Heat-assisted Friction Stir Welding of HDPE

Abstract

Friction Stir Welding is a non-conventional welding/joining process in which a rotating pin of specialized geometry produces frictional heat due to the rotational and translational motion of the pin relative to the work material and cause the work material to deform into glass transition phase. Friction stir welding is mainly applied to soft metals but recently attempts have also been made in the field of thermoplastics. Work on different polymers is in progress hence an attempt is made to test the HDPE. When dealing with thermoplastic is confronted then frictional heating is not capable to deliver the desired results due to the nature of bonding, hardness and thermal conductivity henceforth some innovation is required. A developed specialized tool for this purpose to deliver the required objective. This tool along with different profiled-pin is accompanied by heat assistance equipment which is used to produce a controlled and uniform temperature along the tool rotational and translational motion. Experimental setup is maintained on the CNC milling machine to carry out the demonstration. Visual inspection is carried out to vet the different profiled tools results. Best among the different pin geometry results are then investigated by Taguchi Technique to find the quality of the weld seam. Taguchi Technique is indeed selected due to the minimum of arrangements to find the results. Parameters selected for Taguchi Technique are tool rotational speed, translational motion and temperature on the weld bead to find the individual effect of each parameters and try to evaluate the parameters combination effect in terms of UTS and %EB. It is identified from both the SN ratio and Mean value plot that temperature has the most of significance which is followed by welding speed and then the least important is rotational speed. An optimum combination is found in the attempted experiments which gave us strength of 90.29% and the combined joint efficiency of UTS with percent elongation %EB is calculated to be 66.51%. Parameters produced this result are temperature and welding speed are at highest level while rotational speed at the lowest level amongst the decided parameters level. Results obtained from ANOVA table showed that the significant factors are temperature and welding speed while the rotational speed contribution has the least contribution.