İmal Usulleri toz metalurjisi ( ingilzice ) Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 P/M Parts Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 FIGURE 11.1 (a) Examples of typical parts made by powder-metallurgy processes. (b) Upper trip lever for a commercial irrigation sprinkler, made by P/M. Made of unleaded brass alloy, it replaces a die-cast part, at a 60% cost savings. Source: Courtesy of Metal Powder Industries Federation. (a) (b)Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Particle Shapes FIGURE 11.2 Particle shapes and characteristics of metal powders and the processes by which they are produced. (a) One-dimensional (b) Two-dimensional Acicular (chemical decomposition) Irregular rodlike (chemical decomposition, mechanical comminution) Flake (mechanical comminution) Dendritic (electrolytic) (c) Three-dimensional Spherical (atomization, carbonyl (Fe), precipitation from a liquid) Irregular (atomization, chemical decomposition) Angular (mechanical disintegration, carbonyl (Ni )) Rounded (atomization, chemical decomposition) Porous (reduction of oxides)Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Powder Production FIGURE 11.3 Methods of metal-powder production by atomization: (a) gas atomization; (b) water atomization; (c) atomization with a rotating consumable electrode; and (d) centrifugal atomization with a spinning disk or cup. Vacuum Spindle Inert gas Rotating consumable electrode Nonrotating tungsten electrode Collection port (b) Atomizing gas spray Molten metal Metal particles (a) (c) (d) Tundish High-pressure water manifold Atomization tank Water atomization Dewatering Liquid metal Metal particles Spinning disk Tundish Atomizing chamber Ladle Molten metal Ladle TundishManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Particle Size Distribution FIGURE 11.4 (a) Distribution of particle size, given as weight percentage; note that the highest percentage of particles have a size between 75 and 90 µm. (b) Cumulative particle-size distribution as a function of weight. Source: After R.M. German. 20 15 10 5 0 Weight (%) 10 100 1000 Particle size (µm) 100 75 50 25 0 Cumulative weight finer (%) Particle size (µm) 10 100 1000 (a) (b)Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Compaction FIGURE 11.5 (a) Compaction of metal powder to produce a bushing. (b) A typical tool and die set for compacting a spur gear. Source: Courtesy of Metal Powder Industries Federation. Compacted shape (green) Upper punch Lower punch Powder Feed Shoe (b) Ejector Lower punch P/M spur gear (green) Core rod Upper punch (a) Die 1. 2. 3. 4. DieManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Density vs. Compacting Pressure FIGURE 11.6 (a) Density of copper- and iron-powder compacts as a function of compacting pressure. Density greatly in?uences the mechanical and physical properties of P/M parts. Source: After F .V. Lenel. (b) Effect of density on tensile strength, elongation, and electrical conductivity of copper powder. (IACS is International Annealed Copper Standard for electrical conductivity.) Elongation Conductivity Tensile strength lb/in 3 0.29 0.30 0.31 0.32 30 25 20 15 10 psi x 10 3 Tensile strength (MPa) Elongation (%) Electrical conductivity (% IACS) 200 150 100 (b) 40 35 30 25 20 100 95 90 85 80 Sintered density (g/cm 3 ) 8.0 8.2 8.4 8.6 8.8 Apparent Density Density of iron Density of copper 0 200 400 600 800 1000 1200 MPa 0 1 2 3 4 5 6 7 8 9 Density (g/cm 3 ) 0 20 40 60 80 100 Compacting pressure (tons/in 2 ) 0 0.3 0.2 0.1 lb/in 3 (a) Copper powder, coarse 3.49 g/cm 3 Iron powder, fine 1.40 Iron powder, coarse 2.75 Copper powder, fine 1.44Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Mechanics of Compaction FIGURE 11.8 Coordinate system and stresses acting on an element in compaction of powders. The pressure is assumed to be uniform across the cross-section. (See also Fig. 6.4.) (a) (b) (c) (d) (e) L/D = 1.66 700 MPa 600 500 400 300 200 100 D/ 2 C L L FIGURE 11.7 Density variation in compacting metal powders in different dies: (a) and (c) single- action press; (b) and (d) double-action press, where the punches have separate movements. Note the greater uniformity of density in (d) as compared with (c). Generally, uniformity of density is preferred, although there are situations in which density variation, and hence variation of properties, within a part may be desirable. (e) Pressure contours in compacted copper powder in a single-action press. Source: After P . Duwez and L. Zwell. p 0 L x dx D p x p x + dp x µ r r Resultant pressure distribution: p x =p o e -4µkx/DManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Cold Isostatic Pressing FIGURE 11.9 Schematic illustration of cold isostatic pressing in compaction of a tube. (a) The wet-bag process, where the rubber mold is inserted into a ?uid that is subsequently pressurized. In the arrangement shown, the powder is enclosed in a ?exible container around a solid core rod. (b) The dry bag process, where the rubber mold does not contact the ?uid, but instead is pressurized through a diaphragm. Source: After R.M. German. (a) (b) Cover Fluid Mold seal plate Rubber mold (bag) Powder Metal mandrel Pressure vessel Wire mesh basket Pressure source Upper cover Fluid Powder Pressure vessel Pressing rubber mold Rubber diaphragm Forming rubber mold Lower inside cover Lower outside cover Pressure sourceManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Pressures and Capabilities FIGURE 11.10 Process capabilities of part size and shape complexity for various P/M operations; P/F is powder forging. Source: Metal Powder Industries Federation. 6 5 4 3 2 1 0 Relative shape complexity in. 30 20 10 0.2 0.4 0.6 HIP CIP P/M PIM Size (m) 0 P/F 0 Pressure MPa psi×10 3 Metal Aluminum 70–275 10–40 Brass 400–700 60–100 Bronze 200–275 30–40 Iron 350–800 50–120 Tantalum 70–140 10–20 Tungsten 70–140 10–20 Other Materials Auminum oxide 110–140 16–20 Carbon 140–165 20–24 Cemented carbides 140–400 20–60 Ferrites 110–165 16–24 TABLE 11.1 Compacting Pressures for Various Metal PowdersManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Hot Isostatic Pressing FIGURE 11.11 Schematic illustration of the sequence of steps in hot isostatic pressing. Diagram (4) shows the pressure and temperature variation versus time. Part Pressure Temperature Time Gas inlet End cap High-pressure cylinder Insulation Workpiece Heating coils End cap 1. Fill can 2. Vacuum bakeout 3. Hot isostatic press 4. Remove canManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Powder Rolling FIGURE 11.12 An example of powder rolling. The purpose of direction baf?es in the hopper is to ensure uniform distribution of powder across the width of the strip. Hopper Powder Direction baffles Shaping rolls Metal powder supply Green sheet Sintering furnace Hot rolls Cooling CoilerManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Spray Casting FIGURE 11.13 Spray casting (Osprey process) in which molten metal is sprayed over a rotating mandrel to produce seamless tubing and pipe. Tube Particle injector (optional) Induction-heated ladle Atomizer (nitrogen gas) Recipient substrate Deposition chamber Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Sintering TABLE 11.2 Sintering temperature and time for various metal powders. (a) 1. 1. 2. 2. 3. 3. (b) Neck formation by diffusion Distance between particle centers decreased, particles bonded Neck formation by vapor-phase material transport Particles bonded, no shrinkage (center distances constant) r R Material Temperature ( ? C) Time (min) Copper, brass, and bronze 760–900 10–45 Iron and iron graphite 1000–1150 8–45 Nickel 1000–1150 30–45 Stainless steels 1100–1290 30–60 Alnico alloys (for permanent magnets) 1200–1300 120–150 Ferrites 1200–1500 10–600 Tungsten carbide 1430–1500 20–30 Molybdenum 2050 120 Tungsten 2350 480 Tantalum 2400 480 FIGURE 11.14 Schematic illustration of two basic mechanisms in sintering metal powders: (a) solid-state material transport and (b) liquid-phase material transport. R=particle radius, r=neck radius, and =neck pro?le radius. ?Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Effect of T emperature and Time FIGURE 11.5 Effect of sintering temperature and time on (a) elongation and (b) dimensional change during sintering of type 316L stainless steel. Source: ASM International. Elongation (%) 40 30 20 10 0 0 30 60 90 120 150 Sintering time (min) 1315°C (2400°F) 1230°C (2250°F) 1120°C (2050°F) 0 20.4 20.8 21.2 21.6 Dimensional change from die size (%) 0 30 60 90 120 150 Sintering time (min) 1120°C (2050°F) 1230°C (2250°F) 1315°C (2400°F) (a) (b)Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Mechanical Properties of P/M Materials TABLE 11.3 Typical mechanical properties of selected P/M materials. Ultimate Tensile Yield Elongation Elastic MPIF Strength Strength in 25 mm Modulus Designation type Condition (MPa) (MPa) Hardness (%) (GPa) Ferrous FC-0208 N AS 225 205 45 HRB < 0.5 70 HT 295 – 95 HRB < 0.5 70 R AS 415 330 70 HRB 1 110 HT 550 – 35 HRC < 0.5 110 S AS 550 395 80 HRB 1.5 130 HT 690 655 40 HRC < 0.5 130 FN-0405 S AS 425 240 72 HRB 4.5 145 HT 1060 880 39 HRC 1 145 T AS 510 295 80 HRB 6 160 HT 1240 1060 44 HRC 1.5 160 Aluminum 601 AB AS 110 48 60 HRH 6 – pressed bar HT 252 241 75 HRH 2 – Brass CZP-0220 T – 165 76 55 HRH 13 – U – 193 89 68 HRH 19 – W – 221 103 75 HRH 23 – Titanium Ti-6AI-4V HIP 917 827 – 13 – Superalloys Stellite 19 – 1035 – 49 HRC < 1 – Note: MPIF=Metal Powder Industries Federation; AS=as sintered; HT=heat treated; HIP=hot isostatically pressed.Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Titanium Property Comparison TABLE 11.4 Mechanical property comparison for Ti-6Al-4V titanium alloy. Density Yield Stress Ultimate Tensile Elongation Reduction of Process (%) (MPa) Strength (MPa) (%) Area (%) Cast 100 840 930 7 15 Cast and forged 100 875 965 14 40 Powder metallurgy Blended elemental (P+S) * 98 786 875 8 14 Blended elemental (HIP) * > 99 875 9 17 Realloyed (HIP) 100 880 975 14 26 * P+S=pressed and sintered; HIP=hot isostatically pressed. Source: After R.M. GermanManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 P/M Example: Bearing Caps FIGURE 11.16 Powder-metal main bearing caps for 3.8- and 3.1-liter General Motors engines. Source: Courtesy of Zenith Sintered Products, Inc., Milwaukee, WI.Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Geometry for P/M Dies FIGURE 11.17 Die geometry and design features for powder-metal compaction. Source: Metal Powder Industries Federation. Workpiece Die 2°–3° taper to assist ejection 0.25–0.50 mm parallel surface to prevent punch jamming Step requires up to 12° taper to assist ejection Maximum feasible taper is 15° when bottom compaction is employed Upper punch 0.12–0.25 mm parallel surface to prevent powder capture in die 0.25–0.50 mm step to prevent powder capture in die Lower punch Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Design Considerations FIGURE 11.18 Examples of P/M parts, showing various poor and good designs. Note that sharp radii and reentry corners should be avoided, and that threads and transverse holes have to be produced separately, by additional operations such as machining or grinding. Source: Metal Powder Industries Federation. (b) (c) (d) Good Poor (f) (a) (e) Poor Good (g) (h) Sharp radius Fillet radius Must be machined Can be molded Sharp radius Fillet radius Upper punch Die Workpiece Feather edge required on punch 0.25 mm (0.010 in.) (min) Flat Acceptable, with additional operations Hole must be drilled Thread must be machined Best Acceptable Sharp radius Sharp radius Fillet radius Fillet radius Max 30 Workpiece Punch Die 30°–45° 0.25 mm (0.010 in.) (min)Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Design Considerations FIGURE 11.19 (a) Design features for use with unsupported ?anges. (b) Design features for use with grooves. Source: Metal Powder Industries Federation. (a) (b) Thin section Thicker flange Radius to reduce likelihood of chipping Radius for ease of ejection Taper to assist ejection Poor Good r H H 0.2H (max) up to 12° r 0.15H (max) Poor Good FIGURE 11.20 The use of abrupt transitions in molds for powder injection molding causing non-uniform metal-powder distribution within a part. Excessive binder Flow direction Excessive binder Powder build-up MoldManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Process Comparison TABLE 11.5 Competitive features of P/M and some other manufacturing processes. Process Advantages Over P/M Limitations as Compared With P/M Casting Wide range of part shapes and sizes produced; generally low mold and setup cost. Some waste of material in processing; some ?nishing required; may not be feasible for some high-temperature al- loys. Forging (hot) High production rate of a wide range of part sizes and shapes; high me- chanical properties through control of grain ?ow. Some ?nishing required; some waste of material in processing; die wear; relatively poor surface ?nish and di- mensional control. Extrusion (hot) High production rate of long parts; complex cross-sections may be pro- duced. Only a constant cross-sectional shape can be produced; die wear; poor di- mensional control. Machining Wide range of part shapes and sizes; short lead time; ?exibility; good di- mensional control and surface ?nish; simple tooling. Waste of material in the form of chips; relatively low productivity.Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Types of Ceramics and Glasses TABLE 11.6 Types and general characteristics of ceramics and glasses. Type General Characteristics Oxide Ceramics Alumina High hot hardness and abrasion resistance, moderate strength and toughness; most widely used ceramic; used for cutting tools, abrasives, and electrical and thermal insulation. Zirconia High strength and toughness; resistance to thermal shock, wear, and corrosion; partially-stabilized zirconia and transformation-toughened zirconia have better properties; suitable for heat-engine components. Carbides Tungsten carbide High hardness, strength, toughness, and wear resistance, depending on cobalt binder content; commonly used for dies and cutting tools. Titanium carbide Not as tough as tungsten carbide, but has a higher wear resistance; has nickel and molybdenum as the binder; used as cutting tools. Silicon carbide High-temperature strength and wear resistance, used for engines components and as abrasives. Nitrides Cubic boron nitride Second hardest substance known, after diamond; high resistance to oxidation; used as abrasives and cutting tools. Titanium nitride Used as coatings on tools, because of its low friction characteristics. Silicon nitride High resistance to creep and thermal shock; high toughness and hot hardness; used in heat engines. Sialon Consists of silicon nitrides and other oxides and carbides; used as cutting tools. Cermets Consist of oxides, carbides, and nitrides; high chemical resistance but is somewhat brittle and costly; used in high-temperature applications. Nanophase ceramics Stronger and easier to fabricate and machine than conventional ceramics; used in automotive and jet-engine applications. Silica High temperature resistance; quartz exhibits piezoelectric e?ects; silicates contain- ing various oxides are used in high-temperature, nonstructural applications. Glasses Contain at least 50% silica; amorphous structure; several types available, with a wide range of mechanical, physical, and optical properties. Glass ceramics High crystalline component to their structure; stronger than glass; good thermal- shock resistance; used for cookware, heat exchangers, and electronics. Graphite Crystalline form of carbon; high electrical and thermal conductivity; good thermal- shock resistance; also available as ?bers, foam, and buckyballs for solid lubrication; used for molds and high-temperature components. Diamond Hardest substance known; available as single-crystal or polycrystalline form; used as cutting tools and abrasives and as die insert for ?ne wire drawing; also used as coatings.Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Ceramic Structure FIGURE 11.21 The crystal structure of kaolinite, commonly known as clay; compare with Figs. 3.2-3.4 for metals. Oxygen ions Aluminum ions OH ions Silicon ionsManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Properties of Ceramics Transverse Rupture Compressive Elastic Poisson’s Strength Strength Modulus Hardness Ratio Density Material Symbol (MPa) (MPa) (GPa) (HK) (?) (kg/m 3 ) Aluminum oxide Al 2 O 3 140–240 1000–2900 310–410 2000–3000 0.26 4000–4500 Cubic boron nitride cBN 725 7000 850 4000–5000 – 3480 Diamond – 1400 7000 830–1000 7000–8000 – 3500 Silica, fused SiO 2 – 1300 70 550 0.25 – Silicon carbide SiC 100–750 700–3500 240–480 2100–3000 0.14 3100 Silicon nitride Si 3 N 4 480–600 – 300–310 2000–2500 0.24 3300 Titanium carbide TiC 1400–1900 3100–3850 310–410 1800–3200 – 5500–5800 Tungsten carbide WC 1030–2600 4100–5900 520–700 1800–2400 – 10,000–15,000 Partially stabilized zirconia PSZ 620 – 200 1100 0.3 5800 Note: These properties vary widely, depending on the condition of the material. TABLE 11.7 Approximate range of properties of various ceramics at room temperature. Strength: Elastic modulus: Thermal conductivity: UTS?UTS o e -nP E?E o (1-1.9P+0.9P 2 ) k =k o (1-P)Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 T emperature Effects FIGURE 11.22 Effect of temperature on thermal expansion for several ceramics, metals, and plastics. Note that the expansions for cast iron and for partially stabilized zirconia (PSZ) are within about 20%. 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 20.2 400 800 1200 1600 2000 2400 2800 3200 °F 200 400 600 800 1000 1200 1400 1600 Temperature (°C) Linear thermal expansion (%) Polyethylene Nylon Al alloys Cast iron and MgO Ni-base superalloy Partially stabilized ZrO 2 Al 2 O 3 ZrSiO 4 (zircon) SiC Lithium aluminum silicate Fused SiO 2 Si 3 N 4 600 500 400 300 200 100 0 Tensile strength (MPa) 0 200 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 °F 90 80 70 60 50 40 30 20 10 0 psi x 10 3 High-purity silicon nitride (Fine grain) High-purity silicon nitride Al 2 O 3 High-purity SiC SiC Sialon 116 Silicon nitride (reaction bonded) Glass ceramic Low-density SiC Temperature (°C) FIGURE 11.23 Effect of temperature on the strength of various engineering ceramics. Note that much of the strength is maintained at high temperatures; compare with Figs. 2.9 and 8.30. 800 1600 2400 °F GPa 400 300 200 100 0 60 50 40 30 20 10 0 Modulus of elasticity (psi x 10 6 ) SiC SrO 2 MgAl 2 O 4 TiC Al 2 O 3 Si 3 N 4 MgO ThO 2 0 400 800 1200 1600 Temperature (°C) FIGURE 11.24 Effect of temperature on the modulus of elasticity for various ceramics; compare with Fig. 2.9. Source: After D.W. Richerson.Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Example: Ceramic Bearings FIGURE 11.25 A selection of ceramic bearings and races. Source: Courtesy of Timken, Inc. (a) (b)Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Processes & Particle Production TABLE 11.8 General characteristics of ceramics processing methods. (a) (b) (c) Process Advantages Limitations Slip casting Large parts; complex shapes; low equip- ment cost. Low production rate; limited dimensional accuracy. Extrusion Hollow shapes and small diameters; high production rate. Parts have constant cross-section; limited thickness. Dry pressing Close tolerances; high production rate with automation. Density variation in parts with high length-to-diameter ratios; dies require high abrasive-wear resistance; equipment can be costly. Wet pressing Complex shapes; high production rate. Limited part size and dimensional accu- racy; tooling costs can be high. Hot pressing Strong, high-density parts. Protective atmospheres required; die life can be short. Isostatic pressing Uniform density distribution. Equipment can be costly. Jiggering High production rate with automation; low tooling cost. Limited to axisymmetric parts; limited di- mensional accuracy. Injection molding Complex shapes; high production rate. Tooling costs can be high. FIGURE 11.26 Methods of crushing ceramics to obtain very ?ne particles: (a) roll crushing, (b) ball milling, and (c) hammer milling.Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Slip Casting FIGURE 11.27 Sequence of operations in slip casting a ceramic part. After the slip has been poured, the part is dried and ?red in an oven to give it strength and hardness. The step in (d) is a trimming operation. Source: After F .H. Norton. (a) (b) (c) (d) Trimming knife (e) Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Doctor-Blade Process FIGURE 11.28 Production of ceramic sheets through the doctor-blade process. Take-up spool Ceramic tape on carrier tape Carrier film Air (filtered) in Exhaust out Slurry chamber and doctor blade Drying chamber Doctor blade Controller for take-up spool Ceramic slurry Ceramic film Carrier film Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Density Variation in Compacts FIGURE 11.29 Density variation in pressed compacts in a single-action press. Note that the variation increases with increasing L/D ratio; see also Fig. 11.7e. Source: After W.D. Kingery. 10 20 40 54 50 65 90 100 L D Punch Punch Die L D = 1.75Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Extruding and Joggering FIGURE 11.30 (a) Extruding and (b) jiggering operations in shaping ceramics. Source: After R.F . Stoops. (b) (a) Mold return Deairing chamber Clay slug Bat former Jigger tool Water Formed ware Extruder To vacuum FIGURE 11.31 Shrinkage of wet clay, caused by removal of water during drying; shrinkage may be as much as 20% by volume. Source: After F .H. Norton. Interparticle water Clay particles Dry Pore water (a) (b) (c) Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Glasses Soda-lime Lead Borosilicate Fused 96% Silica Glass Glass Glass Glass Density High Highest Medium Low Lowest Strength Low Low Moderate High Highest Resistance to thermal shock Low Low Good Better Best Electrical resistivity Moderate Best Good Good Good Hot workability Good Best Fair Poor Poorest Heat treatability Good Good Poor None None Chemicals resistance Poor Fair Good Better Best Impact abrasion resistance Fair Poor Good Good Best Ultraviolet-light transmission Poor Poor Fair Good Good Relative cost Lowest Low Medium High Highest TABLE 11.9 General characteristics of various types of glasses.Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Glass Sheet & T ubing FIGURE 11.32 The ?oat method of forming sheet glass. Source: Corning Glass Works. Controlled atmosphere furnace Furnace Float bath Lehr Rollers Molten tin FIGURE 11.33 Continuous manufacturing process for glass tubing. Air is blown through the mandrel to keep the tube from collapsing. Source: Corning Glass Works. Tube Molten glass Mandrel RollersManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Glass Bottles FIGURE 11.34 Stages in manufacturing a common glass bottle. Source: After F .H. Norton. Gob 2. Gob in blank mold Blank mold Neck ring Tip 1. Gob falling into blank mold 3. Blow down in blank mold Blow head Baffle Air Air 4. Blow back in blank mold Air 5. Blank mold reversed 6. Parison hanging on neck ring, reheated during transfer 8. Bottle blown, cooling 7. Parison in blow mold Blow mold Parison Tongs 9. Finished bottle removed by tongsManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Glass Pressing FIGURE 11.35 Manufacturing steps for a glass item by pressing in a mold. Source: Corning Glass Works. 1. Empty mold 2. Loaded mold 3. Glass pressed 4. Finished piece FIGURE 11.36 Pressing glass in a split mold. Note that the use of a split mold is essential to be able to remove the part; see also Figs. 10.34, 10.35, and 10.36. Source: After E.B. Shand. 3. Glass pressed 2. Loaded mold 1. Empty mold 4. Finished product Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Residual Stresses in Glass FIGURE 11.37 Stages in the development of residual stresses in tempered glass plate. Residual stresses (b) (a) Compression Tension 1. Hot glass, no stresses. 2. Surface cools quickly, surface contracts, center adjusts, only minor stresses. 3. Center cools, center contracts, surface is compressed, center in tension. Thickness Step 1 Step 2 Step 3 Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Metal-Matrix Composites Fiber Matrix Typical Applications Graphite Aluminum Satellite, missile, and helicopter structures Magnesium Space and satellite structures Lead Storage-battery plates Copper Electrical contacts and bearings Boron Aluminum Compressor blades and structural supports Magnesium Antenna structures Titanium Jet-engine fan blades Alumina Aluminum Superconductor restraints in fusion power reactors Lead Storage-battery plates Magnesium Helicopter transmission structures Silicon carbide Aluminum, titanium High-temperature structures Superalloy (cobalt base) High-temperature engine components Molybdenum, tungsten Superalloy High-temperature engine components TABLE 11.10 Metal-matrix composite materials and typical applications.Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Example: Brake Caliper FIGURE 11.38 Aluminum-matrix composite brake caliper, using nanocrystalline alumina-?ber reinforcement. Source: Courtesy of 3M Specialty Materials Division.Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Powder-in-Tube Process FIGURE 11.39 Schematic illustration of the steps involved in the powder-in-tube process. Source: Courtesy of Concurrent T echnologies Corporation. Superconducting ceramic powder 1. Fill 2. Pack High-purity silver tube 3. Extrude/Draw Wire 4. Roll Strip HopperManufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid © 2008, Pearson Education ISBN No. 0-13-227271-7 Case Study: Engine Valves FIGURE 11.40 A valve lifter for heavy-duty diesel engines, produced from a hot-isostatically-pressed carbide cap on a steel shaft. Source: Courtesy of Metal Powder Industries Federation and Bodycote, Inc. Steel shaft Steel cap Copper interlayer Tungsten-carbide wear face