Lean manufacturing is a way of running production that removes waste, so good products flow to the customer at the rate the customer needs them. It applies lean thinking to making physical products, from a single cell to a whole plant.
This guide covers the principles of lean manufacturing, the main tools and how they fit together, lean management on the shop floor, the numbers to track and how to implement it. For the wider ideas, start with the lean methodology guide.
Key takeaways
- Lean manufacturing comes from the Toyota Production System, built on just-in-time and jidoka.
- The tools work as a system: stable workplaces, standard work, flow at takt time and quick response to problems.
- A management system of tiered huddles, leader standard work and gemba walks keeps the gains in place.
- OEE, takt time and lead time are the numbers most plants track first.
- Start with one model line, paper and visual boards, then add software where manual tracking slows you down.
What is lean manufacturing?
Lean manufacturing is a production approach that removes waste so products flow to the customer at the rate the customer needs them.
It grew from the Toyota Production System. Toyota describes that system as resting on two pillars. Just-in-time means making only what is needed, when it is needed. Jidoka means stopping to fix problems as soon as they appear.
John Krafcik used the term lean production in a 1988 Sloan Management Review article. It spread through the 1990 book The Machine That Changed the World.
Lean manufacturing principles
Lean manufacturing follows the five lean principles that James Womack and Daniel Jones set out in Lean Thinking. On a production floor, each one has a concrete meaning.
Value: start from what the customer is paying for, such as a part that fits, arrives on time and works. Machining, assembly and testing that serve this add value. Moving, storing and recounting parts do not.
Value stream: follow one product family from raw material to shipping dock, and draw every step with a value stream map. Most of the lead time usually sits in queues between steps, not in the steps themselves.
Flow: arrange machines and people so parts move from one step to the next with little waiting. Cells, one-piece flow and quick changeovers make this possible.
Pull: build to replace what the next process or customer has used, signaled by kanban, rather than to a forecast pushed onto the floor.
Perfection: improve in small, repeated steps through kaizen. Each improvement exposes the next problem to work on.
Two more ideas from Toyota run through all five: build quality in at each step, and respect the people who do the work by involving them in improving it.
The foundation: a stable workplace
Lean tools depend on stable, predictable work. Without that, flow and pull break down quickly.
5S gives every item a place and makes anything out of place obvious. The guide to a 5S program that lasts covers how to keep it going. Plants often run 5S audits with 5S audit software.
Standard work sets the current agreed way to do each job, with the sequence, timing and stock needed. It becomes the baseline for every later improvement. Work instructions software puts it at the workstation.
TPM, or total productive maintenance, keeps machines available by sharing routine care between operators and maintenance. A CMMS tracks the planned and breakdown work.
Making products flow
Takt time sets the pace. It is the available working time divided by customer demand. The takt time calculator works it out and shows how many operators the work content needs.
Kanban cards or bins signal when to make or move more, so stock is replaced only as it is used. E-kanban software does the same with scans and digital signals.
Heijunka levels the mix and volume of production across the day. That smooths the load on people, machines and suppliers.
SMED cuts changeover time, so smaller batches become practical. Smaller batches mean less inventory and shorter lead times. Time study software helps measure the steps.
Building quality in
Lean manufacturing aims to stop defects at the source, rather than finding them at final inspection.
Poka-yoke devices make mistakes hard or impossible, such as a fixture that only accepts a part the right way around.
Andon lets anyone signal a problem and get help fast. Andon software routes the call and records how long the response took.
Jidoka stops a machine or line at the first abnormality, so one defect does not become hundreds.
The numbers to track
OEE
OEE, or overall equipment effectiveness, multiplies availability, performance and quality into one figure. The losses behind it matter more than the figure itself. Use the OEE calculator and see the OEE method page.
Takt, cycle and lead time
Takt time against cycle time shows whether a line can meet demand. Lead time shows how long an order waits from start to finish.
Little's Law
Little's Law links work in progress, throughput and lead time. Cutting work in progress shortens lead time if throughput holds. Try the Little's Law calculator.
Quality and delivery
First-time-through quality and on-time delivery round out most plant scorecards.
Solving problems on the floor
Lean plants treat problems as information. The goal is to find the root cause and stop it coming back.
Simple problems often need only five whys. Problems with several possible causes suit a fishbone diagram.
Larger problems go through A3 problem solving, which fits the whole story on one sheet. The A3 step-by-step guide walks through each box.
Root cause analysis software and CAPA software help when you must track actions across sites or prove them in an audit.
Lean management in manufacturing
Tools change the process. Lean management in manufacturing is the routine that keeps those changes in place and finds the next problem. Without it, 5S areas drift and standard work stops matching what people actually do.
Tiered huddles. Each shift starts with a short meeting at the team board, covering safety, quality, delivery and cost. Problems the team cannot solve go to an area huddle, then a site huddle, often within the same morning. Daily management software runs these boards across shifts and sites.
Leader standard work. Team leaders, supervisors and managers each follow a written routine: check the board, walk the area, respond to andon calls and follow up on open actions. The leader standard work entry explains the idea.
Gemba walks. Managers go to the line to see problems first hand and ask questions, rather than wait for a report. The gemba walk page explains how to run one that helps the team.
Strategy deployment. Hoshin kanri links the plant's few yearly goals to the measures on each team board. The lean management guide covers these routines in more depth.
Lean operations beyond the line
Lean operations takes the same thinking beyond the production line, to every process that supports it. Waste in planning, purchasing or maintenance slows the floor just as much as waste at a workstation.
Order handling and planning: map the information flow as well as the material flow. Long approval chains and batch planning runs often add more lead time than the factory itself.
Materials and suppliers: extend pull to the warehouse and to suppliers with kanban loops and supermarkets, so stock is held where it is used. E-kanban software carries the signals between sites.
Maintenance and support: plan maintenance around takt and changeovers, and treat repeat breakdowns as problems to solve with TPM, not as routine work.
Benefits of lean manufacturing
The benefits of lean manufacturing come from removing waste rather than working harder. The size of each gain depends on the starting point and on how well the management system holds.
Shorter lead times. Smaller batches and less waiting mean orders move through the plant faster, so the plant can respond to changes in demand.
Less inventory and floor space. Pull and smaller batches cut the stock held between steps, which frees cash and space.
Fewer defects. Poka-yoke, jidoka and standard work catch problems at the source, so less scrap and rework reach later steps or the customer.
More reliable delivery. Stable equipment and leveled production make output more predictable.
Safer, more engaged teams. Organized workplaces are safer, and people who solve problems every day have more say in how their work is done.
Lean manufacturing examples
A changeover team films a die change, separates internal from external steps, and moves preparation outside the stop. That is SMED in practice.
A cell replaces a parts store with a two-bin system, so the line refills from a small supermarket. That is kanban and pull.
An operator presses an andon button when a part will not fit. A team lead arrives, the cause is found, and a fixture change stops it returning. That is jidoka and poka-yoke together.
The lean manufacturing examples guide covers more cases, including ones outside manufacturing.
Where software helps
Paper boards and spreadsheets are a good place to start. They keep the focus on the method, not the tool.
Software earns its place when manual tracking becomes slow or unreliable. Common examples are machine downtime data, many kanban loops, or audits across several sites.
The lean manufacturing software hub groups the categories: OEE software, andon software, CMMS, e-kanban, work instructions and more. Each has a buying guide and a shortlist.
How to implement lean manufacturing
Lean manufacturing implementation usually goes as a series of small, checked steps in one area, then spread to the next. A typical sequence looks like this.
Step 1. Choose a model line or cell, ideally the constraint. Improving a step that is not the bottleneck will not raise output.
Step 2. Walk the process and draw a current-state value stream map. Measure OEE and lead time by hand for a few weeks. The getting started with OEE guide explains how.
Step 3. Stabilize the area with 5S, standard work and basic TPM, so the process repeats the same way each time.
Step 4. Attack the largest loss with a focused improvement, such as SMED for long changeovers or poka-yoke for a repeat defect. Use PDCA to test each change.
Step 5. Set the pace with takt time and connect steps with flow and kanban pull.
Step 6. Put the management system in place: a team board, a daily huddle, leader standard work and regular gemba walks. Hold the gain, then move to the next area.