Failure-Analysis Based Redesign of Furnace Conveyor System Components: A Case Study

Abstract

Any manufacturing equipment designed from scratch requires a detailed follow-up of the performance for the first units placed in service during the production ramp-up, so that lessons learned are immediately implemented in next deliveries and running equipment is accordingly updated. Component failure analysis is one of the most valuable sources of improvement among these lessons. In this context, a failure-assessment based design revision of the conveying system of a newly developed press hardening furnace is presented. The proposed method starts with a forensic metallurgical analysis of the failed components, followed by an investigation of the working conditions to ensure they match the forensic observations. The results of this approach evidenced an initially unforeseen thermo-mechanical damage produced by a combination of thermal distortions, material ageing, and mechanical fatigue. Once the cause−effect relationship for the failure is backed up by evidence, an improved design is proposed. As a conclusion, a new standard design for the furnace entrance set of rollers in hot stamping lines was established for roller hearth furnaces. The solution can be extended to similar applications, ensuring the same issues will not arise thanks to the lessons learned.

Keywords

• hot stamping
• press hardening
• austenitizing furnace
• high temperature fatigue
• thermal distortion
• conveying system
• refractory steels
• furnace component failure