Advances in Mechanical Clinching: Employment of a Rotating Tool

In the recent years, high efforts have been spent concerning the development of fast mechanical joining processes. This is due to the growing employment of materials that are difficult to weld and hybrid structures involving different materials. Mechanical clinching enables to solving the major concerns in this field. However, the formability of the materials represent a limitation to the successful employment of the process. The present research illustrates a new concept of clinching, namely friction clinching that differs from the conventional process by the employment of a rotating tool, which heats up the sheet (by friction) during the process leading to an increase in the material formability. Preliminary tests were performed to verify the feasibility of the process and determine a sound processing window. The process was applied to join thin aluminium sheets and Carbon Fibre Reinforced Plastic (CFRP) laminate. Morphological analysis and mechanical characterization of the joints was performed in order to evaluate the suitability of such the rotating tool to increase the material formability and thus the aluminium sheet integrity. According to the achieved results, the employment of the rotating tool enables to avoid crack formation in the metal sheet, improves the material flow and reduces the joining forces.