US Patent 7168858 Surface densification of powder metal bearing caps

A high performance main bearing cap has particular surfaces densified for improved fatigue crack resistance. The surfaces densified are the bolted face (F) inside of a perimetral margin and outside of bold head interface areas around the main bolt holes (B), the surfaces of the main bolt holes and the side bolt hole threads (S). Preferred methods of densification are single needle programmable pattern peening of the bolted face peened area, over-burnishing of the bolt holes, and forming the threads rather than cutting them for the side bolt threads.