Machinability of Bronze-Filled PTFE

Bronze-filled polytetrafluoroethylene (PTFE) (at 60% bronze by weight) is a blend of lubricious materials that is typically used as a bearing and gliding material under heavy load. Where pure materials, such as copper or PTFE, are typically used as impactor and/or target materials, the combination of the bronze and PTFE provides the ability to vary the impedance from the individual materials, to access difference pressure regimes. We will be studying this material as both an impactor and/or target materials in gas gun driven, one-dimensional, planar shock physics experiments. Part of the requirements to use a new material in shock physics experiments is the machinability of the material. For this bronze-filled PTFE, the machinability is relatively high with good dimensional stability, provided sharp tools with high rake are used. Heat induced through machining does seem to influence dimensions growing and shrinking in small or thin-walled parts, however they return to dimension once restored to ambient conditions. The machined surfaces yield a high luster when lapped or polished. However, the material deforms easily when struck or dropped on hard surfaces but seems to resist cracking when bent. Compared to normal PTFE, the bronze-filled PTFE has a higher density, holds dimensions better when cutting and has more rigidity and toughness.