Preset Spring

[mjhward]

I have a compression spring (.42OD, .047wd) in a static situation with no enviromental conditions. I am using Music Wire. In it's static condition, I estimate that I am at 56% of tensile strength. Spring mfgs. are telling me that if I am above 45%, I will get permanent set. I know if I preset the spring, I can use up to 60% of tensile strength.

This spring goes into an assembly and some spring mfg. told me that they could not remove set in this quantity. Is the preset operation as simple as taking the spring to solid height or is there more to it? Could this be done at an assembly station with a simple jig?

 

[NickE]

yep pre-setting is taking the spring to solid height. some times this is done at elevated temperature. You could use a simple jig at the assembly station to do this (obviously you will need to guard against slippage and breakage)

 

[israelkk]

However, the spring may be shorten after preset therefore, the force at the assembeled position may be lower than your design load. Usually the spring naufacturer makes the spring longer than your design and after preset the spring gets the designed dimensions.