OEM sheet metal supplier audit checklist

How to use it

Score each line with evidence, not impression. "Do you have a quality system?" is not a question; "show me the last three internal audit reports and the corrective actions that came out of them" is. If a supplier cannot produce a document during the visit, treat it as absent.

Section 1 — Process capability

What machines exist, what is their condition, and what tolerance can they actually hold on the part family you are buying? Ask for a first article report from a comparable part, not a capability brochure. Check that the press tonnage, brake length and laser bed match the drawing you sent, not the largest machine on site.

Section 2 — Tooling control

Who owns the tool, where is it stored, how is it maintained, and what is the record? A supplier who cannot show a tool maintenance log is telling you the tool will fail without warning. Ask to see a die being set and a first-off check.

Section 3 — Quality system and inspection

Look for a calibration register, a gauge R&R where measurement matters, non-conformance records and a corrective action loop that closed. Ask how a dimensional non-conformance is quarantined.

Section 4 — Coating and finish

If coating is in scope, ask for the pretreatment line chemistry records, DFT measurement records, adhesion test results and the salt-spray scope. If coating is subcontracted, ask who does it and how it is controlled.

Section 5 — Documentation and traceability

Mill certificates linked to the batch, first article reports, PPAP where required, packing lists and a certificate of conformity. Ask to trace one shipped batch back to the heat number.

Section 6 — Capacity and commercial

What is the current loading, what is the lead time at peak, what happens in a capacity crunch, and who is the escalation contact? A supplier with no capacity answer is a risk regardless of quality.