Valve seats are circular ring of heat resistant bronze or steel on which a valve of an internal combustion engine rest when closed. It is one of the most critical components of an engine. The valves are a critical component because they are the foundation of the valveterian. This seat provides a surface for the valve to seal against when they close so that there is no loss of compression or pressure from chamber. The valve seats help in the cooling of the valves by conducting the heat away from the valves into the cylinder.

Major functions of the valve include:
a) They are hard to wear down under high heat and high load
b) They hold strength when the valve is mounted
c) The valve seats prevents compress gaseous body and other combustion gases from leaking
d) They release the heat in the valve to the cylinder head and helps in cooling

The valve seats deserve a lot of attention whether you are rebuilding a stock engine or building a performance engine.The diameter of the seats and the contour of the angles that are machined into the face of the seats also limit how much air the engine can flow at any given valve lift and rpm. The seat also determines the valve height and affects the valveterian geometry and valve lash.

To meet the different strains, an optimum material composition of the valve seat inserts must be found.In the most recent engine generations of renowned car manufacturers, valve seat inserts made of sintered material (powder metallurgical procedure) are used. Not only must the operating conditions in the engine be considered, but also the machinability of the material for the engine reconditioning.