Key takeaways
- A deviation is permission to depart from a requirement for a defined scope. A concession is the same idea applied to parts that already exist.
- Every concession needs a part, a quantity, a non-conformance, a risk assessment and an expiry.
- The customer approves a departure from the customer drawing. The supplier cannot approve its own concession on a customer requirement.
- Track concessions by part number and cause. A repeating concession is a design or process problem, not a paperwork routine.
Deviation, concession and waiver
The words are used differently between companies, so agree the meaning in the quality agreement. In general, a deviation is a planned departure from a requirement before or during production. A concession is a permission to use or ship material that does not meet the requirement. A waiver is often the customer's written release from a requirement for a stated quantity or period.
The common thread is that the part does not meet the drawing or the specification, and someone with authority decides it is acceptable for a defined use. That decision needs a record, because the next inspector will see the same non-conformance and needs to know it was assessed.
A concession is not a drawing change. A drawing change alters the requirement for all future parts. A concession applies to a known quantity and expires. If the same departure is needed again and again, the drawing is the wrong document.
When a concession is the right route
A concession is reasonable where the non-conformance is understood, the function is not affected and the customer agrees. A cosmetic mark on a hidden face, a hole at the edge of tolerance that still clears the fastener, or a plating thickness slightly below the nominal but above the functional minimum can fall into this group.
It is not the right route for an unknown cause. If the supplier does not know why the parts are out, a concession ships the symptom and leaves the cause in the process. It is also not the right route where a safety characteristic is affected, unless the customer has the technical authority to accept the risk in writing.
The decision should be based on evidence. Measure the non-conformance, state the worst case in the lot, and check the effect on fit, function, life and any regulatory requirement. An opinion without a measurement is not a risk assessment.
Consider the end use as well as the drawing. A busbar with a slightly reduced cross-section may carry the current but run hotter, and the temperature rise may affect a joint or a cable. A cosmetic mark on a visible panel may be acceptable to the engineer and unacceptable to the brand owner. The concession should reflect the user, not just the specification.
What a concession request should contain
A complete request identifies the part, drawing revision, lot, quantity and the exact requirement that is not met. It states the measured condition and the specification limit. It explains the cause if known, and the containment that prevents a wider escape.
It then sets out the risk assessment. What is the effect on assembly, performance, corrosion, fatigue, electrical contact and appearance? Is there a test result or a calculation to support the view? Is there a compensating control, such as a 100 per cent check on the affected feature?
Finally, it names the requested disposition: use as is, rework, repair or sort. Each has a different risk. Rework can introduce a new defect, and repair can change the part beyond the drawing. The request should say which one is proposed and why.
The decision rows
The table sets out the choices that a concession discussion usually turns on. The right answer depends on the part, but the questions are consistent.
| Option | What it means | What the record needs |
|---|---|---|
| Use as is | Accept the parts with the non-conformance | Risk assessment, quantity and expiry |
| Sort | Inspect and remove the non-conforming parts | Sort criteria, sample, result and scrap record |
| Rework | Bring the part back to the drawing | Approved method, re-inspection and traceability |
| Repair | Make the part functional without meeting the drawing | Customer approval, method and limitation |
| Scrap | Reject the lot | Disposition record and replacement plan |
A concession that covers an open-ended quantity is a drawing change in disguise. Limit it to a quantity and a date.
Who approves, and how far the approval reaches
The supplier can approve a deviation from its own internal requirement. It cannot approve a departure from a customer requirement without the customer's written agreement. That includes a drawing dimension, a material specification, a test method and a labelling requirement.
Route the request to the person named in the quality agreement or the purchase order. A buyer's email is not always enough. For a safety or regulatory characteristic, the approval may need engineering and quality signatures, and in some markets a notified body.
Keep the approval with the shipment. The certificate of conformity should reference the concession, and the packing list should identify the affected quantity. If the customer receives parts with no reference, the concession looks like a hidden non-conformance.
Mark it, limit it, trace it
Concessioned parts need to be identifiable. That may mean a label, a coloured tag, a separate carton or a note on the certificate. The method should survive the warehouse and the assembly line, because the person who needs the information is not the person who approved it.
Set an expiry. A concession for 500 parts or 30 days is a control. A concession with no end date becomes a permanent undocumented requirement, and the next audit will ask why the drawing was never updated.
Trace the affected parts forward. If a customer finds a problem later, the concession record should let you identify which shipments contained the parts. That is only possible if the lot and quantity are recorded at the time.
The marking should be understandable to someone who has not read the concession. A tag that says use as is without the reference number creates its own non-conformance. Use a short reference that points back to the file, and keep the file accessible.
When the same concession keeps coming back
A repeat concession is a signal. Either the drawing is tighter than the process can hold, the process is not capable, or the inspection is rejecting parts that function correctly. Each has a different fix, and none of them is another concession.
Review concessions by part number and cause every quarter. If one feature accounts for most of the requests, take it to design review. The answer may be a tolerance change, a new tool, a process change or a change of supplier.
Close the loop with the customer. A concession that is never reviewed tells the customer that the supplier is managing paperwork rather than the process. A short review that leads to a drawing change or a tool fix is a better outcome for both sides.
The record to keep
File the request, the risk assessment, the approval, the shipment reference and the close-out. Link it to the non-conformance record and the corrective action if one was raised. The file should let a new quality engineer understand the decision without calling anyone.
Retention should match the product. A concession on a safety part may need to be kept for the service life of the product. A concession on a cosmetic feature may need a shorter period, but the customer contract decides.
The test of a good concession process is simple. Can you answer, for any shipment, whether it contains concessioned parts, what the departure was and who approved it? If the answer takes more than a few minutes, the process is not under control.
Review the concession file before the next audit, not during it. A short quarterly check of open, expired and repeat concessions catches most of the findings while there is still time to act.
Frequently asked questions
What is the difference between a deviation and a concession?
A deviation is a planned departure from a requirement, often before production. A concession is permission to use or ship parts that already do not meet the requirement. Companies use the terms differently, so define them in the quality agreement.
Can a supplier approve its own concession?
Only for its own internal requirements. A departure from a customer drawing, material specification or test requirement needs the customer's written approval, and sometimes engineering or regulatory sign-off.
Does a concession change the drawing?
No. A concession applies to a defined quantity or period. A drawing change alters the requirement for future parts. If the same concession repeats, the drawing or the process needs to change.
What should be on a concession record?
The part, revision, lot, quantity, the requirement that is not met, the measured condition, the risk assessment, the disposition, the approver, the expiry and the shipment reference.
Sources and further reading
- ISO 9001:2015, Quality management systems, requirements, clause 8.7 on nonconforming outputs
- IATF 16949:2016, requirements for concession and deviation permits
- AS9100D, Quality management systems for aviation, space and defence, clause 8.7
Qumek Quality Desk
Quality team
The quality team responsible for first article inspection, PPAP packs, supplier audits and the records shipped with production parts.
Facing a lot that may need a concession?
Send the non-conformance and the drawing. The quality desk will help structure the risk assessment and the approval route.
Discuss a concession