Also called waste, seven wastes, eight wastes, TIMWOOD
What is muda?
The Japanese word for waste: anything you do that the customer would not pay for.
What else it is called
- Other names
- waste, seven wastes, eight wastes, TIMWOOD
- In French
- gaspillage
Related entries
Understanding muda
Waste, in the specific sense of activity a customer would not pay for. The seven categories are the checklist for finding it. Transport is moving material further than necessary. Inventory is anything sitting and waiting. Motion is the operator reaching, walking or searching. Waiting is the person or machine idle. Overproduction is making more or sooner than needed. Overprocessing is doing more to the part than required. Defects are parts needing rework or scrap.
Overproduction is first among equals. Build ahead of demand and you immediately create inventory to store, transport to move it, and a delay before any defect is found. Much of what looks like five separate problems on a floor is one scheduling decision showing up in five places.
The word is one of three that belong together. Mura is unevenness and muri is overburden, and in Toyota’s own framing those two are what generate most of the waste in the first place.
In practice
Walk your own floor and count only the operators actually changing the shape or condition of a part at the moment you look. In most plants it is under a third, and nobody is being lazy.
Frequently asked
What does TIMWOOD stand for?
A memory aid for the seven: transport, inventory, motion, waiting, overproduction, overprocessing and defects. Some versions add an S for unused skill, giving TIMWOODS.
Is all inventory waste?
No. Inventory held deliberately in front of a constraint, or to cover a known supply risk, is a decision. Inventory that accumulated because one station runs faster than the next is waste. The difference is whether anybody chose it.