Definition
A production stage is one observable phase of work between input (parts arrive) and output (parts ready for the next stage). Each stage has exactly one owner who decides closure, an explicit start trigger (e.g. parts on bench), and an explicit end trigger (e.g. QC signed). Stages may run in parallel where the trade allows.
Example
Worked exampleA joinery shop's assembly stage starts when cut parts arrive at the assembly bench. It ends when the carcass is complete, mid-stage QC has passed, and the unit is moved to the finishing bay. The stage owner is the assembly lead.
Why it matters
Without explicit stages, the production process happens but is opaque to the office. Stages create the observability needed for capacity planning, risk-to-install calculation, and quoted-vs-actual labour tracking.