Engineering change order

An ECO (engineering change order) is the document that formalizes a change to released drawings, models or bills of materials. Without it, every department holds a different version of the truth: engineering changed the 3D, the shop still uses the old PDF and purchasing bought the item that was dropped from the design.

How it works

A typical change flow has a request (the problem or improvement), impact analysis (parts, stock, tooling and customers affected), approval, execution (new drawing and BOM revisions) and communication (a change notice, or ECN, to whoever needs to know). Each changed drawing moves up a revision, and the ECO states what to do with parts in stock and in process: use, rework or scrap.

Practical example

A customer asks to change an M6 hole to M8 on a bracket. The ECO lists the three affected drawings, the BOM that changes the screw, the 120 parts in stock (can be reworked) and sets revision C from the next batch on. Shop, purchasing and quality get the notice the same day.

Common mistakes

• Changing the 3D and forgetting to bump the PDF revision.
• Not telling purchasing and finding obsolete stock months later.
• Making the change over chat with no record of who approved it.