Enhancing the Durability of Springs for Car Seat Production

Abstract

The production of the A-model car seat began in 2020, and it must undergo an Endurance Test, which simulates repeated sitting and standing to evaluate its strength and lifespan. The seat must not sustain damage before the expected durability period at 500,000 cycles. However, in 2024, failures were detected in the zig-zag spring, a critical component of the seat. A thorough analysis identified multiple potential causes of the issue, and an in-depth investigation revealed that the primary cause was insufficient stress-relief annealing. This resulted in residual stress within the zig-zag spring, leading to premature failure during testing. To resolve this problem, the stress-relief annealing process was improved by increasing the heating duration from 15 minutes to 20 minutes at a temperature of 300 °C. This adjustment allowed the internal structure of the spring to release residual stress more effectively. Post-modification testing confirmed that the zig-zag spring successfully passed the endurance test without further damage.