Construction and evaluation of a new tribometer for polymers

A versatile sliding friction and wear apparatus of the ring-on-flat type was constructed for polymers. This computer-aided tribometer has been designed so that the normal load and sliding speed of the specimen can be continuously varied and controlled over a wide range of load and speed. The accurate and fast-response data acquisition system allows for measurement of the friction force at the onset of displacement and sliding. As a result, static and dynamic coefficients of Friction (COF) can be identified in short term experiments. Long term experiments can provide wear rate of samples. To evaluate the performance of the machine, tribological properties of polyamide 6 and polyoxymethylene (polyacetal) were measured against a smooth steel plate. Contact temperature beneath the steel plate was measured and recorded. The effect of nominal pressure and sliding speed on COF were studied. Accuracy of the machine and reproducibility of the experimental data were evaluated by statistical analysis. It was shown that the machine can provide accurate results for tribological testing of polymers. The magnitude of COF, its dependency on test conditions, and wear rate of these two polymers agree well with the values and trends measured by other standard tests reported in the literature.