Friction Testing of Thermoplastic Composites

Friction phenomena play a major role in thermoplastic composite forming processes. In order to make use of the large potential these materials have, accurate CAE tools are needed that as a consequence incorporate temperature, pressure and velocity dependent friction behavior. To obtain a sound understanding of friction behavior a large number of friction measurement set-ups have been described in literature. A benchmark to compare different testing methods was proposed during the Esaform2010 conference. In this paper the material (Twintex PP) and testing conditions for the benchmark are briefly revisited and first testing results employing the in-house developed friction tester are presented. It is observed that the results reproduce very well at different conditions. Based on the Hersey number the Stribeck curve for the tested material combination is derived. It is concluded that a full state of hydrodynamic lubrication was reached with friction coefficients between 0.15 and 0.5. This opens up good perspectives for numerical modeling since all parameters are readily available in process simulations. Future comparisons within the context of the benchmark will assess the quantitative level of the identified coefficients of friction.