Engineering change order: effectivity and what happens to existing stock

An engineering change order is the document that authorises a change to a released product definition — a drawing, a specification, a bill of materials — and records what was decided. It typically follows a change request, which proposes the change, and is followed by a change notice, which tells everyone affected that it has happened.

What distinguishes a working change process from a nominal one is not the approval routing. It is whether the order answers the two questions that determine what actually happens on the floor: from when does this apply, and what do we do with the parts, sub-assemblies and finished goods that already exist under the old definition.

What an engineering change order must state

• The change, precisely, with the affected documents listed at their current and new revisions.
• The reason — cost, quality, obsolescence, customer request, safety — because the reason drives the urgency and the disposition.
• Effectivity: a date, a serial number, a lot, or on exhaustion of existing stock. Vague effectivity is the commonest defect.
• Disposition of existing material at each stage: raw stock, work in progress, finished goods, field units, and spares.
• Whether the change is backwards compatible, and what happens to units already with customers.
• Cost and lead-time impact, and who bears it where a supplier is involved.
• Approvals, by role rather than by name, and the date each was given.

Disposition is where money is lost

Use up existing stock, rework it, scrap it, or return it to the supplier — each is a legitimate answer and each has a different cost, and the decision belongs in the order rather than to whoever is standing in the stores when the question arises. A change approved without disposition instructions produces a warehouse holding parts nobody will confirm as usable, which quietly becomes a write-off at the next stocktake.

Safety and regulatory changes are not effectivity decisions. Where a change corrects a hazard or a compliance defect, "use up existing stock" is usually not available, and the disposition extends to units already sold. Treat that class of change as a different process with a different approval path.

Keep the request separate from the order

A change request is a proposal that may be rejected; a change order is a decision. Merging them produces a queue in which everything is approved because rejecting feels like reversing something already agreed. Keeping the two distinct also produces a useful record: the requests that were declined, and why, which is the institutional memory that stops the same change being proposed annually.

Keeping the paper trail

What matters later is being able to reconstruct which definition a given unit was built to. Ettex Docs holds the change orders with version history and the approvals, Ettex Records keeps them against the affected part numbers with their effectivity, and the structure being changed is covered in bill of materials, kept current as described in bom management.

To be clear: this is documents and records, not PLM or quality management software. In regulated manufacturing the change process is part of the quality system and is audited as such; what this covers is the content of the decision, which no system supplies for you.