A supplier developing a custom electrical housing for an automotive electronics plant in Malaysia proposes an alternative resin after its original material becomes difficult to source. The housing dimensions will remain the same. The supplier says the replacement can protect the launch date and asks for approval by email.
In this illustrative situation, engineering may see a material question, the buyer may see a supply recovery plan, and the program team may see a schedule decision. None of those views is complete. A resin change could affect performance testing, process settings, approved materials, cost, and the identity of parts already produced.
The problem is what happens between a promising supplier proposal and permission to use the changed part. A co-development change should have one controlled decision record, even when several functions hold different approval rights.
Establish the Baseline Before the First Change
At development kickoff, the program manager and engineering lead should identify the controlled product baseline: drawing and specification revisions, approved material or performance requirements, manufacturing site, key process assumptions, validation plan, and the intended production approval route. Supplier quality confirms which process controls and evidence must accompany release. Procurement links that baseline to the commercial agreement, including development deliverables, tooling commitments, and the mechanism for assessing change costs.
Record who may propose a change and who may approve its technical, commercial, and program consequences. Design ownership and intellectual-property rights may sit in separate agreements; they do not substitute for authority to release a changed production part.
For automotive programs, AIAG's March 2024 APQP third edition explicitly adds coverage of sourcing, change management, risk mitigation, and gated management. The point for procurement is practical: a change register belongs inside the development process, alongside design reviews and sourcing commitments, rather than appearing for the first time after a supplier submits an invoice. Source: AIAG, APQP 3rd Edition.
Make Every Proposal Traceable to a Decision
Formal change review is triggered when the supplier or buyer proposes a departure from the controlled baseline or existing authorization limits. Routine process adjustments within approved parameters can follow established controls instead. For changes involving materials, geometry, test requirements, tooling, production methods, critical sub-tier inputs, or manufacturing location, the required approval level depends on technical risk, customer requirements, the quality system, and the contract. A supplier's assurance that form and fit are unchanged is useful information; it is not a complete impact assessment.
The program manager or designated change coordinator opens a single record when a proposal requires formal review, before any affected production lot is released. The record should state the part and revision, originator, reason, proposed effective point, affected sites and inventories, and the decision needed. Engineering and supplier quality classify the technical exposure; procurement checks orders and contractual obligations. If changed material has already been made, the authorized quality team determines identification, segregation, and disposition under the applicable procedure.
Avoid a blanket rule requiring every change to repeat a full qualification. Equally, do not permit a supplier to decide unilaterally that no revalidation is needed. The applicable customer requirements, engineering assessment, contract, and quality system determine the route.
Review Three Consequences Together
Before anyone approves a proposal, ask the supplier for an impact package that addresses three distinct questions.
Technical evidence. Engineering defines the affected requirements and the tests or analyses needed to establish continued fitness for use. Supplier quality checks process risk, traceability, control-plan changes, and whether a revised sample or production-part approval is required. A CAD overlay alone cannot establish that a material or process substitution is acceptable.
Supply consequences. The supplier documents remaining old-revision inventory, work in progress, tooling status, available new material, changeover timing, and any mixed-revision risk. Operations assesses the ability to build and identify the correct revision at the consuming plant. The schedule should distinguish sample approval from readiness to produce at the required rate.
Commercial consequences. Procurement asks for a documented cost bridge: incremental tooling or nonrecurring engineering, testing, scrap or rework, logistics, and any recurring piece-price effect. Finance validates material assumptions where relevant. Procurement checks who caused the change and which contractual provisions allocate responsibility; neither the supplier's quotation nor the buyer's preference automatically settles liability.
Treat these as a connected decision. An attractive new piece price may be erased by requalification expense or an interruption during changeover. A faster technical solution may require a separately authorized commercial concession.
Use Separate Approval Rights, Then One Release Decision
Technical acceptance, commercial agreement, and production release answer different questions. Combining them into a casual email approval invites later disputes.
| Decision | Accountable function | Evidence before sign-off |
|---|---|---|
| Is the revised part technically acceptable? | Design authority and required engineering / supplier quality approvers | Approved revision, risk review, completed required verification and validation |
| Are the change costs and obligations agreed? | Procurement under delegated authority, with finance/legal as needed | Cost bridge, contract or purchase-order amendment, documented liability allocation |
| Can the changed part enter the intended build? | Authorized quality / program release owner; operations implements | Required customer approvals, production approval status, inventory/traceability plan, effective date or lot |
These are proposed operating roles, not a universal industry authorization matrix. The supplier may hold design authority while buyer or end-customer approval is still required. Before release, engineering, supplier quality, procurement, and program approvals must reference the same change identifier, approved revision, manufacturing site, and effective lot or date. Actual release authority must follow customer, regulatory, contractual, and internal requirements. If a required test or approval is outstanding, the team must record a hold or seek a formally permitted deviation through the authorized route. A pending purchase-order amendment cannot turn an unapproved part into an approved one.
AIAG describes Production Part Approval Process (PPAP) as a means of demonstrating that a supplier's production process can consistently meet engineering requirements during an actual production run at production rates. Where PPAP is applicable, the change decision must account for the required submission and customer approval level; it must not assume an engineering sample is sufficient. Source: AIAG, PPAP.
Close the Change Only After the New Revision Works
The supplier should implement against an approved effective date, lot, or serial-number break. Supplier quality verifies the required inspection, process-control updates, and traceability evidence. Operations checks that the plant is receiving and consuming the intended revision; procurement reconciles invoices, tooling charges, and purchase-order terms to the authorized commercial case.
The owner should close the technical change record only when required validation and approvals are complete, controlled documents match the released production configuration, the first applicable production evidence has been accepted, and no unresolved issue affects product conformity, traceability, or authorized release. Non-blocking financial, inventory, or contract follow-ups may remain open in a separate tracking record only with a named owner, agreed completion date, and documented handover approval. Assigning an owner does not resolve those obligations. A signed drawing alone is not closure. If the initial production results contradict the approval assumptions, the designated technical owner reopens the risk assessment and determines containment and next actions.
Return to the illustrative housing. A disciplined team may choose to test the alternative resin while maintaining the old approved route for production. It may negotiate material premiums without authorizing shipment of unapproved parts. Or it may reject the proposal when the validation window makes the supposed schedule saving unrealistic. All three outcomes can be sound; the evidence determines which one is.
Supplier co-development becomes controllable when every change has a traceable technical decision, a priced commercial consequence, and a verified production release.