The cam bearing is subjected to periodic shock loads. The contact stress between the cam and the tappet is very high, and the relative sliding speed is also very high, so the wear of the cam working surface is more serious. In view of this situation, the camshaft journal and cam working surface should have high dimensional accuracy, small surface roughness and sufficient rigidity, as well as high wear resistance and good lubrication.
Camshafts are usually forged from high-quality carbon steel or alloy steel, and can also be cast with alloy cast iron or ductile iron. The journal and cam working surface are polished after heat treatment.