Tribometer testing of drawn rope wire in representative fretting contacts: The importance of lubrication mechanisms and lubricant base fluid viscosity in minimising fretting wear

The fretting wear scars that form at internal contacts within wire ropes can have a significant influence on fatigue cracking of the rope wires. The nature and progression of this fretting wear is significantly influenced by lubricant and lubrication-related factors. Using a laboratory-scale fretting wear test, the influence of various lubrication-related parameters on the fretting wear of drawn wire was investigated, particularly the importance of base oil viscosity. Because there are many interrelated lubricant properties and influences, multivariate statistical analysis was used to identify the most significant lubrication-related factors on fretting wear. The viscosity of the grease base fluid and the formation of a stable interface layer in the Gross Slip fretting regime during the run-in phase were found to be the most influential factors in long term fretting wear. Galvanised drawn wires were more sensitive to base fluid viscosity than bright drawn wire because extruded zinc and wear debris features restricted lubricant access to the contact, meaning that lower base fluid viscosity, lower bulk viscosity and higher oil bleed improved lubricant supply.