The roles of contact conformity, temperature and displacement amplitude on the lubricated fretting wear of a steel-on-steel contact.

A R Warmuth,P H Shipway,W Sun

doi:10.1098/rsos.150637

Abstract

This paper investigates the effect of contact geometry, temperature and displacement amplitude on the fretting behaviour of an aero-turbo oil lubricated cylinder-on-flat contact. To be effective, the lubricant needed both to penetrate the contact and then offer protection. Lubricant penetration into the fretting contact is found to be controlled by two physical parameters, namely (i) the width of the contact that remains covered throughout the fretting test and (ii) the lubricant viscosity. The protection offered by the lubricant (assuming that it has successfully penetrated the contact) is influenced by four physical parameters, namely (i) lubricant viscosity, (ii) traverse velocity, (iii) nominal contact pressure, and (iv) chemical effects. The relationship between the three experimental parameters which were varied in the programme of work (temperature, fretting displacement and cylinder radius) and physical parameters which influence the protection offered by the lubricant film can be competing, and therefore complex wear behaviour is observed. The roles of the various parameters in controlling the wear behaviour are presented in a coherent physical framework.

Highlights

Fretting is defined as small amplitude oscillatory motion between bodies that are in contact
This study has demonstrated that lubricant viscosity strongly influences fretting damage, in this work, variations in viscosity were produced through changes in temperature
It is notable that the shift in behaviour from that at lower temperature to the behaviour observed at the higher temperatures itself moves to higher temperature as the displacement amplitude increases

Summary

Introduction

Fretting is defined as small amplitude oscillatory motion between bodies that are in contact. In addition to its role as a lubricating fluid, the lubricant will restrict oxygen access into the fretting contact that will in turn affect the development of the oxide debris bed that is commonly associated with fretting wear. Owing to the very small and reciprocal motion associated with fretting, lubricant penetration into the contact may be poor [3]; it has been argued that this poor penetration is the cause of lubricated fretting contacts having been found to exhibit higher values of the coefficient of friction (COF) than observed in non-lubricated contacts [4].

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Conclusion