Suppliers have good reason not to answer

When a manufacturer plans to raise volume, it needs to know which supplier will become the constraint. So it asks. Little comes back.

Process-level lead time structure is competitive information. Handing it to a customer who may reopen the price next year is a loss with nothing returned, and it may reach a rival who undercuts you. Refusal is rational, and no amount of relationship-building changes the arithmetic.

A readiness survey that asks every Tier 1 the same hundred pages does not solve this. It spreads the burden across every firm without narrowing the search, and it rarely carries past Tier 1 at all.

One number from each firm

The critical path method sums durations along a path and works in time per piece. The theory of constraints takes a minimum over production rates and works in pieces per time. The two have stayed apart for fifty years, largely because their units are reciprocal.

Normalize every process to one finished unit through the bill of materials and the batch quantity, and the dimensions match. The firm with the longest company-level lead time on the critical path is the firm with the lowest throughput capacity in the network.

That makes a provisional critical path computable from a single figure per firm: the interval between an inbound receipt and an outbound shipment. Nothing internal is disclosed. Follow-up questions then go only to the few firms that could still be the constraint, and only about the part numbers that bear on it.

Capacity, not connections

Supply chain mapping answers two questions today: who buys from whom, and where a risk flag has been raised. Neither one tells you how many units a plant can produce next month. Across the published material of the major vendors in this category, lead time, capacity and bottleneck analysis do not appear.

Supplier campaigning asks every firm the same question. This asks a narrowing subset a question specific to the product, the variant and the required production rate.

The constraint also moves. Improve it and the next one appears, which is the usual objection to any snapshot of a network. Under repeated improvement the node rank changes but the path rank largely holds, so a supplier's position does not become stale the moment one bottleneck is fixed.

Limits we hold ourselves to

The platform is filled in by firms that choose to take part. A tool that can be turned against them does not get filled in at all, so the following are structural commitments rather than preferences.

Being identified as the constraint is how a firm gets investment directed at it. Only improvement at the constraint raises what the network can deliver, which is why the lender, the manufacturer and the constrained firm all have a stake in finding it.

Where this stands

The method is published and peer-reviewed. In June 2026 the UK Government Office for Science cited it in its foresight report on supply chain risk and resilience, in the section defining upstream bottlenecks. The mechanism behind the platform is patented in Japan, with an international application pending. The platform itself is in development, and current engagements are advisory: building the network map for a manufacturer, and locating the constraint inside a single plant.