Which statistical tool to use?



Hi everyone,

Here's the case:

We are manufacturing objects that has 4 identical plates on it and our client gives us the deviation from CAD.

I assume that their measurements are flawless and are on the same spot on each plate (each plate is machined identically and only 1 measurement per spot).

I would like to know how to test how accurate our machining is by comparing the variations between plates and between each object we produce. The target average is known and the acceptance range is fixed.