Hi,

I have an idea how to measure capability in a machine for shot peening. I would like to shot minimum 50 Almen strips and then measure the variation in arc height.

1. The question is what tolerance to set on the variation. Is 0.2mm (0.007874") a normal value?

2. What value on capability is recommended to set on a new machine? I think >2 is what we at least need to set as a minimum to get a stable process. What do you think?

Johan,
I like your concept and think that your initial proposals, 0.2mm and capability of >2, is reasonable.Let's see what others think. I'll mention this at our next AMECSE meeting Jan 26, 2010 in Asilomar when we review AMS 2430 and AMS 2432.

As you may know, Electronics Inc. has provided premium grade Almen strips for many years. In addition to testing the SAE required parameters of length, width, thickness, hardness and pre-bow (flatness) we also do performance testing. The following link will show you the distribution of arc heights for a common setup. You should expect to get similar results when you perform your own tests. Please let me know of your results.
http://www.electronics-inc.com/uploads/StripTesting.pdf