2 ¼ 92.90  10À3 m2 1.0 in3 ¼ 16,387 mm3 1.0 ft2 ¼ 1728 in3 ¼ 2.8317  10À2 m3 1.0 lb ¼ 0.4536 kg 1.0 ton (short) ¼ 2,000 lb ¼ 907.2 kg 1.0 lb/in3 ¼ 27.68  103 kg/m3 1.0 lb/ft3 ¼ 16.0184 kg/m3 1.0 ft/min ¼ 0.3048 m/min ¼ 5.08  10À3 m/s 1.0 in/min ¼ 25.4 mm/min ¼ 0.42333 mm/s 1.0 ft/sec ¼ 0.3048 m/s2 1.0 lb ¼ 4.4482 N 1.0 ft-lb ¼ 12.0 in-lb ¼ 1.356 N-m 1.0 in-lb ¼ 0.113 N-m 1.0 lb/in2 ¼ 6895 N/m2 ¼ 6895 Pa 1.0 lb/in2 ¼ 6.895  10À3 N/mm2 ¼ 6.895  10À3 MPa Length meter (m) Area m2, mm2 inch (in) foot (ft) yard mile micro-inch (m-in) in2, ft2 Volume m3, mm3 in3, ft3 Mass kilogram (kg) Density kg/m3 Velocity Acceleration Force Torque m/min m/s m/s2 Newton (N) N-m pound (lb) ton lb/in3 lb/ft3 ft/min in/min ft/sec2 pound (lb) ft-lb, in-lb Pressure Stress Pascal (Pa) Pascal (Pa) lb/in2 lb/in2 Energy, work Joule (J) ft-lb, in-lb Heat energy Power Joule (J) Watt (W) British thermal unit (Btu) Horsepower (hp) Specific heat Thermal conductivity Thermal expansion Viscosity J/kg- C J/s-mm- C Btu/lb- F Btu/hr-in - F 1.0 ft-lb ¼ 1.356 N-m ¼ 1.356 J 1.0 in-lb ¼ 0.113 N-m ¼ 0.113 J 1.0 Btu ¼ 1055 J 1.0 hp ¼ 33,000 ft-lb/min ¼ 745.7 J/s ¼ 745.7 W 1.0 ft-lb/min ¼ 2.2597  10À2 J/s ¼ 2.2597  10À2 W 1.0 Btu/lb- F ¼ 1.0 Calorie/g- C ¼ 4,187 J/kg- C 1.0 Btu/hr-in - F ¼ 2.077  10À2 J/s-mm- C (mm/mm)/ C (in/in)/ F 1.0 (in/in)/ F ¼ 1.8 (mm/mm)/ C Pa-s lb-sec/in2 1.0 lb-sec/in2 ¼ 6895 Pa-s ¼ 6895 N-s/m2 E1ENDPAPER 11/03/2009 16:10:6 Page 10 CONVERSION BETWEEN USCS AND SI To convert from USCS to SI: To convert the value of a variable from USCS units to equivalent SI units, multiply the value to be converted by the right-hand side of the corresponding equivalency statement in the Table of Equivalencies Example: Convert a length L ¼ 3.25 in to its equivalent value in millimeters Solution: The corresponding equivalency statement is: 1.0 in ¼ 25.4 mm L ¼ 3:25 in  (25:4 mm/in) ¼ 82:55 mm To convert from SI to USCS: To convert the value of a variable from SI units to equivalent USCS units, divide the value to n be converted by the right-hand side of the corresponding equivalency statement in the Table of Equivalencies Example: Convert an area A ¼ 1000 mm2 to its equivalent in square inches Solution: The corresponding equivalency statement is: 1.0 in2 ¼ 645.16 mm2 A ¼ 1000 mm2 /(645:16 mm2 /in2 ) ¼ 1:55 in2 n ... Machines 22 .3 Drilling and Related Operations 22 .3.1 Cutting Conditions in Drilling 22 .3 .2 Operations Related to Drilling 22 .3.3 Drill Presses 22 .4 Milling 22 .4.1 Types of Milling Operations 22 .4 .2. .. speed that is in the form of the Trigger equation, Eq (21 .23 ) E1C 22 10 /26 /20 09 15 :27 :25 Page 507 22 MACHINING OPERATIONS AND MACHINE TOOLS Chapter Contents 22 .1 Machining and Part Geometry 22 .2. .. Milling 22 .4.3 Milling Machines 22 .5 Machining Centers and Turning Centers 22 .6 Other Machining Operations 22 .6.1 Shaping and Planing 22 .6 .2 Broaching 22 .6.3 Sawing 22 .7 Machining Operations for Special