In situ stylus profilometer for a high frequency reciprocating tribometer

Abstract

Measuring the friction and wear characteristics of a tribological contact is essential to gaining a detailed understanding of its performance and predicted life. Wear rate and friction coefficient measurements are obtained from instrumented benchtop tribometers designed to replicate specific tribological contacts. Due to the difficulty of measuring wear in situ, measurements are typically made before and after an experiment. The wear rate must be assumed to be linear for it to be used to predict product life, however this is assumption can hide changes occurring during an experiment which indicate wear transitions. This paper details the design and validation of an in situ stylus profilometer for a reciprocating sliding tribometer to provide an insight into the wear transitions occurring during dry sliding of 52100 bearing steel against graphitic flake cast iron. The profilometer's performance was validated using ground roughness standards and the accuracy found to be approximately 110nm. Incubation, run-in and steady state wear regimes were identified by the profilometer and corroborated with friction coefficient data, providing an enhanced understanding of the tribological contact behaviour.

Friction and electrical contact resistance in reciprocating nano-scale wear testing of metallic materials

“…The probe displacement is also monitored continuously and recorded over the entire wear track enabling in-situ wear measurements. Several authors have reiterated the potential usefulness in measuring wear in situ rather than relying on post-test profilometry measurements [19,20]. In wear prediction it is often assumed that the wear rate is linear but this is generally not the case, particulary when there is a change in the predominant wear mechanism during the test [20,21].…”

“…Several authors have reiterated the potential usefulness in measuring wear in situ rather than relying on post-test profilometry measurements [19,20]. In wear prediction it is often assumed that the wear rate is linear but this is generally not the case, particulary when there is a change in the predominant wear mechanism during the test [20,21]. Table 1 compares the typical conditions in the new capability for nano-scale reciprocating wear to other approaches for multi-pass sliding contacts (repetitive scratch and nano-fretting) with the same instrumentation.…”