Understanding the source of acoustic emission signals during the wear of stamping tools

Abstract

Stamping tools are prone to wear due to the increased use of advanced high strength steels in the automotive industry. For active monitoring of the wear state of stamping tools using acoustic emission, it is important to establish a correlation between specific wear mechanisms and the acoustic emission signals. An adhesive wear mode (galling), which is commonly observed on the stamping tool, can occur in combination with multiple abrasive wear modes on the workpiece, such as ploughing and cutting. This study will establish a correlation between the sources of the acoustic emission signal to the specific surface wear mechanism observed in the stamping process. Therefore, to investigate the source of acoustic emission signal, sheet metal stamping wear tests were conducted using un-worn and worn tool steel dies (AISI D2) and advanced high strength steel sheet (DP780). Accelerated tribology tests were also conducted using a scratch tester with the same material combination, where galling, cutting and ploughing wear mechanisms were observed. By correlating the acoustic emission features, such as power spectral density from the stamping test and the scratch test, it was observed that the change in the acoustic emission signal observed in the stamping process could be attributed to the galling wear mechanismsThis study contributes to the fundamental understanding of different wear mechanisms in sheet metal forming process, the resulting acoustic emissions, and how these can be utilized to develop active monitoring of the tools in the future.