Guide
What is a supplier deviation request, and how is it different from a waiver or use-as-is?
A supplier deviation request is a written ask from the supplier, made before parts are built or shipped, for permission to depart from a specific drawing requirement on a limited quantity, without changing the drawing. A waiver covers parts already made that missed the drawing, and use-as-is is the buyer's own disposition of nonconforming parts it already holds. Mixing up the three is how one bad lot quietly becomes the new standard.
By Saola Manufacturing engineering team · Published · Updated
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When should a supplier file a deviation request instead of a waiver?
File a deviation request when the supplier knows, before the parts exist, that it cannot or should not meet a requirement. File for a waiver only when the parts have already been made and inspection has found them outside the drawing.
The distinction is about timing and about who is carrying the risk. A deviation is planned: the bar stock in the specified temper is unavailable, a finish line is down and an alternate chromate is proposed, or a tolerance turns out to be unreachable on the existing fixture. The buyer gets to weigh the change before any money is spent on parts. A waiver is reactive: the parts are sitting in a bin, the inspection record shows a miss, and the question is whether they can still be shipped.
The vocabulary comes from configuration management. ISO 9000:2015 defines a deviation permit as permission to depart from the originally specified requirements before realization, and a concession as permission to use or release a product that does not conform to specified requirements. Aerospace and defense buyers often say deviation and waiver; automotive buyers often say temporary deviation; ISO-based quality manuals say deviation permit and concession. The ideas are the same. When you write your own procedure, pick one pair of terms and define them on the purchase order so the supplier cannot read a concession as permission to keep building out-of-spec parts.
One practical test: if the supplier can still choose not to make the nonconforming part, it is a deviation request. If it cannot, it is a waiver, and the supplier should also owe you a corrective action, because a waiver means a process escaped.
How do a deviation, a waiver, use-as-is, rework and repair differ?
Deviations and waivers are permissions the customer grants; use-as-is, rework, repair, return and scrap are dispositions someone decides once a nonconformance exists. Only rework brings the part back to the drawing, so every other path leaves a nonconforming part in the field that needs a record.
The table lays the options side by side. The column that matters most is the last one: whether the drawing still describes the part you shipped. If it does not, the deviation or waiver number has to travel with the parts, on the packing list and the certificate of conformance, so that whoever investigates a field failure later can find it. The certificate of conformance guide covers how that reference should appear on the certificate itself.
| Path | Raised when | Who decides | Part matches drawing afterward? |
|---|---|---|---|
| Deviation request (deviation permit) | Before manufacture | Customer engineering and quality | No, for the approved quantity only |
| Waiver (concession) | After manufacture, before shipment | Customer engineering and quality | No |
| Use-as-is | After receipt or detection | Customer material review board | No |
| Rework | After detection | Supplier, to an approved method | Yes |
| Repair | After detection | Customer approval required | No, but made fit for use |
| Return or scrap | After detection | Either party | Not applicable |
| Engineering change | Any time | Drawing owner | Yes, to the new revision |
Who should be allowed to approve a part that misses the drawing?
Only the design authority can accept a departure from the design, which in practice means the customer's responsible engineer plus quality, not the buyer and never the supplier alone. A supplier deciding use-as-is on its own is shipping nonconforming product without permission.
Regulated industries make the same point explicit: a use-as-is or repair disposition needs approval from whoever owns the design, and customer authorization when the nonconformity departs from the contract. For a supplier building to your drawing, the design owner is you. US government contracts follow this logic; FAR 46.407 tells contracting officers to reject nonconforming supplies in most cases and allows acceptance of critical or major nonconformances only on technical advice that the item is safe and will perform, with the concurrence of the activity that owns the technical requirements; the same section tells them to discourage repeated tender of nonconforming supplies. Separately, FAR 46.101 sorts nonconformances into critical, major and minor. Commercial industrial buyers are not bound by these rules, but the structure is worth copying.
A workable internal rule for a commercial OEM is a short approval matrix. A buyer can sign nothing technical. The responsible design engineer signs for fit, form and function. Quality signs that the record is complete and that the corrective action is open. Any characteristic flagged as critical, safety-related or regulatory goes to whoever owns that requirement, for example the person who signs off pressure ratings or material compliance, and some of those should simply never be waived. Write the matrix down before the first request arrives, because the first one always arrives on the day the line is waiting for parts.
What should a deviation request form contain?
Enough for an engineer who has never seen the part to decide without a phone call: the exact requirement, the exact departure, how many parts, why, what it affects, and what stops it happening again. Anything vaguer gets approved on trust, which is the failure mode you are trying to avoid.
- Identification: part number, drawing number and revision, purchase order and line, lot or heat numbers, and a unique deviation number.
- Requirement and departure: the balloon number from the inspection drawing, the requirement as written, and the actual measured values, not “slightly over.” If the drawing is not ballooned yet, the ballooned drawing guide explains why it should be.
- Scope: a quantity or a lot list, never an open-ended date range on its own, plus the serial or date-code range if parts are marked.
- Cause: material, tooling, process, measurement or drawing ambiguity, with the evidence.
- Impact statement: which mating parts, functions and downstream operations (coating, assembly, test) could be affected, in the supplier's honest view.
- Containment and corrective action: how conforming parts are being separated now and what changes so the next lot conforms.
- Marking and traceability: how the affected parts or cartons will be labeled with the deviation number.
- Signatures: requester, and each approver from your matrix, with date.
The same fields work for a waiver on parts already made. A good waiver entry reads like this: “Balloon 14, bore diameter, drawing rev C requires 12.00 +0.05/-0.00; measured 12.06 to 12.08 on 40 of 500 units in lot 2611; cause: worn boring insert not caught at the mid-lot check; request: accept the 40 units for this PO only; containment: full sort of the lot completed.” Every word of that is checkable. Compare it with “bore slightly oversize, functionally OK,” which tells the approver nothing and pushes the decision onto a guess.
Which mistakes turn a one-time deviation into a permanent problem?
The biggest one is approving the same deviation repeatedly instead of either fixing the process or changing the drawing. A deviation that is renewed every order has become an undocumented drawing revision.
The common mistakes, roughly in order of how much damage they do:
- Serial renewals. If the same characteristic needs a deviation on a second order, decide: either the tolerance is wrong and engineering should release a new revision, or the process is wrong and the supplier owes a real fix. The cost of tight tolerances guide helps with the first question.
- Open-ended scope. “Approved until further notice” means every future lot inherits the departure without anyone looking again.
- Approval by email reply. A “looks fine” from a buyer is not an engineering disposition, and it will not be found when the field failure investigation starts.
- No marking. Deviated parts mixed into stock with conforming parts are untraceable once they reach the assembly line.
- Waiving the gauge instead of the part. A thread that fails its go/no-go check gets waived because “the screw still went in”; that tells you about one screw, not about thread strength across the lot. See the go/no-go gauge guide.
- Skipping a new first article. If the deviation comes from a material or process substitution, the substituted process deserves its own first article, as the first article guide describes.
- Forgetting downstream operations. An oversize bore may still fit before anodizing and bind after it; ask what the coating does to the dimension before approving.
How should deviations be written into the RFQ and purchase order?
Put one short clause in the purchase order terms that says nonconforming parts may not ship without a written, numbered approval from you, and say who can give it. Then name the form and the traceability you expect, so the supplier knows the process before the first problem.
Example clause for a commercial purchase order, adapted to your own terms:
“Supplier shall not ship any product that departs from the drawing, specification or this purchase order without a written deviation or waiver approved by Buyer's engineering and quality, referenced by number. Requests shall identify part number and revision, affected characteristics by balloon number, measured values, quantity or lot, cause, containment and corrective action. Approved nonconforming product shall be segregated, labeled with the approval number, and the number shall appear on the packing list and certificate of conformance. Supplier shall not disposition nonconforming product as use-as-is or repair. Approval applies only to the quantity stated and does not change the drawing.”
In the RFQ itself, flag the characteristics you will never waive, such as sealing faces, threads on pressure-retaining parts or material grade, so the supplier can quote the inspection effort those need. If you use a sampling plan, say how a waiver interacts with it: a lot accepted under a waiver should not count toward reduced inspection. The AQL sampling guide covers how to write the sampling side.
What happens at Saola when a part misses your drawing?
Per the quality page, if a first-article measurement is out of tolerance the plant stops and tells you before a sample ships, with the measured value against your print, a proposed fix and a revised date. Nothing moves forward on a verbal okay.
A new part starts with a drawing review that returns a marked-up copy of your own drawing, which is the cheapest moment to raise a requirement that looks hard to hold, before any part exists. Each production lot ships with a dimensional inspection record checked against your drawing. On CNC milling work every GD&T call-out is measured and logged, and on CNC turning work thread fit is checked with go/no-go gauges before a lot ships. Dimensions your drawing marks as process-capability control points are checked more often through the run, and where no cosmetic standard is supplied the plant asks for one before running production. The quality page does not describe a deviation form of its own, so send yours with the purchase order. ISO 9001 certification is in progress and not yet issued; the full document list available today is on the quality page. To quote a part with your deviation and inspection terms attached, use the quote form.
Frequently asked
Is a deviation the same as an engineering change?
No. An engineering change revises the drawing for every future part. A deviation leaves the drawing alone and permits a departure for a stated quantity. If you approve the same deviation twice, it is a sign the drawing or the process needs changing instead.
Can a supplier rework parts without asking?
Rework that brings the part fully back to the drawing is usually allowed, provided the method does not affect other requirements. Re-machining a feature can change wall thickness, surface finish or coating coverage, so many buyers require approval of the rework method, and repairs that leave the part outside the drawing always need customer approval.
Should deviated parts be priced lower?
That is a commercial decision separate from the engineering one. In US government contracting, FAR 46.407(f) requires an equitable price reduction or other consideration when supplies with critical or major nonconformances are accepted; for minor ones the contract need not be modified unless the supplier's savings exceed the cost of processing the change. Some commercial buyers copy that approach. Keep the price discussion out of the engineering approval so it does not bias the technical answer.
How long should deviation records be kept?
As long as the parts can be in service, and at least as long as your other quality records for that part number. The record is most valuable years later, when a field return has to be traced back to a lot.
Does a deviation need a new certificate of conformance?
The certificate should still be issued, but it must reference the approved deviation or waiver number instead of declaring full conformance. A certificate that claims full conformance on parts shipped under a waiver misstates what was shipped.
Sources
- ISO 9000:2015 Quality management systems, fundamentals and vocabulary, International Organization for Standardization, 2015
- FAR 46.101 Definitions (critical, major and minor nonconformance), Federal Acquisition Regulation, accessed 2026
- FAR 46.407 Nonconforming supplies or services, Federal Acquisition Regulation, accessed 2026