Defect characterisation using magnetic flux leakage inspection of tailor-welded blanks

With the increasing use of tailor-welded blanks (TWB) in the automotive industry, TWB manufacturers are struggling with the challenge to automate the quality monitoring process. The following paper examines the use of magnetic flux leakage (MFL) as a novel and economical means to evaluate the weld quality of TWBs. The development of a laboratory-based MFL inspection tool is outlined. The ability of the MFL technique to detect weld defects that occur in the production environment from CO₂ and Nd:Yag welds is clearly demonstrated. Defects include porosity, missed weld, pinholes, mismatch, concavity, and convexity. In addition, a discussion of defect signal characteristics is presented. The issues surrounding system implementation in a production environment are addressed and recommendations for future research are made.