Manufacturing
Why an Engineering Change Costs More After Launch
Modifying a product once production has started requires reworking tooling, documentation, inventory and approvals simultaneously, which is why the same change costs a fraction as much during design.
A design change that would take an afternoon during development can take months and a great deal of money once production has started. The reason is how much has been committed in between.
Commitment accumulates before the first unit
Bringing a product to production commits tooling, supplier contracts, test fixtures, packaging, documentation and regulatory submissions, each built around the design as it stood.
A change after that point does not alter a drawing; it alters every one of those committed items that depends on the affected feature.
The cost of the change is therefore the cost of updating the whole committed set, not the engineering effort of the modification itself.
Tooling is the largest single item
Moulds, dies and fixtures are cut in hardened material to precise dimensions, and many changes cannot be made to an existing tool at all.
Where modification is possible, it typically means adding material back and recutting, which takes weeks and carries a risk that the tool will not perform as before.
Where it is not, a new tool must be made from scratch, with the lead time and cost of the original.
Inventory already exists in several places
By the time a change is proposed, parts to the old design sit in the supplier's stock, in transit, in the plant, and in finished goods and service inventory.
Someone must decide the cut-in point and what happens to the existing material: use it up, rework it, or scrap it.
Managing that transition across several locations simultaneously is a substantial coordination task, and errors produce mixed builds that are difficult to trace later.
Approvals may have to be repeated
Where a product is certified, tested or approved by a customer or regulator, a change can require part of that process to be redone before shipping resumes.
Whether it does depends on what changed and how the approval was scoped, which is why firms structure submissions to limit what a minor change reopens.
The timeline for reapproval is generally outside the firm's control, so it becomes the determining factor in when the change can take effect.
Why changes still happen
Despite the cost, changes are made continuously for good reasons: field failures, component obsolescence, cost reduction, regulatory updates and supplier changes.
Firms manage this through formal change control, where proposals are assessed for cost, risk and timing before approval, and grouped where possible so one disruption covers several changes.
The general principle is that changes are cheapest early, which is the practical argument for resolving design questions before production commitments are made rather than after.
Questions readers ask
Does this mean bilateral trade deficits are meaningless?
They measure gross flows accurately. They are a poor proxy for where value was created, which is why value-added measures were developed alongside them.
Is assembly work worth attracting?
It brings employment and can be a route to upstream capability, which several economies have followed. Whether it stays an entry point or becomes an endpoint depends on what is built around it.
