Lean Factory Simulation

A running model of an e-bike factory, built to be watched rather than read. Most lean terms are defined in a sentence and understood in a week; this is an attempt to collapse that gap by letting you see the thing happen. Nothing here is staged — the queue in front of the bottleneck forms because the station’s work genuinely sums to takt, and the line stops because an operator raised an andon.

Two altitudes, one factory

The plant view is a value stream map of the whole door-to-door flow: weld, heat treat, paint and assembly, with the stores between them. The line view takes the assembly box and walks inside it — four stations, four operators, and a water spider keeping the racks fed. A value-stream map maps processes, not workstations, which is exactly why the four stations collapse into one box upstairs.

The numbers it runs on

Takt is 60 seconds. Weld cycles at 40 seconds, heat treat at 45 in batches of eight, paint at 20 with a two-minute colour changeover, and assembly at 55 — which makes assembly the pacemaker, and the reason it is the box you step into. Down on the line, station S2 fits the bottom bracket, cranks and pedals in eight elements that sum to exactly 60 seconds, so ordinary variation pushes it over takt about half the time.

The pedal rack is deliberately too far away and the pedals arrive face down. That is planted waste, and it has consequences you can watch: walking inside the cycle, double handling, and every seventh bike failing the torque check and going down the reject chute at S2 rather than at final inspection.

Terms you can watch happen

• Takt time — the pulse at the dock — 440 minutes against 440 bikes gives a 60-second beat
• Cycle time — S2’s ring filling as the operator works through eight elements
• Lead time — the camera riding one frame from the line to the dock
• Work in process — every bike on the floor at once, most of them waiting rather than being worked
• Bottleneck — S2, whose elements sum to exactly takt
• Line balancing — a yamazumi stacked from the real steps, walking in red
• Standardized work chart — Form 3 — layout, numbered walking path, takt and cycle
• Work element — the smallest piece of work you could hand to someone else
• Kanban — an empty tote riding back to the supermarket as the reorder
• Supermarket — a store with addresses, replenished only as it is consumed
• Two-bin system — pick the front tote; when it runs dry the reserve takes its place
• Water spider — the runner on a fixed-time route who absorbs the walking
• Andon — the light that stops the line and calls a person
• Jidoka — stop rather than pass the problem downstream
• Poka-yoke — the torque check that will not release a wrongly fitted pedal
• 5S — a bench that explains itself, and drifts when nobody keeps it
• Hour-by-hour board — plan, actual, cumulative — and the why column
• Value stream map — the whole plant as boxes, stores and time

Questions

What does this simulation actually show?

An e-bike factory running at two altitudes. The plant view is a value-stream map: four processes — weld, heat treat, paint, assembly — with the stores between them and how long a frame waits in each. The line view is one of those processes close up: four assembly stations, operators working real element sequences, a water spider feeding the racks. Stepping between them is the point, because an assembly box on a map is a whole line once you walk into it.

Is the simulation using real numbers?

Yes, and they are consistent between the two views. Takt is 60 seconds — the pace demand sets. Weld runs a 40-second cycle, heat treat 45, paint 20 with a two-minute colour changeover, and assembly 55, which makes assembly the pacemaker. On the line, station S2 sums its eight work elements to exactly 60 seconds, so it breaches takt about half the time and a queue builds in front of it.

Why does a frame take half an hour to cross a plant that only works on it for three minutes?

Because of the stores between processes. Added up they hold about thirty minutes of supply against two or three minutes of actual work. Those stores are not waste you can simply delete: a heat-treat oven that cooks eight frames at a time and a paint booth that loses two minutes to every colour change both have to be covered by stock. The levers on that half hour are the batch size and the changeover, not working faster.

What is the difference between a supermarket and an inventory triangle on the map?

A supermarket is a controlled store, sized on purpose, that a downstream process pulls from — drawn open-sided, with the open side facing the supplying process. A triangle is inventory that simply accumulated. On this map the four stores are supermarkets and the only triangle is the batch sitting inside the oven, which is the honest distinction: one is a decision, the other is a consequence.

Can I use this to teach a class?

That is what it is for. It needs a desktop screen and no sign-up. The term rail on the line view doubles as a lesson order, and every term links back to a written definition if you want the reading alongside it.

More like this in the lean games and simulations catalog, or build the same chart yourself with the standardized work chart and yamazumi tools.