Bills of materials change, that is normal and necessary. But a manufacturer usually has manufacturing orders already open, in progress or planned, when a BOM change is made. Changing a BOM carelessly can disrupt them. This piece is about changing a BOM without breaking open production.
The situation: change versus production in flight
At any moment, a manufacturer has manufacturing orders at various stages: some confirmed and planned, some in progress on the floor. Those orders were created against the BOM as it was at the time. When the BOM is then changed, a question arises: what happens to the orders that are already open? Handling that question deliberately, rather than changing the BOM and hoping, is what keeps production stable.
Understand what a BOM change does and does not touch
The first principle is to understand the relationship between a BOM and the orders made from it. A manufacturing order, once created, has its own component requirements, derived from the BOM at creation time. A later change to the BOM does not automatically and silently rewrite an order that is already in progress in a way that would be unsafe; the order has its own state. But the interaction between a BOM change and existing orders is exactly the thing to be deliberate about, because an order that has not yet started, or is partway through, can be affected differently from one that is complete. The safe approach is to know the state of the open orders before changing the BOM, not after.
Check the open orders before changing
So the first practical step is, before making a BOM change, to look at what manufacturing orders for that product are currently open and what state they are in. How many are there? Are they confirmed but not started, or in progress? This tells you what the change will be touching. Changing a BOM blind, without knowing what production is in flight, is how a change causes a surprise.
Decide how the change applies to in-flight orders
With the open orders understood, decide deliberately how the change should apply to them. Often the right answer is that the change applies to new orders from now on, while orders already in progress are allowed to complete on the basis they started on, because they are already part-built and changing them mid-flight would cause disruption. Sometimes a change is urgent enough that it must reach in-progress orders, and then each affected order has to be handled consciously. The point is that this is a decision to make, per change, not something to leave to chance.
Time the change well
A simple, powerful discipline: where possible, time a BOM change for a moment when little or no production for that product is in flight. A change made when there are no, or few, open orders for the product simply has far less to disrupt. Not every change can wait for a quiet moment, but for changes that are not urgent, choosing the timing is the easiest way to avoid breaking open orders.
Use controlled change where it matters
For a manufacturer where BOM changes are frequent or consequential, the controlled approach, managing changes through Odoo's product lifecycle management capability in Enterprise, with engineering change orders, is the proper answer. A controlled change process means a change is reviewed, including its effect on production, and applied deliberately, rather than being a direct edit whose consequences are discovered afterward.
The takeaway
Changing a BOM without breaking open manufacturing orders is a matter of deliberateness, not luck. Before changing a BOM, understand the open orders for that product and their state. Decide consciously how the change should apply to orders already in flight, often letting in-progress orders complete as they started. Time non-urgent changes for quiet moments. And for frequent or consequential changes, use the controlled change process that PLM provides. For how we approach Odoo for manufacturers, see our manufacturing work.