How to approve a factory material substitution
Keep the agreed material or component in place until you have compared the proposed substitute, tested representative samples and reviewed the compliance impact. Approve the exact change and affected batches in writing before use. Ask Cambridge China Bridge to coordinate the factory evidence and samples.
Put the proposed change on hold
Tell the factory to keep the agreed specification until you issue written approval. Ask why the change is needed, whether the original remains available, and whether any substitute has already been bought or used. If production has started, ask the factory to identify and separate affected goods.
Request a change record showing the original and proposed manufacturer, material grade or component code, supplier, intended batches and revised specification. Agree who pays for samples, testing and any rework before proceeding. Our bulk production guide covers the underlying sample and inspection controls.
Ask for evidence of equivalence
Ask for a comparison against your specification, supported by original datasheets, material certificates and relevant test reports. Include dimensions, composition, tolerances, operating limits, finish and compatibility as applicable. Have the factory identify differences and missing evidence rather than simply describe the substitute as equivalent.
Judge equivalence by the intended use. A connector may fit but run hotter; a fabric may match in colour but shrink differently; an adhesive may bond initially but fail after cleaning. Check that reports identify the proposed grade or component and relevant test conditions. See how to verify product test reports.
Test the substitute in the finished product
Agree test methods and acceptance criteria before reviewing results. Obtain samples made with the proposed production material or component, using the intended process. Compare them with the original under the same conditions, including assembly, normal use and foreseeable stresses such as heat, moisture, washing or repeated movement.
A loose component test may miss a problem created by the assembly. Ask the laboratory or technical reviewer which finished-product tests the change affects, and record the reasons for repeating or retaining existing tests. Keep sample identities linked to their materials and reports. Our laboratory sample traceability guide explains that handover.
Review compliance separately from performance
UK government guidance for products under the UKCA or CE regimes in Great Britain states that manufacturers remain responsible for assessing product risks, identifying relevant requirements and documenting how they are addressed. A factory's equivalence claim should therefore be reviewed alongside the product's compliance evidence.
Ask your compliance reviewer to assess the changed composition, ratings and intended use against the relevant requirements. Request a written decision on further testing and updates to risk assessments, technical documents, declarations, labels or instructions, as applicable. Do not treat your commercial acceptance as compliance clearance. See modified or rebranded product compliance.
Approve the exact change and verify its use
Record approval or rejection against the change record. An approval should name the substitute, specification revision, supporting reports, approved sample and affected orders or batches. State any conditions, the authorised approver and whether approval is temporary or continuing. Avoid an open permission to use anything the factory considers equivalent.
Send the approved revision to production and inspection staff. Ask for records linking incoming materials or components to finished batches, and check production against the approved change. If an unapproved substitute appears, hold release, establish its extent and assess it before deciding on rework or rejection. Retain the original specification and the change history.
Frequently asked questions
Can I accept a substitute described as equivalent?
Only after checking evidence against your specification, testing representative samples and reviewing compliance. Ask the factory to identify differences and obtain written approval before use.
Does a material certificate replace sample testing?
It can support material identity and properties, but may not show how the finished product behaves. Agree tests that address the changed material and its interaction with the assembly.
Do I need to repeat every product test?
Ask a competent reviewer to identify which tests the change affects. Record the reasons for repeating tests or relying on existing evidence; do not assume the original reports cover the substitute.
What if the factory has already used the substitute?
Hold release and ask the factory to identify and separate affected goods. Review evidence, samples and compliance before deciding whether to approve, rework or reject them.