The 7 wastes of Lean (muda): TIM WOOD explained
Transport, inventory, motion, waiting, over-processing, overproduction and defects. You remember them with one question: who is TIM WOOD?
The 7 wastes of Lean Manufacturing — the muda — are the seven ways your factory eats time, money and effort without adding a thing to the product.
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Spotting them is the work that comes before any improvement. You can't remove what you can't see.
They're remembered with a rule that works surprisingly well on the floor: ask yourself who is TIM WOOD?
| Initial | English | How it shows up |
|---|---|---|
| T | Transportation | moving material without transforming it |
| I | Inventory | stock that waits and hides problems |
| M | Motion | the operator walking or searching |
| W | Waiting | piece or person standing still |
| O | Over-processing | more quality than the customer pays for |
| O | Over-production | making early or making too much |
| D | Defects | rework, scrap, complaint |
One by one
Transport — every move adds cost and a risk of damage, and adds no value at all. It's nearly always a symptom of a plant layout you inherited rather than designed.
Inventory — stock looks like security. It's a cushion that covers up your problems: the breakdown, the slow changeover, the supplier who lets you down. Bringing it down hurts because it drags them all out at once. Which is exactly what it's for.
Motion — the operator's, not the material's. Looking for the tool, turning round, bending down, walking to the store. This is where 5S gives you minutes back on every shift.
Waiting — the piece waiting for a machine. Or the operator waiting for material, a decision, a signature. It's usually your biggest waste and it's the one nobody writes down anywhere.
Over-processing — giving the product more than the customer values. A finish nobody sees, a report nobody reads, a tolerance tighter than the drawing asks for.
Over-production — for Ohno, the worst of the seven. Because it generates all the others: making early forces you to transport, to store, and if something goes wrong, to rework an entire batch.
Defects — the most visible and the most expensive. And the price rises the later you catch it: in the line it's an adjustment, at the customer it's a complaint.
The bridge to 2026
Of the seven, three can now be measured on their own and without stopping. That's where I see the clearest return, by a distance.
Waiting and defects are the first to move when the line watches itself. The stoppage is logged with its reason at the moment it happens, not when somebody remembers. And the defect gets caught on the piece going past, not at final inspection with the batch already made.
At a bakery we work with, the system even warns that two pieces are too close together and are going to stick in the oven. In other words: it warns you about a defect that doesn't exist yet. Ten years ago you couldn't have told anyone that.
Then there's inventory, the most interesting of the three. You stop needing the cushion when the process is reliable and you can see it. Because nobody piles up stock for fun — they pile it up out of mistrust. When you know what's happening on your line right now, that mistrust drops. And the stock drops behind it, on its own.