Transition Temperatures with Four Ball Machine

Abstract

The seizure phenomenon in the Four Ball Wear Machine is studied using dilute solutions of stearic and capric acids in cetane and a paraffinic mineral oil. Load, sliding speed and bulk lubricant temperature are investigated. The “flash temperature” at the area of rubbing contact is estimated using Blok's theoretical treatment. It is shown that the estimated surface temperature corresponding to the transition from no-seizure to seizure increases with decreasing ratio of load to speed. This relationship of transition temperature to load-speed ratio for the Four Ball Machine represents an extension of previously reported transition temperature vs. load-speed ratio data obtained with a Pin-on-disk Machine. Thus, it appears possible quantitatively to relate the condition for the onset of catastrophic wear or scoring in these two different types of bench boundary-lubrication machines provided operational variables are properly considered. It is also shown that the transition-limited load obtained in these two bench boundary-lubrication machines qualitatively follows the same laws as wear- and score-limited loads of gear sets.