A certificate of conformity arrives with a delivery, gets filed, and is assumed to mean the goods were checked and are correct. Sometimes that is what it means. Frequently it means something considerably narrower.
What the term usually covers
A certificate of conformity is a statement that the goods conform to something. The critical question is to what, and on what basis. Three broad possibilities:
- Conformity to the order. You ordered this size and this quantity, and that is what was sent. Genuine, useful, and says nothing about performance.
- Conformity to a specification, based on inspection. Dimensions were measured against the drawing and passed. Better, provided the inspection was real and you know what was measured.
- Conformity to a standard. Meaningful if the standard is named and relevant. Less so if it is generic.
Those cover very different ground and all get called the same thing.
What a certificate usually does not cover
- Fitness for your application. Nobody can certify that without knowing the application, and if it is not described in your order, it is not covered.
- Service life. Almost never stated, for the reasons discussed in our warranty article — it depends on conditions the supplier does not control.
- Performance under your process conditions. Tension, speed, temperature, handling — all yours.
- Anything about future deliveries. A certificate covers a batch. It is not a standing commitment.
Reading one properly
Four things to look for, in order:
- Does it name what was conformed to? A drawing number, a specification reference, an order number. If it says “conforms to specification” with nothing identified, it commits to nothing identifiable.
- Does it say what was checked? “Dimensions verified” is weak. “Bore, traverse width and core diameter measured, n=5, results attached” is strong.
- Is it dated and tied to a batch? An undated certificate has no relationship to any particular delivery.
- Is it signed by somebody accountable? A name rather than a printed company footer.
What to ask for instead
If you want documents that actually help:
- Inspection results for the critical dimensions, even a short list. Discussed in the context of first-article inspection, and worth requesting per delivery, not just once.
- Material identification at grade level, which supports any substance declaration you need to make.
- A named contact for quality questions, which is worth more than any certificate.
- Commitment to notification of change — the item that prevents drift, and belongs in your quality agreement.
Certificates to be cautious about
- Documents with no batch reference, no date and no named individual
- Certificates referencing standards that do not apply to the product type
- Anything implying third-party certification where there is no third party — see the note in our article on substance declarations
- A certificate used to avoid answering a direct question
The filing question
Certificates are only useful if you can find them. Filed against the purchase order or the delivery, not in a general folder. When a question arrives it will be about a specific delivery, and a folder of unlinked certificates answers nothing.
What we provide
For our hollow board spools we can state what was made, to which drawing, and what we measured — with the results, not just a conclusion. We can identify material by grade and reference the batch.
What we will not issue is a certificate that sounds broader than what we actually did. A document that overstates is worse than no document, because it gets relied on.