Effects of Oil Viscosity on Seizure

Abstract

Oil viscosity is an important factor in oil film formation ; its effects on the scoring resistance of gears have been examined. In spite of scoring taking place easily where specific sliding is high, few papers have treated the specific sliding as important. As a basic study to establish gear design procedures for better resistance to scoring, we examined the effects of oil viscosity on antiseizure capacities of mineral base oils. The experiments were carried out using a two-cylinder test rig under various specific sliding conditions. In the higher specific sliding range the antiseizure capacities rise with an increase in oil viscosity. In the lower range, however, the effects are nominal ; thin oils are applicable in severe conditions of heavy load, high sliding velocity, and high bulk temperature where thick EP oils are ordinarily used. A method for applying these results to the scoring design of case-hardened spur gears was proposed.