New tool design for friction stir weilding of polymer

Abstract

"The FSW uses plastic deformation, generated through friction and deformational heating to join the workpiece. Therefore, the technique is very popular and well adopted in Automobile industry for joining of Aluminium sheets. The low frictional heat generation, low thermal conductivity and different solidification behavior of the thermoplastics, hinders the use of FSW for joining. The conventional FSW process in the thermoplastics gives poor weld strength, due to low frictional heat and poor thermal conductivity. A new tool design is proposed and tested for the Friction stir welding of polypropylene. The newly developed tool provided with a resistance-heating element inside the tool, resolves the low frictional heat problem in case of FSW of thermoplastic. The improvement in weld strength of the welded samples found to be more than double compared to conventional FSW weld. Microstructural analysis of the joints were done to see the effect of microstructure on the weld strength. The tool heating, tool shoulder diameter, tool RPM and travel speed are important process parameters in FSW that affect the weld strength. The taguchi technique is used to optimize the process, by determining the relative effect of the the process parameters over the weld strength. The newly developed tool is promising for the industrial use, for joining of thermoplastics."