In order to obtain an optimum condition of valve lift running with roller followers, in most cases the lobe profile needs to have a concave form (negative radii in the area of the cam lift profile). These negative radii can be less than 50mm. Conventional grinding equipment is not suitable to manufacture this type of cam profile. To avoid these disadvantages, a new type of composite camshaft has been developed.
Precision PM lobes are fitted by the thermal shrink fit process to a prepared shaft and as a result no grinding of the lobes is necessary. To avoid lobe grinding, a manufacturing process for the lobes and camshafts was developed, which produces a sufficiently accurate lobe form within the process.