A nonconforming part reaches a customer, the customer catches it, and now there's a containment action, a root cause investigation, and eventually a decision nobody enjoys making: does this supplier keep shipping, and if so, under what conditions. A quality escape is different from an internally caught nonconformance in one important way — the failure wasn't just the supplier's process, it was also every internal check that was supposed to catch it before it left the building, and reconstructing that full picture is far easier when a supplier's history already lives in manufacturing QMS platforms with supplier modules that link a specific supplier to their nonconformance and re-qualification record, rather than scattered across files and institutional memory that walks out the door when someone changes jobs. Re-qualifying the supplier without also examining that second, internal failure treats only half the problem.
Containment first, root cause second, re-qualification last
The sequence matters more than it might seem. Containment has to happen immediately — identifying every other lot or shipment that might carry the same defect, at the customer, in transit, and in the organization's own stock, before anything else. Root cause investigation, ideally using 8D or an equivalent structured method, comes next, and it has to reach an actual process-level cause rather than stopping at the specific defective part. Only once containment is verified and root cause is understood does re-qualification become a meaningful exercise — re-qualifying before root cause is confirmed just re-approves whatever produced the escape in the first place, with extra paperwork attached. A shop that rushes this sequence to satisfy an anxious production schedule — running a re-qualification lot before containment is even confirmed complete — often finds itself back in the same conversation a few months later, except now with a second escape on the record and a customer asking why the first one apparently taught nothing.
What re-qualification actually needs to test
A real re-qualification doesn't just check that the specific defect from the escape doesn't recur in the next lot — it has to verify that the corrective action actually addresses the process condition that allowed the defect to happen, which usually means requesting evidence beyond a single clean sample. First article inspection on the corrected process, a run of several consecutive lots under heightened monitoring, and where relevant a review of the supplier's own internal controls that should have caught the issue before shipment, all belong in a genuine re-qualification. A single good part proves the process can produce a good part under close observation. It doesn't prove the underlying condition that caused the escape has actually been eliminated. For a dimensional escape traced to tooling wear, for instance, a legitimate re-qualification wants to see the wear-monitoring plan the supplier put in place, not just a first article that happens to measure within spec on the day an inspector is watching.
Setting the heightened monitoring period, and knowing when it ends
Re-qualification isn't a single pass-fail event — it's usually a defined period of elevated scrutiny that either confirms the corrective action held or reveals that it didn't. That period needs an explicit length and explicit exit criteria set in advance, not a vague sense that things will loosen up "once we're comfortable." A reasonable approach ties the heightened monitoring period to a fixed number of consecutive conforming lots or a fixed calendar window, whichever is more appropriate to the part's production frequency, with a documented decision point at the end rather than an informal drift back to standard sampling. Skipping this step is how a supplier ends up back on normal monitoring status simply because nobody remembered to formally close out the heightened period, which leaves the file looking like a decision was made when in fact nobody actually reviewed the evidence.
Deciding whether the relationship survives
Not every escape should end a supplier relationship, and not every escape should be forgiven with a corrective action and a return to normal monitoring status. The deciding factors are usually the severity of what escaped, how the supplier responded once notified — quickly and substantively, or slowly and defensively — and whether this is a first occurrence or part of a pattern that a scorecard would have shown coming. A supplier who responds to their first-ever escape with a thorough, verifiable root cause investigation is behaving exactly the way a good long-term supplier should under stress. A supplier whose response is thin, late, or minimizing, especially if it's not their first escape, is providing exactly the information needed to make the harder decision.
Closing the internal gap, not just the supplier gap
The part of re-qualification that gets skipped most often is the internal half — why did incoming inspection, or whatever internal check was supposed to catch this, miss it. Sometimes the answer is a legitimate gap in the sampling plan given the part's criticality. Sometimes it's a check that existed on paper but wasn't actually being performed consistently. Either finding needs its own corrective action, separate from whatever the supplier is doing on their end, because a supplier re-qualification that leaves the internal detection gap open just resets the clock until the next escape finds the same hole. An organization that closes the supplier's corrective action but never asks why its own sampling plan let a defective lot through is solving half the problem and quietly accepting that the other half will happen again, just with a different supplier's name attached to it next time.