Term
| What are the differences between bulk deformation processes and sheet metal processes? |
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Definition
| In bulk deformation, the shape changes are significant, and the work parts have a low area to volume ratio. In sheet metal processes, the area-to-volume ratio is high. |
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Term
| Extrusion is a fundamental shaping process. Describe it. |
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Definition
| Extrusion is a compression process in which the work material is forced to flow through a die orifice, thereby forcing its cross section to assume the profile of the orifice |
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Term
| How does increasing temperature affect the parameters in the flow curve equation? |
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Definition
| Increasing temperature decreases both K and n in the flow curve equation |
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Term
| Indicate some of the advantages of cold working relative to warm and hot working. |
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Definition
| Advantages of cold working are (1) better accuracy; (2) better surface finish; (3) increased strength due to work hardening; (4) possible directional properties due to grain flow; and (5) no heating of work required |
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Term
| What is isothermal forming? |
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Definition
| An isothermal forming operation is performed in such a way as to eliminate surface cooling and thermal gradients in the work part. This is accomplished by preheating the forming tools |
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Term
| Describe the effect of strain rate in metal forming |
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Definition
| Increasing strain rate tends to increase the resistance to deformation. The tendency is especially prominent in hot forming operations. |
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Term
| Why is friction generally undesirable in metal forming operations? |
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Definition
| Reasons why friction is undersirable in metal forming include the following: (1) it inhibits metal flow during deformation, causing residual stresses and product defects; (2) it increases forces and power required; and (3) it increases wearing of the tools |
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