Analysis of a failed spur gear from a Vibro-Hammer

• Failure analysis of an induction-hardened spur gear.
• Analysis showed that the failure occurred due to tooth-bending fatigue.
• Premature fatigue was attributed to incorrect case-hardening practice.
• Fatigue was aggravated by poor machining, misalignment and incorrect heat-treatment.
• Recommended to correct the production and installation procedures.

This paper presents the findings from the failure analysis of an induction-hardened spur gear from a Vibro-Hammer, which failed after two months’ operation. The analysis of the gear showed that the failure occurred due to tooth-bending fatigue. The premature fatigue was attributed to incorrect case-hardening practice which was aggravated by poor machining, misalignment of the gear and incorrect heat-treatment prior to induction-hardening. It was recommended to improve the case-hardening, machining, installation and heat-treatment procedures in order to increase the service-life of the gear.