What is waste in lean?
In lean thinking, waste (muda) is any activity that consumes time, money or effort without adding value for the customer. Most processes are far more waste than value: in a typical value stream, less than 5% of the lead time adds value. Learning to see waste is the first lean skill; the 8 wastes give you categories to look for, and costing them helps decide what to fix first.
The 8 wastes (TIMWOODS)
| Waste | What it looks like | Typical countermeasure |
|---|---|---|
| Transport | Moving material or information between places | Flow layout, point-of-use storage |
| Inventory | Stock and WIP above what is needed now | Kanban, smaller batches, levelling |
| Motion | Walking, reaching, searching, bending | 5S, ergonomics, spaghetti diagram |
| Waiting | People or machines idle | Line balancing, SMED |
| Overproduction | Making more or earlier than needed | Pull, takt time |
| Overprocessing | Extra steps, checks or quality nobody asked for | Value analysis, standard work |
| Defects | Scrap, rework, errors, complaints | Poka-yoke, root cause analysis |
| Skills | Ideas and talent not used | Kaizen, involvement, training |
Waste analysis example
A waste walk in an order fulfilment area records eight observations, one per waste. Re-picking mis-picks (9 a day, 15 minutes each) and double-handling pallets (30 moves a day, 4 minutes each) each cost about 500 hours a year. Packers wait for order waves, walk to the office for labels and re-check cartons that the scale has already checked. Gift sets built before orders end up re-worked, and 14 pallets clog the dock. Costed at $32 an hour plus direct costs, the area loses about $83,000 a year, with defects the most expensive waste. Unused skills cost nothing on the chart, but the packers' ideas solve several of the others.
From waste to improvement
- Pick the most costly waste, or the one that causes others (often overproduction or waiting).
- Find its root cause with 5 Whys; waste is usually a symptom.
- Run a quick kaizen or, for bigger problems, a kaizen event.
- Measure again on the next waste walk and share the savings.
How to use this Waste Analysis tool
- Describe the area. Enter the area or process, the labour rate and the number of working days per year.
- Walk the process. For each waste you see, add an observation and choose its type from the 8 wastes.
- Quantify it. Enter how many times a day it happens, minutes lost each time and people involved, plus any other yearly cost.
- Read the chart. The chart ranks the 8 wastes by yearly cost, so you know where to start.
- Record ideas. Note an improvement idea for each waste, ideally from the people who do the work.
- Export. Export the waste analysis to PDF or Excel for the improvement plan.
Frequently asked questions
What are the 8 wastes of lean?
Transport, Inventory, Motion, Waiting, Overproduction, Overprocessing, Defects and Skills (unused talent), often remembered as TIMWOODS or DOWNTIME. The first seven come from the Toyota Production System (Taiichi Ohno); the eighth, unused skills, was added later.
What does TIMWOODS stand for?
T: Transport, I: Inventory, M: Motion, W: Waiting, O: Overproduction, O: Overprocessing, D: Defects, S: Skills. DOWNTIME is the same list in another order: Defects, Overproduction, Waiting, Non-utilized talent, Transport, Inventory, Motion, Extra processing.
Which waste is the worst?
Overproduction is often called the worst, because it causes most of the others: making too much, too early, creates inventory, transport, storage, handling and hides defects. In practice, the most expensive waste in a given area is the one to tackle first, which is why this tool costs each one.
How do you measure waste?
Observe and count: how often does it happen per day, how many minutes does it take, how many people are involved? Multiply by working days to get hours a year, and value them at the labour rate. Add direct costs such as scrap, rework material or inventory holding cost.
What is a waste walk?
A waste walk is a short, focused visit to the process to spot and record the 8 wastes, ideally with the people who do the work. Use the eight categories as a checklist, record each example with where it happens and how often, and estimate its cost.
What is the difference between value-added and non-value-added work?
Value-added work changes the product or service in a way the customer is willing to pay for. Non-value-added work is waste and should be removed. Some non-value-added work is required (by regulation, or with today's technology) and should be minimized.