Experimental study on triblogical behaviors of PA6 and PTFE polymers in the case of rolling friction

Abstract

Rolling/sliding contacts, such as rolling-element bearings or gears, are a keystone of many machines, which could not properly operate in absence of these components. Machine elements of this kind are typically made of certain variants of steel, whereby hardening processes are carried out in order to increase lifetime and reduce wear. Furthermore, proper lubrication of these tribo-systems is inevitable in order to guarantee a safe operation throughout the component’s lifetime. In recent years high performance polymers, such as Polyether ether ketone (PEEK) or polyamid 46 (PA46), have become an option for application in rolling/sliding contacts. Due to the low density and effective manufacturing processes, such as injection moulding, polymers enable lightweight design solutions under relatively low cost. A comparative investigation based on tribological properties including the friction and wear behaviour of two polymers (Polyamide 6, Polytetrafluoroethylene) was researched in this study. Where samples were prepared by machining for precast cylinders of these materials, and experiments were carried out using a device designed for this purpose, with two parameters (rolling speeds and loads) in select. The morphology of the polymeric transfer film which plays a lubricating role in the dry operation conditions was observed for both materials. The obtained results showed that the friction feature of PTFE was better than that of PA 6 which released high sounds during testing duo to adhesion bonds with metallic counterface. The main wear mechanism of polyamide was micro mechanical machining and deformation, while was adhesive wear for PTFE, and the wear rate of PTFE was very high compared to PA 6 which suffered from delamination wear in some cases