Key takeaways
- Four documents are the minimum: a certificate of conformity for each lot, a material data sheet, a REACH chemical declaration, and the lot traceability rules.
- Lot traceability is the most expensive one to be missing: without it, a defective lot forces the recall of the whole stock holding instead of the lot actually concerned.
- The material data sheet has to state the temperature range and the measured Shore A hardness, not only the compound name. NBR is a family of materials, not a specification.
- Ask for a first-lot qualification sample before the supplier code is opened, and state on the first purchase order that the lot is a qualification lot.
Opening a supplier code for sealing products is not technically difficult. The time goes on paperwork, and most of that time is lost because the document list is sent in instalments instead of all at once.
Below is the minimum set commonly required at FDI factories, with the reason each item exists. Asking for the whole set at the start saves several weeks.
1. Certificate of conformity, one per lot
Not one blanket certificate covering the part number, but one certificate for each lot delivered.
It has to carry: the part number, the lot number, the quantity, the date of manufacture, and confirmation that the lot was produced to the approved specification. Signed or stamped by the supplier's quality department.
Why it exists: when a fitting position fails early, the first question is always which lot. Without a certificate per lot there is no answer.
2. Material data sheet
This is the document most often sent incomplete, because the supplier tends to send one line reading "NBR" and treat that as enough.
NBR is a family of materials, not a specification. Two NBR compounds that differ in acrylonitrile content differ markedly in temperature range and oil resistance. The data sheet has to state:
- the compound name and the compound manufacturer
- Shore A hardness, with its tolerance
- the continuous operating temperature range, and the short-term peak where there is one
- compatibility with the media groups
Without this sheet, every comparison between two suppliers is a comparison of names.
3. Chemical declarations
For a factory exporting to Europe, a REACH declaration on substances of very high concern is mandatory through the supply chain.
For parts going into electrical and electronic equipment, a RoHS declaration is needed as well.
The two declarations do not replace one another, and not every supplier holds them ready. Ask early, because this is the document the supplier has to request back up the chain from the compound manufacturer, and it takes the longest.
4. Lot traceability rules
To be established before buying: where the lot number is printed, on the part or only on the packaging, and how long it stays traceable after the pack is opened.
This is the most expensive item to be missing. A lot with a problem that cannot be traced puts the recall scope at the entire stock of that part number, plus every fitting position it has gone into since the last goods receipt. With traceability the scope narrows to that one lot.
The first qualification lot
Before the code is opened formally, order a small lot and state on the purchase order that this is a qualification lot.
That secures two things: the supplier knows the lot will be inspected closely, and the buyer has grounds to reject it without breaking the commercial agreement if the result fails.
What gets inspected is set out in incoming inspection of a seal lot.
What not to ask for
Consider dropping from the list: a quality management system certificate from the intermediate distributor, when the manufacturer already holds one; and a test report per lot for standard parts held in stock.
The longer the list, the fewer suppliers can meet it, and the ones that can will price that cost in. Asking for exactly the four groups above is enough for most fitting positions.
