TECHNICAL GUIDE / 2026-10-02
Short answer. A suspected nonconforming lot should be identified and held under the buyer's quality procedure. Compare the result with the correct product specification and method, preserve a traceable sample, notify the supplier and document any retest or disposition. Do not release it by selecting a convenient passing number.
Confirm what failed before drawing a conclusion
An apparent failure may involve chemistry, grading, magnetic content, packing identity or another agreed parameter. First verify the exact product, lot, order sheet revision, unit and test method. A result from an F36 sample cannot be judged against a P36 sheet; a reference value on a public PDS may not be the agreed order limit. Check the laboratory record and sampling chain before telling production that the material is acceptable or rejecting the supplier.
The affected lot should be identifiable and held according to the plant's procedure. Record how many bags or bulk units are involved and whether any portion has already entered production. If several lots were mixed, identify the affected production batches. These facts allow the buyer to make a proportionate decision and prevent a narrow test issue from being turned into an unsupported claim about all material from a supplier.
| First check | Purpose |
|---|---|
| Product and lot | Identifies the material at issue |
| Specification revision | Shows the actual accepted limit |
| Method and unit | Tests comparability |
| Material location | Prevents unintended use |
Preserve the original result and sample
Keep the first test report, raw observations, instrument or method reference and sample identification. If the supplier requests a retest, agree which retained sample, laboratory and method will be used, and what result would change the decision. A retest is a planned investigation, not a repeated search until one reading passes. If the buyer's method is at issue, correct it transparently and document the reason.
Review how the sample was drawn from the shipment. A convenient scoop from one damaged container may not represent a large lot, while a mixed sample can conceal a problem in one sublot. Use the contract and quality plan to determine the next sampling step. Record both original and retest values. Deleting an inconvenient result weakens the evidence for buyer and supplier alike.
| Evidence | Keep |
|---|---|
| Initial report | Original measured result |
| Sample chain | Where and how material was taken |
| Retest plan | Method, sample and decision rule |
| Supplier response | Technical explanation and corrective action |
Choose a disposition under authority
Possible outcomes may include rejection, replacement, rework, a controlled trial or conditional acceptance, but the right option depends on the contract, application and buyer's quality authority. A supplier should not unilaterally downgrade a limit after delivery, and a production team should not silently use held material because it is urgently needed. If a deviation is accepted, record the affected lot, conditions, approver and any customer notification requirement.
Separate material conformance from finished-product impact. If part of the lot was used in a wheel, belt or refractory batch, inspect those products under the relevant procedure. A failed raw material value does not automatically prove every finished item failed, but it may trigger traceability and testing. Likewise, one apparently acceptable finished test does not erase a contractual material failure. Each layer needs its own documented decision.
| Decision layer | Authority question |
|---|---|
| Raw material | Does the lot meet the order sheet? |
| Production impact | Which outputs used it? |
| Commercial disposition | Who approves replacement or concession? |
| Future supply | What corrective action is required? |
Use the case to improve the next order
After disposition, review whether the specification, sample plan, label or communication contributed to the problem. If buyer and supplier used different test methods, resolve that in the next technical sheet. If a custom product was delivered under a generic code, create a distinct item identity. Keep the corrective action attached to the exact lot and agreed limits so future staff can see what changed.
When reporting a concern to CHAOYAN, send the model, lot, purchase sheet, complete test result, method, sample chain and affected quantity. The team can investigate against the supplied material record. Avoid vague messages such as 'your brown fused alumina is bad' without the evidence needed to find the issue. A precise report supports a faster, fairer solution and protects the buyer's process from a repeat mismatch.
Selection guidance
Hold the identified lot, compare against the agreed technical sheet and preserve the complete evidence set. Decide retest and disposition under the buyer's authority before releasing material.
Common mistakes
- Judging the result against a public reference instead of the signed order limit.
- Retesting repeatedly without a pre-agreed rule.
- Using held material because production needs it urgently.
- Treating one lot problem as proof about every supplier product.
Frequently asked questions
Can a batch be accepted after a failed test?
Only through the buyer's documented quality and contract process, with the specific lot, risk and approval recorded. This article does not grant a general waiver.
What should be sent to the supplier?
Send the exact model, lot, order specification, method, original result, sample history and quantity affected.
