Tribology of polymer injection-molded stainless steel hybrid gear

In order to verify our hypothesis proposed from the previous paper where a polymer sheet-adhered metal hybrid gear has superior properties of antiwear, self-lubrication and noise reduction, studies were first made on a possibility of nylon66/poly(phenylene oxide) (PPO) alloy injection-molding onto shot-blasted aluminum and steel disks. Adhesion of the coated polymer layer to the metal surfaces and no crack formation of the polymer layer were found under certain molding conditions. This molding method was then applied to a stainless steel spline, a sort of gears used in clutches, giving rise to adhesion of the coated polymer alloy without surface crack formation of the resultant hybrid gear. Tribological properties of the hybrid gear were examined by a vibrational test under a severe condition of a predetermined acceleration amplitude of 10 G and a frequency of 100 Hz. A very high antiwear was found in the hybrid gear, while a same type of stainless steel gear without polymer coating showed a severe wear not only on the gear teeth but also on the meshing teeth of the counter stainless steel disk. Taking into consideration excellent tribological properties with antiwear, self-lubrication and noise reduction, it is concluded that the injection-molded hybrid gear is promising for a wide range of industrial applications.