Factory material changes on repeat orders
Hold production using the substitute until you have compared it with the approved specification, tested the affected properties and reviewed the compliance evidence. Approve the exact change in writing, define its scope and issue revised production documents. Cambridge China Bridge can coordinate factory evidence through its staff in China.
Get a change request before agreeing
Ask the factory to identify the current and proposed material or component, including maker, grade, part reference, composition and relevant data sheets. Record why it wants to change, which orders are affected, and any effect on cost or delivery. Treat “equivalent” as a claim to investigate. Tell the factory to hold affected production pending your written release.
Build a comparison against the approved specification, highlighting every difference and anything still unknown. Include changes to the upstream supplier or manufacturing process, even if the part name stays the same. Our product specification guide covers the underlying specification; this change request should record the proposed departure from it.
Agree tests that address the change
Have your technical reviewer identify what the substitution could affect: fit, strength, wear, colour, heat resistance, chemical composition or interaction with neighbouring parts. Agree the test methods, acceptance criteria, sample selection and reviewer before testing. Include customer specifications and intended use. A visually identical component can behave differently in the finished product.
Use traceable samples of the proposed production material and compare them with the approved version under the same conditions. Test the assembled product where interfaces matter, such as a seal with its housing or an adhesive with its substrate. Ask a suitable laboratory to explain any testing gaps. Follow our laboratory sample traceability guide when sending samples.
Review the compliance impact separately
For products within the UKCA or CE regimes in Great Britain, government guidance states that manufacturers remain responsible for assessing product risks, identifying relevant requirements and documenting how they are addressed. Treat the substitution as a prompt to review that assessment, rather than assuming the previous order's evidence still covers it.
Ask the responsible compliance reviewer to map the change against existing reports, declarations, risk assessments, labels and instructions. Request a written conclusion identifying evidence that remains applicable, additional checks needed and documents to revise. Agree targeted or wider retesting with the reviewer based on the change. Our test report verification guide explains how to check the reports themselves.
Make approval specific and bounded
Keep sample approval separate from permission to start production. The written decision should identify the substitute, affected product and order, supporting test results, compliance review, outstanding conditions and authorised approver. State whether approval covers only the named order or future repeat orders. A purchasing acknowledgement or discussion of price should not serve as technical release.
If evidence is missing or a test fails, keep the affected production on hold and request further evidence, a different substitute or the original specification. If goods have already been made, ask the factory to segregate them and identify affected batches. Record any concession separately, with its limits and reviewer; do not silently rewrite the specification to match failed goods.
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Revise the specification before production
After approval, issue the revised specification, drawings and BOM as applicable. Update material identity, approved supplier, acceptance criteria, sample references and inspection instructions. Mark superseded documents clearly and retain them with the change record. Ask the factory to acknowledge the revision and confirm that purchasing, production, subcontractors and inspectors are using it.
Define the batch where the approved change begins, how old stock will be separated and how incoming material identity will be checked. Use a pre-production sample from the changed materials as the production check, following making bulk production match the sample. Cambridge China Bridge's staff in China can coordinate sample collection and factory acknowledgements; the buyer retains its technical and compliance approval. For ongoing monitoring, see our guide to tracking supplier performance on repeat orders.
Frequently asked questions
Can a factory use an equivalent material without approval?
Set a written no-substitution instruction in the order. Require evidence for the proposed equivalent and an explicit production release from your authorised approver.
Does every material substitution need full retesting?
Agree the scope with a competent technical and compliance reviewer. Test affected properties and interactions, and document why existing evidence remains applicable or needs replacing.
Is approving a replacement sample enough?
Keep sample acceptance separate from production release. Record the exact substitute, test evidence, compliance conclusion, approval scope and specification revision.
What if the factory has already used the substitute?
Hold release of affected goods, request segregation and batch traceability, and assess the actual configuration. Decide on further testing, rework or rejection before shipment.