Plan The engineering concept for a part is converted into a detailed drawing. It provides a graphic representation of the part along with all its engineering requirements/specifications. Among other things, it defines the geometry, dimensions, tolerances, and material for the physical part. The drawing of the part acts as the plan for the manufacturer to follow when making the physical part.
Do The manufacturer uses the drawing of the part (plan) to make the physical part (do).
(Note: If you outsource the manufacturing of the part, lead times could be as much as 14 weeks or 3+ months. So, it’s a good idea to involve the manufacturer in the planning phase of the part to address any foreseeable issues as early as possible.)
Check The physical part is inspected (checked) against the drawing of the part (plan) e.g. as part of a first article inspection (FAI) or receiving inspection. Discrepancies between the physical part and its drawing are identified.
Act Decisions are made for each discrepancy to determine whether the part must comply with the existing drawing specifications or whether the drawing specifications—typically the tolerances around an attribute—should be changed.
If it’s decided that the drawing specifications are to be changed, e.g. the tolerances for one or more attributes is to be loosened, then the drawing is revised. This results in another loop through the PDCA cycle with the new drawing or plan.