Thermo-Mechanical Characterization of Friction Stir Spot Welded HDPE Sheets

Friction Stir Spot Welding (FSSW) is a rapidly evolving technology that is increasingly becoming one of the widely adopted technologies in the industries for joining alloys of various metals like titanium, aluminum, magnesium and even polymeric materials that are hard to weld by conventional fusion welding processes. This work presents an analysis of the thermo-mechanical conditions in Friction Stir Spot Welding (FSSW) of commercial High density Polyethylene sheets. An experimental campaign was carried out on a Vertical Milling Machine, modified to work as a Friction Stir Spot Welding machine and lap joints were obtained on couples of HDPE sheets. The study was carried out using a set of tests to investigate how the friction stir spot welding process parameters namely tool rotational speed, axial feed rate, dwell time and the plunging depth effect the temperature distribution and mechanical properties of the joints. Experiments were designed using Response Surface Methodology Design of Experiments. Furthermore, a mathematical model for peak temperatures and lap shear strength was developed.