The valves are located in the cylinder head. These components control the entry of the fuel-air mixture of internal combustion engines into the combustion chamber (intake valves) and then the exit of the combustion products from the cylinder (exhaust valves) by the control. Proper fitting to the valve seats is essential for proper valve closure, thereby ensuring compression in the cylinder. The valves in the cylinder head move in the valve guides. Outside the valve guides is the valve spring followed by the spring plate and the valves are secured in place. With the development of engine technology, manufacturers use up to 5 valves per cylinder. Intake and exhaust valves require different materials due to different loads, and we also differentiate valves for petrol, diesel and gas engines according to the fuel used. They are made of a material with a welded shank or a sodium fill. Some examples of valve materials are: X45CrSi9-3; X40CRSiMo10-2; X53CrMnNiN21-9; X50CrMnNiNb21-9.