Stirring pin
A stir pin is a profiled tool for friction stir welding that plunges into the joint zone and plasticly heats and transports material.
Physical-Chemical Mechanism of Action
The friction stir tool heats the metal locally through mechanical friction and plastic deformation. This leads to uniform heating of the material without porosity or melting effects.
Metallurgical Relevance & Welding Risks
A defective tool can cause uneven heat generation and thus stress concentration, which can result in cracks or distortion in the material. Too high a tool speed increases the risk of hot cracking, while too low a speed increases the risk of porosity.
Workshop Practice & Instructions
Use a tool with the correct profile and speed. The speed should be between 100 and 200 mm/s, depending on the material and the joint area. Make sure the tool is clean and the joint area is free of dirt or corrosion.