Lean manufacturing: problems, tools and a DMAIC example

Lean was born on the factory floor, and that is still where its tools are easiest to see at work. This page gathers the problems plants usually tackle, the tools that suit them and how a project runs from start to finish.

In short

Lean manufacturing is a way of running production that removes waste, meaning any step, wait or movement the customer does not pay for, so that products flow through the plant with fewer delays, defects and stock. DMAIC gives each improvement a structure: define, measure, analyse, improve and control.

Typical improvement problems

Long changeovers

Format or product changes take a large share of the shift, so the line runs in big batches and stock builds up between steps.

Scrap and rework

Defects found late in the process consume material and capacity, and the cause is often far upstream from where the defect appears.

Unplanned stoppages

Breakdowns, missing material and waiting for a decision interrupt the flow and make output hard to predict.

Work in progress between steps

Pallets waiting between operations hide problems, take up space and lengthen the time from order to delivery.

Tools that fit

Project CharterPins down which line, which product family and which result the project is after, so the team does not try to fix the whole plant at once. In LeanOS the charter, the KPIs and the actions stay linked in each project.Value stream mapShows the flow from raw material to dispatch, with the waits and the stock between steps, which is where most of the lead time hides.8 wastesGives the team a shared vocabulary to spot overproduction, waiting, transport, over-processing, inventory, motion and defects on the floor.Ishikawa diagramOrganises the possible causes of a defect or stoppage by machine, method, material, manpower, measurement and environment.Control planSets what is checked, how often and by whom once the improvement is in place, so the line does not drift back.

A typical DMAIC project

Reducing changeover time on a packaging line

1Define: the team writes the charter. The problem is the time the line stands still between two formats; the scope is one line and its most frequent changeovers; the goal is set against the current baseline.
2Measure: several changeovers are filmed and timed step by step, from the last good unit of one format to the first good unit of the next. The team separates the tasks done with the line stopped from those that could be done while it runs.
3Analyze: an Ishikawa diagram and the 5 whys show where the time goes: tools fetched from another area, adjustments by trial and error, settings not written down.
4Improve: tasks are moved outside the stoppage, a changeover cart is prepared, settings are recorded and a standard sequence is tested on several shifts before it is adopted.
5Control: the control plan sets who records each changeover time and how often it is reviewed, and the standard is part of the training for new operators.

Common KPIs

OEEChangeover timeFirst pass yieldScrap rateManufacturing lead time

Frequently asked questions

What is the difference between Lean manufacturing and Six Sigma?

Lean focuses on flow and waste, Six Sigma on variation and defects. Most improvement programmes combine them and use DMAIC as the common structure.

Where should a plant start with Lean?

With one concrete problem on one line, a clear charter and a value stream map of that flow. A first project that closes well teaches more than a plant-wide launch.

Can I run a manufacturing project in LeanOS?

Yes. LeanOS is a web app for DMAIC projects with the value stream map, KPIs and action plan linked, and the free plan covers one project.

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