Due to the cyclic impact loading on the contacting surfaces
of the cam and the follower, it often gives rise to premature
wear of cam profile and affects a routine run of the valve
gear such as the rotational speed, valve displacement and the
torque. On the other hand, simultaneously the most serious,
under cyclic bending and torsion, fatigue fracture of camshaft
initiating at stress concentration easily occurs. Therefore it
demands the camshaft has not only excellent wear resistance
but also adequate anti-impact toughness