Friction Stir Welding (FSW): The effect of tilting angle

Friction Stir Welding (FSW) is solid-state process of combining two materials using frictional heat generated by rotating tool travel along the weld line. Development of FSW suffers implementation challenges due to expensive actual FSW machine available commercially. As alternative, a typical 3-axis conventional CNC milling machine offers comparable capability to be utilized for this technology as well. However, few modifications on machine parts need to be executed first before it is fully compatible to serve FSW purposes. The first objective of this study is to design and fabricate an adjustable-angle fixture to assist CNC milling machine on accommodating the variety tilting angle during FSW process. Upon completing the concept selection, designing, and fabrication phase, the final fixture prototype will be used to experimentally execute the second objective of this project, which is to determine the effect of varying the tilting angle during the FSW process. The resulted weld joint will be qualitatively analyzed in term of any presence of weld defects. The visual inspection on the weld joint shows that increasing the tilting angle at optimum range of 3.50 to 5o can reduce the possibility of having tunnel defects. This can be justified by the inclined orientation of welding tool’s axis of rotation which can randomize the flow of plasticized material during mixing and stirring process. However, further increment of tilting angle more than 5o is not favourable as it will only encourage severe flash formation and reduce weld maximum joint efficiency.