Polycarbonate hybrid friction stir welding joints: welding forces and quality indicators on 3D printed and solid sheets single and two-axis seams

Friction stir welding (FSW) was introduced to join parts that are difficult to join using existing methods. Joining polymeric parts using the FSW process is still a challenging task and has not yet been thoroughly investigated. Parameters such as the forces developed in the process are yet to be studied, but they affect the performance of the weld. The hypothesis of this research is related to the feasibility of joining 4 mm thick Polycarbonate (PC) plates using the FSW process, with different seam geometries, that is one- and two-axis paths, such as circular, linear, right, acute, and obtuse angles. This hypothesis was experimentally proven for bulk and hybrid joints by combining solid sheets and 3D printed PC parts. The effect of seam geometry on the forces developed in these FSW joining scenarios is reported herein, along with the temperatures developed during the process. Micro-CT was employed to study the dimensional deviation of the produced seams. Higher forces and temperatures have been reported, mainly in the acute angles of the produced seam. The joining of solid sheets produced better seams than hybrid joints. These findings provide valuable information for joining PC sheets using the FSW method.