I just had a question from a former student that had an established shot peening process with a base saturation curve. Without changing the part setup they relied only on verification arc heights for every x-hours amount of machine operation.

The student said someone had "meddled" with the machine requiring them to move a nozzle back into place (proper distance & angle). They asked if that requires a new saturation curve or can they just do a verification arc height and carry on if they get the expected arc height?

I instructed per the [EI SPT] book a new saturation curve was required because the "meddling" and correction can be considered machine maintenance. I question how many people actually practice this.

To carry this question further: what if a machine setup had ALL parameters documented (including nozzle distance and angle) from what I'll call "Job A". After the machine has been running a different job and the machine is set back to the parameters for "Job A", is it acceptable to only perform a verification arc height looking for an expected arc value?

I asked the student to join the forum and view the discussion.
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Dave Barkley
EI Shot Peening Training