Engineering changes are necessary and unavoidable. Products improve, components go obsolete, suppliers change, defects get fixed. The question isn’t whether to allow changes but whether your process absorbs them or is disrupted by them, and that difference comes down to a handful of specifics.

Where Uncontrolled Change Does Damage

Obsolete inventory. A change released without checking existing stock leaves you holding components you can no longer use. On a long-lead item bought in bulk, that’s a serious write-off.
Open orders against the old revision. Purchase orders already placed continue delivering superseded parts, sometimes for months, because nobody linked the change to open commitments.
Half-built work in progress. A change applied mid-build leaves partially completed units that match neither revision and require rework or scrap.
Documentation drift. Work instructions, inspection criteria, and test specifications that still reference the old design. The floor builds to the paperwork in front of them.

What a Change Request Should Require

Before approval, four questions need answers. What stock of the affected components exists, and what happens to it? What open purchase orders are affected, and can they be amended or must they be received? What work in progress is affected? And what is the effective date — immediate, on stock depletion, or at a specific serial or batch number?
That last one determines everything downstream. Immediate changes are appropriate for safety or quality issues and expensive otherwise. Stock-depletion changes avoid write-offs but require tracking which revision is being built. Both are legitimate; the mistake is not choosing deliberately.

Classify by Urgency

Not every change needs the same process, and applying one heavyweight workflow to all of them is why change processes get bypassed.
Safety and regulatory changes go immediately, with stock scrapped if necessary. Quality changes affecting yield or reliability go quickly with an impact assessment. Cost reduction and improvement changes should wait for stock depletion or a natural break. Administrative corrections need almost no process at all.
Three tiers is usually enough, with clear criteria and different approval requirements for each.

Give it a Rhythm

Ad hoc change releases create constant small disruption. Batching non-urgent changes into a scheduled release — monthly for most manufacturers — lets production plan around them, lets documentation be updated together, and lets procurement manage stock run-out deliberately rather than reactively.
Keep an emergency route open for the genuine cases. Just make it genuinely exceptional, and track how often it’s used. If half your changes are emergencies, the classification isn’t working.

The Measurement

Track change lead time from request to release, and track write-offs attributable to changes. If write-offs are rising, your impact assessment isn’t happening properly. If lead time is rising, the process is becoming a bottleneck and engineers will start working around it.
Workarounds are the signal to watch for. Changes implemented informally on the floor, or drawings updated without a release, mean the official process has become slower than the work requires. That’s a process design problem, not a compliance one, and treating it as compliance makes it worse.
ticktick.ai checks stock, open orders, and work in progress automatically when a BOM change is proposed, so the impact is visible before approval rather than after.