18~chapter 18

18~chapter 18 - Materials: engineering, science, processing...

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Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon
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Process Selection Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon Figure 18.1 Table 18.1 The selection strategy for processes is similar to that for materials Design requirements should be put in terms of constraints and objectives to be used to screen, rank, and finally select an appropriate process
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Material – Process Compatibility Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon Figure 18.2 Each of the three process families – shaping, joining, and surface treatment – has its own set of characteristic attributes One process attribute applies to all three families – compatibility with materials
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Shaping Processes Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon Figure 18.3 There are limits to the size of a component that a process can make
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Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon Figure 18.4 Along with mass, there is a limiting value for section thickness that a given shaping process can handle
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Physical Limits to Size and Section Thickness Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon Figure 18.5 Casting and molding rely on material flow in the liquid or semi-liquid state Lower limits on section thickness are imposed by the physics of flow – flow of liquid metal or polymer into thin sections is opposed by surface tension and viscous forces – loss of heat into the mold increases viscosity and may result in premature solidification
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Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon Figure 18.6 Upper limits to size are set by problems of shrinkage – the outer layer of a casting or molding solidifies first, giving it a rigid skin – when the interior solidifies, the change in volume can distort the product or crack the skin Keeping section thickness and cross-section uniform reduce the chances of differential shrinkage
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Materials: engineering, science, processing and design, 2nd edition Copyright (c)2010 Michael Ashby, Hugh Shercliff, David Cebon Figure 18.7 Metal shaping processes such as rolling, forging, or
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This note was uploaded on 02/15/2012 for the course MASC 310 taught by Professor Nutt during the Fall '08 term at USC.

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18~chapter 18 - Materials: engineering, science, processing...

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