TIMWOODS is a mnemonic for eight common forms of waste used in Lean improvement: Transportation, Inventory, Motion, Waiting, Overproduction, Overprocessing, Defects and Skills (unused talent). These wastes consume time, cash or capacity without creating customer value.
The Eight Wastes
| Waste | Supply-chain example | Improvement question |
|---|---|---|
| Transportation | Moving pallets between temporary storage areas | Can the flow or layout eliminate a move? |
| Inventory | Excess safety stock caused by unreliable lead times | What process problem is the stock buffering? |
| Motion | Picker walking repeatedly to distant fast-moving SKUs | Can slotting or point-of-use storage reduce travel? |
| Waiting | Orders waiting for approval or trucks waiting at a dock | What dependency creates the queue? |
| Overproduction | Buying or producing earlier/more than needed | Can demand pull replace forecast-driven excess? |
| Overprocessing | Duplicate data entry or unnecessary approval layers | Does this step change the output or manage a real risk? |
| Defects | Wrong SKU, quantity, label or delivery document | Can the error be prevented at source? |
| Skills | Front-line improvement ideas never used | Are people closest to the work involved in improvement? |
Waste Is Often Connected
One problem can create several wastes. A poor warehouse layout may create excess motion, longer picking time, waiting at packing and eventually overtime. Treating only the overtime would miss the root cause.
How to Use TIMWOODS
- Observe the actual process rather than relying only on procedures.
- Map the flow and record delays, queues, rework and movement.
- Classify waste using TIMWOODS.
- Quantify the impact in time, cost, distance, inventory or defects.
- Identify the root cause before selecting a countermeasure.
- Test the change and track the KPI.
Use TIMWOODS together with value-stream mapping and process mapping.
Interview Question
Question: Give one example of inventory being waste without saying that all inventory is waste.
Answer: Inventory becomes waste when it is held beyond what the process needs for service, variability or risk. For example, excess stock created only because order quantities are unnecessarily large ties up cash and space without adding customer value.
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