How to manage bill of materials revisions
Manage BOM revisions by never editing a released bill of materials in place. Create a new revision with its own identifier, date, reason and approver, and set the date it takes effect. Decide what happens to open work orders and to stock of any part that is dropped. Keep every old revision readable, because jobs built against it must still be traceable and costed.
By Arunkumar V, CTO · 03 November 2026 · 2 min read
- how to manage BOM revisions
- bill of materials revision control
- BOM change management
- engineering change in ERP
Why a revision is a new record, not an edit
A bill of materials is used by purchasing, the store, the shop floor and costing at the same time. If someone edits the released BOM to swap a fastener, a work order released last week now disagrees with its job card, the material issued no longer matches the list, and the cost roll-up for last month's jobs changes after the fact. A new revision keeps the old one exactly as it was, so every job points at the list it was built from.
This is the same principle as an immutable stock ledger: history is never overwritten, only added to. It also makes a recall or a customer query answerable years later.
What to record on each revision
The revision header is the part most shops leave blank, and the part that answers questions later. Print the revision on every job card so the operator can check it against the drawing. Record at least the following.
- Revision identifier, such as A, B, C or 01, 02, 03, with a suffix for drafts.
- Date created and date effective, which may differ.
- Reason for the change in one plain sentence, such as a supplier discontinuation or a customer drawing update.
- Who requested it and who approved it.
- The customer drawing or specification number it corresponds to, where there is one.
- What to do with open work orders and old stock: use up, rework or scrap.
Handling open work orders and old stock
An effective date tells the planner which revision a new work order should use. Work orders released before that date normally finish on the old revision unless the change is for safety or a customer rejection, in which case they are stopped and reissued. Write the decision on the revision so nobody has to guess.
Stock of a part the new revision drops needs a decision too: use it up on the last old-revision jobs, rework it, return it or scrap it. Tell purchasing on the day the revision is approved so no further orders are placed for the dropped part.
How to raise a new BOM revision
- Step 1
Copy the current released BOM into a new draft revision with the next identifier.
- Step 2
Make the component, quantity or scrap changes on the draft only, and write the reason on the header.
- Step 3
Run the cost roll-up on the draft and compare it with the current revision.
- Step 4
Get the change approved and record the approver, the effective date and the rule for open work orders.
- Step 5
Release the new revision, mark the old one as superseded but readable, tell purchasing and the store, and reprint affected job cards.
Where ZMOS fits
ZMOS holds bills of materials with revisions, scrap allowances and cost roll-up, and the audit log records every change with who made it. Work orders carry routing steps and print job cards with a barcode, so the revision used on a job is on the card. It is designed for sheet-metal, machining and fabrication shops of 10 to 50 people. If you need engineering change management with CAD integration and multi-level approval chains, that is beyond a small-shop ERP. See BOM and production in ZMOS.
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Inside ZMOS
What is the difference between a BOM revision and a BOM version?
Most shops use the words interchangeably. Where a distinction is made, a revision keeps the part interchangeable with the old one, while a new version or part number is used when the change breaks interchangeability. Pick one meaning and document it.
Should I create a new part number instead of a revision?
Create a new part number when the changed part cannot replace the old one in service, in stock or in a customer's product. Use a revision when it still can.
How do I handle a BOM change while a job is half built?
Decide per change. If the change is cosmetic or supplier-driven, finish the job on the old revision. If it fixes a defect or a customer rejection, stop the job, record the parts already made, and reissue the remainder on the new revision.
Does the product cost change when the BOM revision changes?
Usually, since components, quantities or scrap allowances changed. Run the cost roll-up on the new revision before release and compare it with the old one. If the cost moved materially, sales needs to know before the next quote.
See it on your own stock and jobs
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