Oil Tempered Chrome Silicon Compression Spring

(click on thumbnail to enlarge)

This Compression spring, made with 0.120” Oil Tempered Chrome Silicon wire, requires multiple production steps. The spring is coiled using a unique twist cut, that allows us to cut the spring with absolutely no cut-off burr whatsoever. After stress relief, the spring ends are ground to a minimum 270 degree bearing surface. Even though the blueprint tolerance allows for a free length variation of +/-0.025”, we coil to a much tighter tolerance, (+/- 0.005”) in order to maintain a more consistent result in end grinding.

Because the spring is highly stressed, set removal is necessary. After grinding each spring is compressed to solid height one time to remove permanent set. Removing set means that the spring is deflected past the elastic limit, and will not return to the original free length. The spring will be shorter. To account for this, the spring is deliberately coiled too long to account for this loss in free length. After set remove, the spring will be at the target free length. Set removal introduces beneficial residual stresses into the spring which will allow it to work a little harder and last a little longer than a typical design would suggest.

After set removal the springs are tumbled to remove and residual grinding grit and to soften any sharp edges left over from grinding.