Official Answer
Answer
Acoustic noise in wave spring assemblies is usually caused by 'stick-slip' friction between the spring and the housing (bore) or between the turns of a nested spring. As the spring deflects, its diameter changes, and if the interface is dry or the surface finish is too rough (e.g., $> 32$ RMS), the spring 'stutters' rather than sliding smoothly. This is common in steering column assemblies. Troubleshooting involves checking for wear marks on the bore wall. The solution is often the application of a dry-film lubricant (like PTFE or $\text{MoS}_2$) to the spring or improving the housing surface finish. In some cases, switching to a different material like Beryllium Copper can reduce noise due to its different friction coefficient.
