Surface Engineering Technologies for Improved Gear Efficiency

The traction (friction) of a tribological contact under low EHD film thickness relative to the surface roughness of the contacting pair is significantly influenced by the surface roughness. A reduction in roughness toward a superfinished surface reduces the traction coefficient. Gear efficiency for fuel economy can be improved with reduced gear surface roughness. The proposed cost effective effort uses run-in polishing (RIP) with special oil formulations as a means to reduce roughness in an assembled gear component or mechanical system. The notion of run-in polishing is illustrated with aeropropulsion gear materials and special aviation oil formulations. The formulations use reactive additives with good EP and poor anti-wear attributes. The addition of nano-additives enhances polishing wear. With an appropriate run-in protocol, surface polishing and traction coefficient equivalent to superfinishing is achieved. The proposed effort develops run-in polishing for Army gear materials and oils.