When a BOM revision changes during component sourcing, reconcile the new requirement with existing stock and open orders. Freeze the change's effective scope first. Then identify which received parts and confirmed orders can serve the revised build. Send a new RFQ only for the remaining approved need. A revised design does not, by itself, confirm a supplier's acceptance of an order amendment.
Freeze the Change's Effective Scope
Start with the approved change record. Identify the previous and new BOM revisions, affected assembly variant, and the first build that uses the change. Keep the earlier release as history. Do not overwrite it with an updated spreadsheet bearing the same filename.
A change can apply to future builds while an earlier build still needs the original component. Ask the design owner to resolve that boundary. Record any permitted use of existing stock, qualification conditions, or customer restrictions exactly as approved.
The BOM scrubbing guide covers fitted states and quantity bases before an RFQ. This task begins after a requirement changes and supply activity already exists.
Build a Before-and-After Line Map
Keep a stable requirement ID for every affected line. Record the old manufacturer and complete MPN, the new approved manufacturer and complete MPN, and both required quantities. Show an unchanged part with a changed quantity as a change too.
Separate four cases: quantity increase, quantity decrease, part replacement, and removal from the selected build. A replacement can leave an obligation for the old component while creating a separate need for the new one.
Use the approved-alternative record where a decision permits another part. Do not infer approval from a supplier's cross-reference or an old acceptance for a different assembly revision.
Review Existing Supply Before Buying Again
List the affected material in its actual state. Distinguish received stock, confirmed open order quantities, unconfirmed quotations, and requested amendments. Keep each physical quantity or order line represented once.
Current State | Review for the New Build | Record the Outcome |
|---|---|---|
Received stock | Is this quantity available, acceptable and allocated to this build? | Eligible quantity and its stock reference |
Confirmed open order | Does the exact part and remaining quantity meet the new need and required date? | Eligible outstanding quantity and current confirmation |
Unconfirmed quotation | Is it still an option worth pursuing? | Offer only; no confirmed supply deduction |
Amendment or cancellation requested | Has the supplier accepted the specific change? | Pending until the applicable confirmation is recorded |
Old part no longer approved for this build | Is there another authorized use or a disposition decision? | Separate stock or commitment requiring action |
Check received and outstanding quantities carefully. An order for 500 pieces with 200 already received has 300 outstanding. Counting 200 on hand and the original 500 as future supply would double-count those receipts.
Microsoft's engineering change management documentation illustrates reviewing a change's impact across purchase orders, production orders and inventory. That is an example of a planning workflow, not a StockWake software feature or a claim that every ERP handles changes automatically.
Calculate the Revised Sourcing Gap
For one approved build requirement, calculate:
New sourcing gap = maximum of zero and: revised requirement minus eligible allocated stock minus eligible confirmed outstanding supply.
Use a common unit, such as individual pieces. Check eligibility for the selected revision, build and required date before subtracting a quantity. Do not use the entire warehouse balance when some units belong to another build or are on hold.
This is a sourcing-gap calculation. It does not calculate financial exposure, cancel an order or authorize use of a different part. A quantity-complete plan can still have unresolved acceptance or delivery conditions.
A Hypothetical Revision Reconciliation
Assume Revision A needed 600 pieces of one unchanged component. Revision B raises the requirement to 800 pieces for a specified future build. There are 150 acceptable pieces allocated on hand and 300 eligible pieces still outstanding on a confirmed order.
The revised sourcing gap is 800 − 150 − 300 = 350 pieces. The buyer requests 350 additional pieces, with the original references retained. The updated RFQ identifies any earlier request for the same need that it replaces. The 300-piece open order stays in the plan once. A new supplier quote does not become an additional confirmed supply quantity merely because it answers that RFQ.
Now consider a different line removed from Revision B. Its existing order still has 100 pieces outstanding. A request to cancel those pieces is pending. The buyer records zero new demand for that line and a separate 100-piece unresolved commitment. The record does not label the order cancelled before the specific amendment is confirmed.
These numbers are hypothetical planning inputs. They describe no actual inventory, purchase agreement or supplier response.
Send a Specific Change Request to Each Supplier
Identify the quotation or order reference and affected line. State exactly what you want changed: full MPN, quantity, shipment schedule, packaging or another agreed condition. Keep unchanged lines identifiable.
Ask the supplier to confirm the resulting order line and any revised conditions. Preserve the earlier document and the response together. A sent email, an internal approval or an updated BOM does not establish that the supplier accepted the requested amendment.
Check the NCNR quotation checklist where restrictions apply. Resolve the specific commercial question with the authorized reviewer. Do not assume that a design change creates a right to cancel, return or substitute material.
Close the Revision Loop
Update the sourcing record when an accepted amendment, receipt or approved allocation changes the plan. Keep received material separate from the remaining order balance. Refer residual old stock to its responsible owner for a documented use or disposition decision.
Before the next purchasing release, check that engineering, planning, purchasing and receiving use the same effective revision. Leave unresolved commitments visible. The practical result should be one current requirement map, a traceable supply plan, and a precise list of open actions.
Frequently Asked Questions
Should I Send the Entire Revised BOM to Every Supplier?
Send the information needed for each affected request, with clear revision and line references. Identify what the update replaces. Keep unaffected requirements distinguishable. If a supplier needs the full context, provide a controlled release rather than several conflicting spreadsheets.
Can an Open Order for the Old Part Cover the New Part?
Only when the approved requirement permits that exact part for the relevant build and the offered supply meets the conditions. Similar descriptions are insufficient. Until that decision exists, track the old-part commitment separately and keep the new-part sourcing need visible.
Should Pending Cancellation Quantities Be Deleted?
No. Retain the current order state and mark the requested change as pending. Record the supplier's applicable written confirmation before showing the amendment as accepted. A removed BOM line changes design demand; it does not document the commercial outcome.
What If Material Arrives During the Change Review?
Record the receipt against the correct order line. Reduce its outstanding balance by the same received quantity. Confirm the material's allocation and acceptance state before counting it toward the revised build. Do not count it as both received stock and future supply.
Does a Zero Sourcing Gap Mean the Build Is Ready?
No. It means the counted eligible quantities cover that requirement under the recorded assumptions. Confirm the delivery dates, documentation, acceptance conditions and current revision separately. Unresolved old-part commitments also remain action items even when the new build's quantity gap is zero.