A review on friction stir welding of thermoplastic materials: recent advances and progress

Friction stir welding (FSW) was developed initially for welding aluminium alloys which were difficult to weld using conventional welding techniques, and a remarkable success was accomplished in these alloys and other wide range of metals. Then, this technique has been applied without any modifications for welding polymeric materials. As a result, conventional FSW of polymeric materials did not achieve satisfactory joint strength due to the huge differences between the properties of metals and thermoplastic materials. As a consequence, several modifications, developments and patents have been introduced to harmonise this technique with thermoplastic materials. This work aims to present the problems associated with the application of conventional FSW of polymers and the methods that have been developed to overcome these issues and make comparisons between them.