Nobody puts the overlap quantity in a presentation. It is still the number that decides whether your transfer is remembered as a project or as an incident.
A stock bridge is the inventory that carries you from the last unit the old supplier builds to the first unit the new one delivers at rate. It sounds like a logistics detail. It is really an insurance policy against everything a plan cannot predict: a late first-article approval, a component with a sixteen-week lead time, a test fixture that behaves differently on the new floor.
The size of the bridge comes from three numbers: your consumption rate, the realistic ramp curve at the new supplier, and the longest lead time in the bill of materials. Two of those are known. The third — the ramp — is where optimism lives, so we plan it from the pilot batch results rather than from the quotation.
Who owns the bridge stock matters as much as its size. If the old supplier builds it, agree the payment and storage terms in writing before the last order. If the new supplier carries it, say so in the frame agreement, because unagreed inventory is the fastest way to sour a relationship that has not even started.
The bridge also has an end date. We plan the drawdown alongside the ramp, so the last bridge units are consumed as the new line reaches rate — not left as obsolete stock two revisions later. A bridge that never gets consumed was not insurance; it was a forecasting error with a nicer name.
— GANI Contract Manufacturing engineering team