A study of fiber-capstan friction. 2. Stick–slip phenomena

A study was made of the friction of nylon fiber (monofilament fishing line) rubbing against spinning aluminum and nylon capstans (cylinders), in the presence of various lubricants. Use of variable speed drives with appropriate gear reducers allowed variation of sliding speed over four orders of magnitude and monitoring of the entire Stribeck curves, from boundary through mixed to hydrodynamic sliding, for these systems. The effects on friction of seven system variables—cylinder material, sliding speed, system elasticity, input tension, lubricant viscosity, lubricant additives and cylinder surface roughness—were investigated. Special attention was given to the effects of elasticity on friction and the character of sliding. Factors which determine the critical speed where stick–slip sliding just appears or disappears are defined.