The possibilities of and limits to detecting incomplete fusion via in-process monitoring in the case of laser welding

Laser welding has a whole series of benefits such as high welding velocity or minor heat yield which is why it is becoming increasingly important. Meeting strength and quality requirements for welding seams is of eminent significance in automobile design. Unfortunately, there might be problems due to the degassing gaps needed between the joining parts when using the galvanized sheet metal that is customary in car body design. This causes incomplete fusion to form with excessively large gap dimensions that cannot be identified from outside. Nor do process monitoring systems available on the market detect these faults with sufficient reliability. VW Sachsen GmbH and the Fraunhofer Institute for Machine Tools and Forming Technology studied the reasons for the inadequacies of conventional systems in the MAINE X joint research project. This article presents the findings and makes recommendations for sufficient methods of detection.