Large-scale tests on friction and wear of engineering polymers for material selection in highly loaded sliding systems

Tribological properties of polymer materials are traditionally tested on small-scale test rigs because of cost-efficiency and flexibility. For highly loaded applications (e.g., sea lock doors, retaining walls, positioning systems) however, large-scale tests should be performed for estimating the frictional behaviour and wear lifetime of different engineering polymers more accurately under nearly working conditions. In present paper, two filled polymer grades covering a broad range of mechanical properties polyethylene terephtalate (PET)/teflon (PTFE) and ultra high molecular weight polyethylene (UHMWPE)/carbon are slid against high alloy steel, stainless steel and epoxy resin, in order to make a selection for its use as bearing material under dry and lubricated conditions. A general thermal model is evaluated for present test rig. The coefficients of friction on large-scale tests are lower than those obtained from small-scale testing. Polymer wear rates are calculated from weight loss and compared to dimensional measurements (thickness reduction) including elastic deformation, thermal expansion and creep.