Fabrication of a crankshaft.

Replies

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  mechky

  zaveri

  It is said that the crankshaft has to be produced only by the forging method, due to the large number of forces that act on it. but however The "AUTOMOTIVE MECHANICS" text book by Crouse and Anglin says that it can be produced by casting method as well. Are they justified ?

  Crankshaft can be produced by forging, casting as well as by machining. The selection of manufacturing process is done on the basis of mechanical properties required in a crankshaft.
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  zaveri

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  But mostly it requires high strength, so isn't forging the only operation available for use. if we were to go for casting process, then hot tears would occur at the junction between the crank pins and the webs and that is where it would fail due to twisting moment
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  mechky

  zaveri

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  But mostly it requires high strength, so isn't forging the only operation available for use. if we were to go for casting process, then hot tears would occur at the junction between the crank pins and the webs and that is where it would fail due to twisting moment

  Yes, forged crankshafts have better mechanical properties than cast crankshafts. But, cast crankshafts are are also successfully employed and have sufficient properties. Also casting is a relatively cheap process and with proper precautions defects can be prevented. Cast crankshafts are suitable for moderate performance applications and in some particular applications where cost of forging is not justified.
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  prshntsingh

  when an engine runs, the crankshafts are under high stress...to bear that stress crankshafts are forged because during forging process the grains of the metal/alloy are realigned which removes the internal stresses in the metal...and during casting the grains not aligned hence internal stresses are present which causes fracture in the casted crankshaft.
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  Ramani Aswath

  Powder metallurgy route can also be used for making crank shafts.
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