Virgin PTFE is capable in its own right, but when fillers, such as metal, are added, it enhances the material wear and deformation characteristics to more fully exploit their unique combination of chemical, physical and electrical properties.
Metal-filled PTFEs has the best wear properties, remarkable deformation strengths and good thermal conductivity, but poor electrical characteristics and chemical resistance.
PTFE-BR: Bronze is the most common metal filler, added in percentages of weight between 40 and 60%. Bronze-filled PTFE is used in bearings at high speeds (particularly where unhardened shafts used), Wear pads, piston rings.
PTFE-SSF: The other choice is stainless steel, added in percentages of weight between 5 and 10%. Stainless steel filled PTFE compounds are used for seats and seals requiring high heat and steam applications. This compound is also used in many applications involving food processing.