Lean manufacturing is a way of running a business so that it makes what customers need, when they need it, with as little waste as possible, and keeps improving a little every day. It grew out of the Toyota Production System in Japan and has since spread to every kind of manufacturing.
Most lean guides use car-plant examples. This one is for small and medium manufacturers in India: machine shops, fabricators, press shops and job shops, where every order can be different. It covers the ideas behind lean, the eight wastes with shop-floor examples, just-in-time, the Toyota Production System, the tools to start with, and where lean efforts usually stall.
What lean manufacturing is
The word 'lean' was coined by researchers at MIT in the late 1980s and made famous by the 1990 book The Machine That Changed the World, which compared Toyota with car makers around the world. The ideas themselves are older: they come from the Toyota Production System, developed in Japan after the Second World War.
In their 1996 book Lean Thinking, James Womack and Daniel Jones summed lean up in five principles:
- Value: what the customer is actually paying for.
- Value stream: every step a product goes through, from order to delivery, and which of those steps add value.
- Flow: making the valuable steps follow each other without stopping and waiting.
- Pull: making only what the next step, and ultimately the customer, needs, instead of pushing work out in case it's needed.
- Perfection: improving continuously, in small steps, for good.
The eight wastes of lean, with shop-floor examples
Lean calls anything that takes time or money without adding value 'waste' (muda, in Japanese). Taiichi Ohno of Toyota listed seven; an eighth, unused talent, was added later. They're often remembered as TIMWOODS:
- Transport: parts moved more than they need to be, such as material carried from stores to a machine and back because the drawing wasn't ready.
- Inventory: more material, work in progress or finished stock than you need. Work in progress is the costliest, because the material and the work are already paid for.
- Motion: people walking, searching and reaching, such as the operator who goes looking for a gauge, a tool or the supervisor.
- Waiting: a job waiting for a machine, a setter, material, an inspection or a decision. In many job shops, it's the largest waste of all.
- Overproduction: making more, or sooner, than the customer needs, often to keep a machine busy. It creates most of the other wastes.
- Over-processing: doing more than the customer asked for, such as a finer finish or a tighter tolerance than the drawing needs.
- Defects: scrap and rework, including everything spent finding and fixing the problem.
- Skills: unused talent, such as the experienced operator whose ideas nobody asks for.
The waste lean guides don't list: looking for information
Walk around a busy shop floor and count how often someone stops to find something out. Which revision is the latest drawing? Has the material come? Is this job still urgent? Did the customer approve the change? Each question means a phone call, a WhatsApp search or a walk to the office.
It isn't on Toyota's list, but it shows up in several of the wastes that are: waiting while someone finds out, motion while they go and ask, and defects when they get the wrong answer, such as a job made to an old drawing. In many small and medium businesses, the information that runs the floor is scattered across WhatsApp groups, Excel sheets, inboxes and a few people's memory. Bringing it into one place is a lean improvement, even though it involves no machines at all. We've written more about this in why WhatsApp runs so much of the shop floor.
Just-in-time manufacturing
Just-in-time (JIT) means making or receiving only what's needed, when it's needed, in the amount needed. It's one of the two pillars of the Toyota Production System, and it's what 'pull' looks like in practice: a job starts when the next step is ready for it, and material arrives when the job needs it, not weeks before.
The classic tool is kanban: a card or signal, sent back from the step that uses the parts, that says 'make or send more of this'. When the card comes, you make; when it doesn't, you don't.
Full JIT with suppliers can be hard for a smaller manufacturer to start with: suppliers' lead times and minimum order quantities don't always suit small, frequent deliveries. So start inside your own floor. Don't release a job until the floor can take it, limit how many jobs are open at once, and keep the queue in front of the bottleneck short. That alone shortens your production lead time.
One warning: just-in-time without visibility is just running short. If nobody can see what's needed next and what's arriving when, cutting stock only moves the firefighting somewhere else.
The Toyota Production System
The Toyota Production System (TPS) is the way Toyota organises its production, developed by Taiichi Ohno and others from the late 1940s onwards. Lean manufacturing is, broadly, TPS described for everyone else. It's often drawn as a house:
- The roof: the goal, which is the best quality, the lowest cost and the shortest lead time.
- The first pillar, just-in-time: make only what's needed, when it's needed, in the amount needed.
- The second pillar, jidoka (automation with a human touch): stop the moment something goes wrong, so a defect is fixed at its source instead of being passed on.
- The foundation: levelled production (heijunka), standardised work and continuous improvement (kaizen).
Toyota's wider management principles, including respect for people, are described in Jeffrey Liker's book The Toyota Way. For a smaller manufacturer, the most useful lesson from TPS is jidoka's: make problems visible immediately, and fix them where they start.
Lean tools a smaller manufacturer can start with
- 5S: sort, set in order, shine, standardise, sustain. A tidy, labelled workplace where everything has a place, so nobody searches for tools.
- Visual management: a board at the bottleneck showing what's running, what's next and what's late.
- Limiting work in progress: agree a maximum number of open jobs and release a new one only when one finishes. Our WIP calculator shows what that's worth in cash and days.
- Quick changeover (SMED, single-minute exchange of die): do everything you can while the machine is still running the last job, so setups get shorter and small batches become affordable.
- Standard work: the best known way to do a job, written down simply, so results don't depend on who's on shift.
- Error-proofing (poka-yoke): fixtures and checks that make a mistake impossible, or at least obvious.
- Value stream mapping: a drawing, on paper, of every step an order goes through, with how long each step takes and how long it waits in between.
Where lean efforts stall
Lean projects in smaller companies often start well and fade within months. The usual reasons:
- The boards and charts are updated by hand, and when the person who updates them is busy, they go stale.
- Improvement depends on one champion, often the owner or an outside consultant, and fades when that person's attention moves on.
- The numbers needed to see waste, such as how long each job waited and where, aren't recorded anywhere.
- The information that would prevent the waiting is still scattered, so people keep chasing it.
None of this is a failure of the people. It's what happens when improvement depends on extra manual work.
Lean and software
Lean has a sound warning about software: don't automate waste. A messy process on a computer is still a messy process, only faster. So simplify the process first, then support it.
The right software for a lean shop follows how your work flows instead of forcing a generic process on it, and it captures information where the work already happens, so nobody has to update a screen later. That's how we work at Wisemove. We build custom systems for small and medium manufacturers around how they already work, bringing what's scattered across WhatsApp, Excel and inboxes into one place, and your team uses them through Youno, a work chat app as simple as WhatsApp. AI does the reading, sorting and drafting; a person approves anything that matters.
Quick answers
What is lean manufacturing in simple words?
Making what customers need, when they need it, with as little waste as possible, and improving a little every day.
What are the 8 wastes of lean manufacturing?
Transport, inventory, motion, waiting, overproduction, over-processing, defects and unused skills, often remembered as TIMWOODS.
What's the difference between lean and just-in-time?
Lean is the whole approach to removing waste. Just-in-time is one part of it: making and receiving only what's needed, when it's needed.
What is the Toyota Production System?
Toyota's way of organising production, built on two pillars, just-in-time and jidoka (stopping to fix problems at their source), with levelled production, standardised work and continuous improvement as its foundation. Lean manufacturing grew out of it.
Is lean only for large companies?
No. The core ideas, fewer open jobs, shorter queues, visible problems and small daily improvements, cost little and suit a 20-person machine shop as well as a car plant. The Ministry of MSME also runs a lean scheme for MSMEs (the MSME Competitive (LEAN) Scheme); check its current terms on the ministry's website.
What is 5S?
A method for organising a workplace in five steps: sort, set in order, shine, standardise and sustain. It's often the first lean tool a company tries, because the results are easy to see.
Where to start
Pick one product or one type of job. Follow a single order from enquiry to dispatch and note every step, how long it took and how long it waited. Then put your numbers into the production lead time calculator. The longest waits are your first lean project. If you find that much of that waiting is people looking for information, book a call with us.