Magnet flux leakage inspection of tailor welded blanks

This work examines the application of Magnetic Flux Leakage (MFL) inspection to tailor-welded blanks (TWBs). TWB manufacturers are actively searching for systems of non-destructive evaluation (NDE) to meet the rising quality assurance requirements of their customers (predominantly automakers). This research presents the development of a laboratory based MFL inspection tool for TWBs. The industry requirement for single pass evaluation of TWBs has been specifically addressed in the design of a Hall Sensor Array (HSA). Test results have shown the single pass HSA to have equivalent performance to a raster scanned single sensor. Software to control translation, data acquisition and blank evaluation was designed and implemented. The software also has the capacity for synchronization with an industrial environment. Finally the applied flux density was investigated as an operating parameter of the system. It was found that the flux density could be optimized for a critical size of defect as determined by a manufacturer. It was found that by increasing the applied flux density MFL signals from larger defects are emphasized while those from smaller defects are neglected.