Extension spring longevity

[Luigi805]

I have a small extension spring, .028" wire that has a single loop turned out to 90 degrees on ea h end.

I've constructed a cycle tester for this spring , but I'm breaking them in under 10,000 cycles. I'm only applying .120" of pull on the spring during testing.

This spring is made from music wire.

Does anybody have any suggestion as to what I can do to make them last longer? New material perhaps or a post process ?

Thanks

 

[israelkk]

Did you try to calculate the stresses in the spring when you extend it 0.120"?

In .028" wire diameter you probably will not find a better material than music wire. There is a modified music wire called Rocket Wire that supposed to be 10% stronger but I would check the design.

Can you post the spring complete data?

Where does it break? in the spring coils of the ends?

 

[desertfox]

Check the stresses in the end loops.

desertfox