Friction Stir Spot Welding
Friction stir spot welding is a special form of friction stir welding where spot-like lap joints are made without melting. It is used in automotive lightweight construction.
Physical-Chemical Mechanism of Action
In friction stir spot welding, the workpiece surface is processed by mechanical energy (stirring) and thermal energy (short, hot pulse). This leads to local deformation and diffusion of metal ions at the contact points, without melting the entire material band.
Metallurgical Relevance & Risks in Welding
The method enables high precision and low material loss. However, insufficient stirring or too short pulse time can lead to missing connections, while too long pulse times can result in overheating and possible material fusion.
Workshop Practice & Instructions
Use a friction stir welding machine with special spot welding programs. Make sure the stirring speed and pulse time are set correctly (typically 10-20 Hz for stirring speed and 50-100 ms for pulse time). The workpiece surface must be clean and smooth to ensure an optimal connection.