Valves are nitrided to increase the exhaustion
strength, Chrome plated to increase the wear resistance
and Stellited (Seat hard Faced) to get high hot
hardness at the seat.
The guides are usually made of cast iron by casting
process. Sometimes, shoulder bushes are provided
to position the guide in cylinder head. The Valve-Guides
are also available in Brass material for certain
applications.
These are produced by centrifugal cast process
to obtain closed grain dense structure to meet
their functional properties.
Valve Tappets are made in “Chilled Cast
IRON in shell moulds.
