Friction characteristics of polymers applicable to small-scale devices

A review of the critical features of a published micro-tribometer design, which was intended to improve on the dynamic response of typical commercial instruments, leads to its use with a modified technique. Data post-processing is introduced to partially compensate for some potential systematic errors. This approach is demonstrated by a preliminary study of the coefficient of friction (CoF) in sub-mm length reciprocating sliding motion for samples of polytetrafluoroethylene (PTFE) and an R11 acrylic formulation made by micro-stereo-lithography, with an SiO2-coated silicon wafer used as a control sample. Testing covered normal loads in the region of 10 mN–60 mN, at scan frequencies up to 9 Hz, corresponding to sliding speeds in the broad region of 1 mm s−1. While the control samples closely adhered to Amonton's laws over all the test parameter ranges, the CoFs of the two polymers showed contrasting patterns of dependence on sliding speed and repetition rate. Such results have implications for how polymers might be used effectively in future designs for small mechanical systems. They indicate a clear need for further development of the testing methods and large-scale studies of tribological behaviour and its underlying mechanisms under the specified micro-scale conditions. •We evaluated the need for applying micro-tribometry techniques intended to measure at faster speeds than commercial ones.•Friction behaviours in short-range reciprocating motion could be significant for the wider use of polymers in future MEMS.•There is benefit in undertaking further studies in this regime and extending it to a wider range of forces and speeds.•Further research in the instrumentation and polymer formulations is essential to this larger programme of future work.•I hope this paper is suitable for “Tribology International”.