Pull Systems: Let the Customer Set the Pace

Push vs. pull in plain terms

Push builds to a forecast. Pull builds to a signal. In a push plant, the schedule says make five hundred, so five hundred get made whether anyone needs them or not, and the warehouse fills with hope. In a pull plant, nothing moves until the next step — or the customer — asks for it, and the ask is a real signal: an empty bin, a kanban card, a freed space. Push feels busy. Pull feels calm. The difference shows up in inventory, in lead time, and in how often the plant expedites work it should never have started.

Kanban without the mystique

Kanban is not a philosophy. It is a card, a bin, or a marked square that says "make one more of this, because one just got used." The number of cards in circulation is the maximum inventory allowed, which is why pull controls inventory instead of merely counting it. Start small: one part, one loop, one supplier or one internal step. Set the card count from actual usage, not from a guess, and watch what happens when a card goes missing — that missing card is a problem surfacing, which is exactly what the system is for.

Supermarkets and signals

Where true one-piece flow is impossible — a batch oven, a distant supplier — pull uses a supermarket: a small, controlled store of finished parts with a fixed maximum, replenished only when the next step takes from it. The supermarket is not a warehouse. A warehouse grows. A supermarket has a maximum, a minimum, and a signal that fires on withdrawal. Size it from real demand and real replenishment time, mark it on the floor, and treat an overfull supermarket as a defect, not a comfort. The signal is the discipline; the shelf is just where it lives.

The discipline that makes pull hold

Pull fails the same way every time: someone overrides the signal. A big order lands, a manager pushes a batch "just in case," and the cards stop meaning anything. Pull is a promise the whole plant keeps, especially under pressure — and keeping promises under pressure is a leadership routine, not a shop-floor technique. That is why pull belongs with Leader Standard Work: leaders checking the signals daily, asking why a loop broke, and fixing the cause instead of flooding the line. The method behind it is in The Lean Culture Blueprint, and the daily routine fits in your pocket: https://apps.apple.com/us/app/lean-culture-advisory/id6790203662