Acoustic emission-A promising and challenging technique for process monitoring in sheet metal forming

Acoustic emission (AE) is a non-destructive testing method with a high potential for quality and process monitoring in sheet metal forming. In this paper the possibilities and limitations of this testing method with regard to sheet metal forming are presented. For this purpose several rectangle cups were manufactured from the low carbon (DC06) as well as the dual-phase steel (HCT600X) by deep drawing. The analysis of the measured acoustic emissions was focused on two objectives. First, a correlation between the cracking and the acquired resulting acoustic emissions were created. The second objective of the analysis was to verify the suitability of the AE-technique for process monitoring. The results have shown that acoustic emissions arised during the deep drawing process enable not only the detection of crackings, but also different process deviations such as lacking lubrication and wrong material. But it has to be considered that the feasibility of the acoustic emission technique as a process monitoring tool depends from the material ductility which limits the fields of application.