Guide
How to qualify a Mexican machine shop properly
Updated
Qualification is often reduced to asking whether a supplier is certified, which is close to the least informative question available. These checks take longer and tell you something.
Talk to a specialist What each qualification check actually proves, how origin differs from shipment, and why this search returns the wrong companies.
Start with the drawing, not the supplier
Send a real drawing with real tolerances and ask what they would question. A shop that comes back with sensible queries about datums, finishes or gauging is reading it; one that returns a price immediately may not be.
The quality of the questions you get is the single best early signal, and it costs nothing to obtain.
Read the certificate properly
A certificate names a standard, a scope and an audit date, and is issued by a body. Ask for all four and verify with the issuing body rather than accepting a PDF.
Then read the scope. A scope covering assembly does not cover machining, and scopes are frequently narrower than the logo on a website implies.
Require a first article
A full dimensional report against your drawing, not a statement of conformance. It proves this part was measured against this drawing, and it exposes any tolerance you specified that they cannot actually hold.
Ask separately about inspection frequency in production, because a good first article followed by no in-process measurement is a common pattern.
Ask about capacity share
What percentage of their capacity would your work represent? Too small and you are deprioritised whenever a larger customer calls; too large and you have created a dependency that will hurt you both.
It is a question few buyers ask and most suppliers answer honestly, and it predicts more about your next two years than the price does.