What goes on a material substitution request?
Ask the factory for a written request comparing the approved and proposed materials, identifying affected stock and batches, and setting out validation, named approvers and release conditions. Link the decision to revised specifications before production proceeds. Cambridge China Bridge can coordinate this with its staff in China.
Identify the request and compare the materials
Give the request a unique reference and status. Record the factory, product and part references, order references, current specification revision, reason for substitution and proposed changeover point. State whether approval is sought for a bounded batch or a permanent specification change. Use this record alongside your repeat-order change control.
Attach a side-by-side comparison of the approved and proposed materials: manufacturer, supplier, grade, composition, finish and relevant properties. Include dated data sheets, material certificates, labelled samples and report references tied to the actual material lots. Identify missing evidence and explain every difference; a shared trade name or similar appearance is not proof of equivalence.
Draw the affected-batch boundary
Record the last batch using the approved material and the proposed first batch using the substitute. Identify raw-material lots, work in progress, finished goods, warehouse stock and shipments that could be affected. Include quantities from factory records, storage locations and the product or carton identifiers that distinguish each material.
Ask whether substitution has already occurred. If it has, record the earliest known use, supporting stock and production records, and any uncertainty. Agree segregation and hold instructions for uncertain stock. State how leftover material, mixed stock, rework and returns will be handled so the release boundary can be checked physically.
Define validation before testing starts
List what the change could affect: strength, fit, durability, appearance, chemical composition, manufacturing behaviour or packaging protection. For each concern, name the test method, acceptance criteria, sample selection, test provider and report reviewer. Include finished-product trials where assembly or processing could change the outcome. Use the substitute-material qualification guide for the wider assessment.
Explain which existing reports are being relied on and why they cover the proposed configuration; follow the test-report verification guide. For products within the UKCA or CE regimes in Great Britain, manufacturers must prepare a technical file. Ask the compliance reviewer to record whether the substitution calls for revised evidence or documents, and resolve gaps before release.
Name the people who can approve and release
Name the factory requester, buyer's technical approver, quality reviewer, compliance reviewer and commercial owner. Record each person's decision scope, required evidence and approval date. Roles may share an owner, but make the allocation explicit. A purchasing contact's agreement to a price change should not be treated as technical approval.
Separate permission to make trial samples from permission to use the material in production or ship goods. The written release should identify the request, approved material, covered batches, accepted report references, conditions, approving person and date. Record rejection or unresolved conditions explicitly. Silence, a sample receipt or an informal acknowledgement should not count as release.
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Update the specification and close the record
Attach the released specification revision and update the BOM, drawings, purchase-order attachments, inspection instructions and reference samples wherever affected. Record the effective batch and withdraw superseded production instructions. For temporary approval, state its end boundary and the return to the original material. For permanent approval, carry the revised specification into repeat orders.
Keep the request, evidence, decisions and release together. Ask the factory to acknowledge the revised documents and provide changeover records showing which material was used. Check the first released production against those records before closing the request. The factory substitution approval guide supports the approval decision; this request records its evidence and implementation.
Frequently asked questions
Is a supplier data sheet enough to approve a substitute?
Use it as supporting evidence. Match it to the proposed grade and material lot, compare relevant properties, and complete the agreed validation before written release.
Can I approve a substitution for a single batch?
Yes, as a practical approval arrangement. Identify the covered batch, exclude other stock, state the end boundary and confirm which material later orders should use.
What if the factory has already changed the material?
Record the earliest known use and trace affected stock and shipments. Agree a hold for uncertain goods, establish the batch boundary and assess the evidence before deciding their disposition.
Who should sign a material substitution request?
Name owners for technical, quality, compliance and commercial decisions. Identify who can issue the final written release and distinguish trial permission from production and shipment approval.