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Unformatted text preview: f sufficient rigid construction to withstand thermal and mechanical distortion.
8. It should have sufficient support for the piston pin. 32.7 Material for Pistons
The most commonly used materials for pistons of I.C. engines are cast iron, cast aluminium,
forged aluminium, cast steel and forged steel. The cast iron pistons are used for moderately rated Spark plug Carburettor Twin-cylinder
aeroplane engine Cylinder head Propeller 2. Side view 1. Front view
Twin cylinder airplane engine of 1930s. 1134 n A Textbook of Machine Design engines with piston speeds below 6 m / s and aluminium alloy pistons are used for highly rated engines running at higher piston sppeds. It may be noted that
1. Since the *coefficient of thermal expansion for aluminium is about 2.5 times that of cast iron,
therefore, a greater clearance must be provided between the piston and the cylinder wall (than with
cast iron piston) in order to prevent siezing of the piston when engine runs continuously under heavy
loads. But if excessive clearance is allowed, then the piston will develop...
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