Ch40

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CHAPTER 40

Competitive Aspects of Manufacturing

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Commercially Available Materials

TABLE 40.1Material Available asAluminumCopper and brassMagnesiumSteels and stainless steelsPrecious metalsZincPlasticsElastomersCeramics (alumina)GlassGraphite

P, F, B, T, W, S, IP, f, B, T, W, s, IP, B, T, w, S, IP, B, T, W, S, IP, F, B, t, W, IP, F, D, W, IP, f, B, T, wP, b, Tp, B, T, sP, B, T, W, sP, B, T, W, s

Note: P, plate or sheet; F, foil; B, bar; T, tubing; W, wire; S,structural shapes; I, ingots for casting. Lowercase letter indicates limited availability. Most of these materials are alsoavailable in powder form.

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Approximate Amount of Scrap Produced inVarious Manufacturing Processes

TABLE 40.2

ProcessScrap(%) Process

Scrap(%)

Machining 10–60 Cold or hot extrusion, forging 15Hot closed-die forging 20–25 Permanent-mold casting 10Sheet-metal forming 10–25 Powder metallurgy 5Rolling, ring rolling <1

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Advanced Materials

Figure 40.1 Advancedmaterials used on the LockheedC-5A transport aircraft. (FRP:fiber-reinforced plastic)

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Material Changes From C-5A to C-5B MilitaryCargo Aircraft

TABLE 40.3Item C-5A Material C-5B Material Reason for changeWing panels 7075–T6511 7175–T73511 DurabilityMain frame Forgings 7075–F 7049–01 Stress corrosion resistance Machined frames 7075–T6 7049–T73 Frame straps 7075–T6 plate 7050–T7651 plateFuselage skin 7079–T6 7475–T61 Material availabilityFuselage underfloor endfittings

7075–T6 forging 7049–T73 forging Stress corrosion resistance

Wing/pylon attach fitting 4340 alloy steel PH13–8Mo Corrosion preventionAft ramp lock hooks D6–AC PH13–8Mo Corrosion preventionHydraulic lines AM350 stainless steel 21–6–9 stainless steel Improved field repairFuselage failsafe straps 6AI–4V titanium 7475–T61 aluminum Titanium strap debond

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Methods of Making a Simple Part

Figure 40.2 Various methods of making a simple part: (a) casting or powder metallurgy,(b) forging or upsetting, (c) extrusion, (d) machining, (e) joining two pieces.

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Manufacturing Process Capabilities

Figure 40.3Manufacturingprocess capabilitiesfor minimum partdimensions. Source:J. A. Schey,Introduction toManufacturingProcesses (2d ed.).McGraw-Hill, 1987.

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Dimensional Tolerance

Figure 40.4Dimensional tolerancecapabilities of variousmanufacturingprocesses.

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Dimensional Tolerance and Surface Finish

Figure 40.5 Relationship between relative manufacturingcost and dimensional tolerance.

Figure 40.6 Relative production time, as a function of surfacefinish produced by various manufacturing processes. Source:American Machinist. See also Fig. 25.33.

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Manufacturing a Sheet Metal Part

Figure 40.7 Two methods of making a dish-shaped sheet-metal part: (a)pressworking, using a male and female die, (b) explosive forming, using onedie only.

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Approximate Ranges of Machinery BasePrices

TABLE 40.5Type of machinery Price range

($000)Type of machinery Price range

($000)Broaching 10–300 Machining center 50–1000Drilling 10–100 Mechanical press 20–250Electrical discharge 30–150 Milling 10–250Electromagnetic and electrohydraulic 50–150 Ring rolling 500Fused deposition modeling 60–120Gear shaping 100–200Grinding Robots 20–200 Cylindrical 40–150 Roll forming 5–100 Surface 20–100 Rubber forming 50–500Headers 100–150 Stereolithography 80–200Injection molding 30–150 Stretch forming 400–> 1000Boring Transfer machines 100–> 1000 Jig 50–150 Welding Horizontal boring mill 100–400 Electron beam 200–1000Flexible manufacturing system > 1000 Spot 10–50Lathe 10–100 Ultrasonic 50–200 Single- and multi-spindle automatic 30–250 Vertical turret 100–400Note: Prices vary considerably, depending on size, capacity, options, and level of automation and computer controls.