Failure analysis of cutting die used for the production of car racks

The failure of a cutting tool intended for the production of car racks was investigated. The tool consisted of two parts, the mould and the counter-die. The die, made of AISI O1 steel and designed for cutting metal sheets up to 2 mm thick, failed during the final grinding process, before performing any production service. Recorded history was collected, with data concerning the material selection, the manufacturing conditions and the final heat treatment. The die was inspected visually and than photographed. Hardness measurements and chemical analysis were performed in order to identification the tool material. A representative sample was subjected to magnetic-particle inspection for the emergence of surface cracks. Specimens were examinated by optical and electron microscopy (SEM). The type of failure and the principal factors that caused it are studied, and some suggestions are presented, in order to avoid similar failures.