Effect of coating material on wear in internal gears

Abstract

Theoretical and experimental investigation of wear during coupling in internal gears coated with various polymeric coating materials was performed in this study. In the theoretical part of the study, Archards' wear formulation was adapted to internal gears and wear behavior in various conditions was determined. Moreover, a fatigue and wear testing apparatus having similar working principle with FZG (Forschungsstelle für Zahnrader und Getreibbau) closed circuit power circulation system was designed and manufactured to experimentally investigate the wear in internal gears. Internal gear-pinion couples manufactured from St50 material were coated with various polymeric materials, namely PTFE (polytetrafluoroethylene), MoS2 bonded with polyamide, MoS2 bonded with epoxy in the experimental study. An uncoated internal gear was also investigated to find out the performance of coated gears. Variation of wear depth on tooth profiles of internal gears were determined theoretically and experimentally. Theoretical and experimental studies showed that polymeric coated internal gears have more wear resistance than uncoated ones by means of high lubrication ability and low friction coefficient of coating materials. It was also observed that high corrosion resistance of polymeric coatings protected metallic surfaces and decreased corrosive wear.