Relieving Stress in Mechanical Springs

A critical step when producing our final product is ensuring the strength of our material.  When springs are coiled they are stressed from all the bending and physical manipulation that has occurred during formation.  Spring manufacturers use a duration of heat, dependent on size and type of the material, to increase the material strength back to levels prior to coiling.  It is even possible for the heat to increase strength levels greater than when the raw material was supplied.  Keep in mind higher temperatures and longer time is not necessarily more beneficial, there are sweet spots for all the desired materials that SPS uses.  After a certain period of time you are doing more harm than good with your excessive heat.

 

Materials react to the heat in different ways; for example, Music Wire will reduce its diameter in heat.  Most Stainless Steel materials will increase their diameter in heat. The exception to stainless steels are 17-7—which typically, depending on its composition, does not move at all when exposed to high temperatures.  Keep in mind that the more coils a spring has the more revolutions it will make.  If you have a spring with five coils it may rotate 10 degrees, compared to a spring with 100 coils which may change an entire revolution.  Depending on if the spring is LH wound or RH wound the spring could rotate clockwise or counterclockwise, this makes it very important to understand your direction, material type, and effects of heat before you finish your “Green” parts.  We will always run our green parts through heat to make sure our finished product is at the desired position.