Alternative to Shotpeening

[koza19]

I have a customer which we manufacture springs that get shotpeened and the customer is having issues with the shot media getting wedged in between the last active coil and closed coil. The spring is used in a hydraulic pump and they do not what any foreign material that could cavitate the pump. Does anyone know of a different shotpeening method that doesn’t use shot media?

 

[desertfox]

Hi ckozka

If fatigue is a concern with your spring then the spring should have the last coil closed and ground square, if you leave the end plain and not closed then the load applied will be eccentric to some degree and result in a higher stress for a given load on that spring.
Israelkk's idea sounds very good to me using preset.

desertfox

 

[koza19]

Hi guys I think you guys might be on to something. So you think just presetting the part will cold work the material enough to reach the 10mm life cycle? I have attached a spec sheet of the part.
Let me know your thoughts

 

[israelkk]

Is the spring deflects between the load points only? If this is the case the calculations indicate that it should withstand the 10M life cycle. However, is there a possibility of impact or very high load rates? If not I would check again surface conditions of the spring under X10 magnifications for surface defects.

Is the spring accepts electro chemical coating such as zinc? If it does check for hydrogen embrittlement correct removal process.

With regard to preset you need to calculate for maximum available cold working to get the most of the preset process.