In the process development of a new spring for shock absorption in motorcycles, fatigue resistance cannot always reach the design standard. Spring fractures were sent to the author for failure analysis to identify reason behind and proposals for improvements were expected. Based on information from the spring manufacturer and spring fracture analysis, the reason for earlier breakage than design standard was determined to be process flaws. More specifically insufficient shot peening and embrittlement induced from electroplating were observed. This has been demonstrated by experimental results from an uncoated spring. A process optimization was proposed, and now, spring fatigue life has reached the design standard with the optimized process.
