An auditor walks up to your NC machining station and asks a simple question: "How do you know when a part is done?" The question seems straightforward, but the way you answer—and the evidence you can point to—reveals whether your operation actually follows a defined quality system or runs on assumption and experience. This moment, repeated across dozens of questions throughout an ISO 9001 audit, is where compliance becomes real.
Auditors are trained to ask behavioral and process-oriented questions because those questions cut through documentation to the actual practice. They are not interested in theory; they are interested in whether your people follow the system you have designed and whether that system reliably prevents nonconformances. The questions they ask are predictable enough that preparation is possible, yet varied enough that canned answers ring hollow. Understanding the patterns and intent behind audit questions helps you prepare your team to answer clearly and confidently.
Questions About Process Definition and Control
An auditor will ask: "How do you know what this part is supposed to look like?" This question is designed to verify that your design or engineering specifications are available at the point of work and that your production team actively uses them. The answer should be specific: "We have the print at each machine, we verify the print matches the customer purchase order, and we have a first article inspection before production starts." If the answer is "We've been making this part for years; the operators know what it's supposed to be," you have just signaled that your system relies on tacit knowledge rather than documented control, and that is a finding waiting to happen.
Related questions will probe how you manage changes to processes. "If a customer changes the tolerance on this dimension, how do you know?" "How do you notify the floor that a process has changed?" "What happens to parts that were made under the old specification?" These questions test whether you have a change management system and whether evidence exists that the system worked when changes actually occurred. An auditor may ask to see a change log, review how old parts were dispositioned, and interview operators about whether they were aware of the change. Small shops often discover that changes happen informally—a call from the sales team, a quick email, a post-it note at the machine—but there is no formal record.
Questions About Evidence and Records
No topic generates more audit findings than records management. "Can you show me the inspection record for this lot?" If you cannot produce it quickly, the auditor will note that nonconformance evidence cannot be established. If you produce it but the handwriting is illegible, the signature is missing, or the date is blank, the auditor will document that the record is incomplete. If the record exists but shows that a nonconformance was detected and there is no evidence of investigation or corrective action, that is a separate finding.
Auditors will ask about calibration. "When was this gauge last calibrated?" "What happens if a gauge is out of calibration when parts have been inspected?" "Show me the record of an out-of-tolerance calibration and what you did about it." Many shops maintain calibration schedules but struggle with the protocol for handling parts inspected with an out-of-spec tool. The answer cannot be "we checked the parts again with a good gauge." The system must address the risk: was the part already with the customer, and how was the customer notified? This requires evidence—a memo, an email, a meeting record—that the question was asked and answered.
Traceability questions probe lot and serial tracking. "If a customer calls and says 'I have a problem with your part from January,' how would you trace this part back to your production record, and how would you identify all other parts made in that run?" If your answer involves searching spreadsheets or asking multiple people, you do not yet have a strong system. If you can point to a lot traveler, a first article record, and an inspection log all linked to a purchase order, you have demonstrated traceability.
Questions About Nonconformances and Corrective Action
An auditor will select a recent nonconformance record at random and ask: "Tell me about this one. What happened? How did you investigate? What corrective action did you take, and how do you know it worked?" This is the moment your CAPA (corrective and preventive action) system is truly tested. A nonconformance record that says only "scrap" or "rework—dimension out of print" with no follow-up demonstrates a reactive, firefighting approach. A nonconformance record that includes the 5-Why analysis, the root cause, the corrective action assigned to a responsible person with a due date, and evidence that the action was completed and verified shows a mature system. The auditor may follow up: "Why did this happen?" and "What would you do differently next time?" If you cannot answer beyond "the operator made a mistake," you have not identified a system issue that warrants control.
Preventive action questions are more forward-looking. "Have you identified any risks that could lead to nonconformances, and what have you done to prevent them?" This is not a gotcha; it is an assessment of whether you have a risk mindset. You might answer by pointing to your control plan for a high-risk process, your supplier scorecards, your failure mode analysis, or your management review records showing that risks were discussed and mitigated.
Questions About Suppliers and Purchased Product
If your operation depends on purchased material or services, the auditor will ask: "How do you choose and evaluate suppliers?" "What criteria do you use to assess whether a supplier can meet your requirements?" "Do you check incoming material, and if so, what are you checking for?" The answer should reference a documented supplier approval process, scorecards or periodic reviews, and a clear incoming inspection protocol. If you reply "The supplier is certified by their customer; we trust them," the auditor will probe further: "And if they fail? Show me the record of an issue with a supplier and what you did about it."
Questions About Training and Competence
Auditors routinely ask: "How do you know this person is trained to do this job?" You should be able to point to a training matrix, a training record with dates, and evidence (a test, a sign-off by a supervisor, a practical observation) that the person is competent. If you answer "they've been here for five years," the auditor may not challenge it, but you have again revealed that your system relies on tenure rather than documented competence verification.
The common thread across all these questions is the same: your system is not your manual or your procedure library. Your system is what your people actually do, day after day, and the evidence that they do it. An auditor who visits qms2go.com/manufacturing to research audit focus areas often encounters this pattern: shops with good intentions and decent documentation but with a gap between paper and practice. Narrowing that gap is the work of audit preparation and, more importantly, the discipline of daily management review.