Cracking Analysis of Polytetrafluoroethylene(PTFE) Bushes

Part of Polytetrafluoroethylene(PTFE) bushes were founded to have axial cracks on the surface after they were made of PTFE bars. Macro and micro observation on the fracture surface was carried out to analyze the failure mode and cause, and the fracture surfaces were compared with man-made ones. The results show that original cracks defects in raw PTFE bars formed during production is the main reason for the cracks in PTFE bushes. The additive incompletely infiltrated PTFE resin at lower temperature, resulting insufficient fibering of PTFE resin in the process of extrusion. As a result, cracks occurred in the cooling process. This problem can be effectively avoided by strictly controlling the temperature and time of resin infiltration with additive in PTFE bar production process.