Design is critical
Welding tool design is critical in FSW. Optimizing tool geometry to produce more heat or achieve more efficient stirring offers two main benefits: improved breaking and mixing of the oxide layer (more efficient heat generation) yielding higher welding speed - and enhanced quality. Tool materials should feature high hardness at elevated temperature and should retain this hardness for an extended period. The combination of tool material and base material is therefore always crucial to the tool's operational lifetime.