Step 6 of 8
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Writing the spec — what goes on the print
An annotated nitriding callout template a competent vendor can hit and an incompetent one will refuse, with the eight elements that turn a wish into a spec.
Step 6 of 8Distortion budget
Distortion in nitriding is small compared to quench hardening, but it is not zero. Typical numbers run 0.0005-0.002 inch per inch of length on long thin features, more on unsymmetric geometries. "Minimize distortion" commits the vendor to nothing. Put a number on the datum that matters and accept that the vendor may quote a finish-grind allowance to hit it.
Total flatness deviation post-nitride ≤ 0.05 mm across the indicated datum.
Quick check
A precision punch is 12 inches long with one flat reference face. The shop's gas-nitride vendor warns that "we can't guarantee less than 0.005 inch bow." Is that number reasonable, and what is the print's path to tighter?