Slyder,
Perhaps it would help me understand the issue better if I knew the answer to this: Are you designing a part and looking to come up with the proper intensity range or are someone who is performing the shot peen processing of a part?
"Why at the lower end of the A scale would you allow the strip arc height maximum to grow larger than 30%? In fact at 4A the arc height % increase calculates to 75% if .003 is used." Reason is process capability. variation in the strips themselves and the process need at least .003 or greater tolerance spread.
The scaling you mention of 3x is theoretical, its not something a shot peen service supplier like myself would consider at all. All I can do is see what the desired intensity range is on the engineering drawing. It might be shown as 4A or it could be shown as something like: .004-.006A, .004-.007A, .004-.008A etc.. It is better when the exact range is on the drawing as it leaves no doubt as to the expectations.
Once a peening process is established via the saturation curve and an intensity value is declared, in production that intensity value has to be repeatable within +/-0.0015" of the declared intensity value and be within the specified limits of the engineering drawing. The more locations that need intensity to be both determined and verified the more difficult both become to accomplish. Bottom line is it best if the engineering drawing states the range and not have to rely on the specification default.
