This new application of a heat treatment process is to improve the fracture toughness of a sliding cam lobe pack. The sliding lobe pack contains a barrel cam geometry with a shifting groove (1) that is used to slide the lobe from one position to the next by a pin from an actuator (2). The shifting groove contains a thin section of the wall described as the catch wall (3). The increased fracture toughness allows for higher shifting speeds. The microstructure of a conventional camshaft lobe is martensitic steel, but an austempered microstructure consists of bainite, which has a higher fracture toughness than martensite. By attaining a bainitic structure, a higher fracture toughness is obtained.
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