Key takeaways
- Lean identifies eight wastes, summarised by the acronym DOWNTIME.
- Waste is any activity that consumes resources without adding value the customer pays for.
- Several wastes (waiting, defects, excess processing) overlap directly with the six big losses and OEE.
- Seeing waste is the first step; the goal is to design it out, not just work around it.
Lean manufacturing defines waste as any activity that uses resources without adding value the customer would pay for. There are eight classic wastes, easy to remember with the acronym DOWNTIME. Learning to see them on your own floor is the first step to removing them.
The 8 wastes: DOWNTIME
Each letter is a type of waste:
- Defects (D): scrap and rework, the Quality side of OEE. Costs material, time and trust.
- Overproduction (O): making more or sooner than needed, which hides other problems and ties up cash.
- Waiting (W): idle people or machines waiting for material, instructions or the previous step. A direct availability loss.
- Non-utilised talent (N): not using the knowledge and ideas of the people who do the work.
- Transport (T): unnecessary movement of material between steps and stores.
- Inventory (I): excess raw, WIP or finished stock that hides problems and costs money to hold.
- Motion (M): unnecessary movement of people (hunting for tools, reaching, walking).
- Excess processing (E): doing more than the customer needs (over-tight tolerances, extra steps, double handling).
How the wastes overlap with OEE
Several wastes map straight onto the six big losses and OEE. Waiting is an availability loss. Defects and excess processing hit quality and performance. Overproduction often masks a slow or unreliable process. So removing waste and improving OEE are usually the same fight from two angles.
How to see and remove waste
Go and look (gemba). Walk the process, follow one part, and ask at each step whether it adds value the customer pays for. Map it, tag the wastes, and tackle the biggest first. Many wastes (waiting, motion, transport) are designed in by layout and scheduling, so the durable fix is to redesign the flow, not just to ask people to hurry.
Waiting and micro-stops are often the hardest waste to see because they are short and unlogged. Fabrico, the partner we recommend, records these stops from the machine and links them to video; the tools here are free regardless.
Where the wastes come from
The first seven wastes come from the Toyota Production System. Taiichi Ohno described them in Toyota Production System: Beyond Large-Scale Production (1988). The eighth, unused talent, was added later by Western writers; Jeffrey Liker includes it in The Toyota Way (2004).
A waste walk checklist
On a waste walk, ask one question per waste at each step of the process:
- Defects: are parts being checked, sorted or reworked here?
- Overproduction: is anything made before the next step needs it?
- Waiting: are people or machines idle, waiting for material, a decision or a repair?
- Non-utilised talent: have the operators suggested a fix that was never tried?
- Transport: how far does the part travel to reach this step, and why?
- Inventory: how much stock sits before and after this step?
- Motion: does anyone walk, reach or search to do the job?
- Excess processing: is this step doing more than the customer needs?
Which waste to start with
Start where the waste stops output. Waste at the bottleneck costs the whole line, while the same waste at a step with spare capacity costs much less. Overproduction and inventory often come next, because cutting them exposes the waiting and defects they were hiding. Size the losses with the hidden factory calculator, and use value stream mapping to see waste across the whole flow. For defects, poka-yoke (mistake-proofing) stops them at the source; for motion and searching, start with 5S.
Transport and waiting on the floor
Transport and waiting waste often sit in material handling. The guides for the AGV / AMR, electric forklift, spiral conveyor, palletizer and depalletizer cover the faults that stop material moving, so the waste can be traced to a cause. Automated storage brings its own faults, covered in the AS/RS stacker crane guide. Manual handling has its own stops too, covered in the scissor lift table and electric pallet truck guides.
Size the prize with the free OEE and downtime calculators.
FAQ
What are the 8 wastes of lean?
Defects, Overproduction, Waiting, Non-utilised talent, Transport, Inventory, Motion and Excess processing, remembered by the acronym DOWNTIME.
What is the DOWNTIME acronym?
DOWNTIME stands for Defects, Overproduction, Waiting, Non-utilised talent, Transport, Inventory, Motion, Excess processing, the eight wastes of lean.
How do the 8 wastes relate to OEE?
Several map directly onto OEE: waiting is an availability loss, defects and excess processing hit quality and performance. Removing waste and raising OEE are largely the same work.
Related: the six big losses · what is OEE · micro-stops & the hidden factory · SMED & changeover