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Toyota Production System (TPS): the house, the two pillars and how it works

Short answer

The Toyota Production System (TPS) is the way Toyota makes vehicles, built on two ideas: just-in-time, which means making only what is needed, when it is needed, in the amount needed, and jidoka, which means stopping the moment something goes wrong.

Toyota describes TPS as a system for removing waste completely, with the aim of a shorter lead time so customers get vehicles quickly, at low cost and with high quality. It is usually drawn as a house. The roof is that aim. The two pillars are just-in-time and jidoka. The foundation is heijunka (leveled production), standardized work and kaizen. The parts depend on each other, which is why a plant that copies one of them, usually kanban, rarely gets the result. Lean manufacturing is the name outside researchers gave to what they saw at Toyota.

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What is the Toyota Production System?

Toyota's own description starts with waste. The company says the system is built on removing waste completely while looking for the most efficient way to work. The stated objective is a shorter lead time, so that a customer gets a vehicle quickly, at low cost and with high quality. It also says the system rests on making work easier for the people who do it.

Toyota names two pillars. Jidoka, which it translates as automation with a human touch, means a machine or a person stops the work as soon as an abnormality appears, so a defect is never passed on. Just-in-time means each process makes only what the next process needs, in a continuous flow. Everything else in the system exists to make those two possible.

It covers how work is scheduled, how parts move, how problems surface and who fixes them. That is the difference between TPS and lean tools picked one at a time.

The TPS house, part by part

The Lean Enterprise Institute says TPS is often illustrated with a house. Toyota's own page draws none. Take away a pillar or the foundation and the roof comes down.

The TPS house

Goal

Best quality, lowest cost, shortest lead time

  • Just-in-time

    Make what is needed, when needed, in the amount needed

    • Continuous flow
    • Takt time
    • Pull system

  • Jidoka

    Stop when something is abnormal and fix the cause

    • Detect the abnormality
    • Stop the work
    • Fix the cause
  • HeijunkaSpread both the mix and the volume of work evenly across a set period
  • Standardized workThe current best way to do a job, written down
  • KaizenContinuous improvement of the standard

A house. The roof is the goal: Best quality, lowest cost, shortest lead time. Two pillars hold it up: Just-in-time and Jidoka. The foundation has three layers: Heijunka, Standardized work, Kaizen.

Read it from the ground up. The foundation makes the work steady enough for the pillars to stand, and the pillars together hold up the goal.
The parts of the TPS house
Part of the houseWhat it isWhat it means on the floorWhere to start
Roof: the goalsBest quality, lowest cost, shortest lead timeEvery change is judged against these three, togetherWhat lead time is
Pillar: just-in-timeMake what is needed, when needed, in the amount neededContinuous flow, work paced to takt time, and pull from the next processJust-in-time guide
Pillar: jidokaStop when something is abnormal and fix the causeMachines that stop themselves, operators who can stop the line, an andon that calls for helpJidoka worksheet
Foundation: heijunkaSpread both the mix and the volume of work evenly across a set periodA repeating mix of models through the day, not one long batch of eachHeijunka box planner
Foundation: standardized workThe current best way to do a job, written downTakt time, a work sequence and a set amount of in-process stock for each jobStandard work sheet
Foundation: kaizenContinuous improvement of the standardSmall changes by the people doing the work, checked and then made the new standardKaizen guide

The pillars are Toyota's. The roof and foundation wording is the common drawing, not Toyota's text or the Institute's, and drawings vary.

The TPS house template puts the house on one page to check your own plant.

What are the two pillars of the Toyota Production System?

The two pillars are just-in-time and jidoka. Just-in-time means making only what is needed, when it is needed, in the amount needed. Jidoka, which Toyota translates as automation with a human touch, means stopping as soon as something abnormal appears so a defect is never passed on.

Just-in-time

Toyota points out that a car has more than 30,000 parts, so making each one early and storing it is not an option. Its page gives three principles: make only what the customer needs, do not let goods or information be held up, and make things at the pace they are sold. The next process takes what it needs and the first replaces only what was taken. A kanban card carries that message.

Jidoka

Jidoka is the older idea. Toyota traces it to Sakichi Toyoda's power loom, which stopped when a thread broke. On a line today it means equipment that stops itself, and an operator who can stop the work by pulling a cord. The andon board shows where. A machine that stops itself does not need watching, so one operator can look after several. Toyota adds a rule that is easy to miss: do the work by hand first, improve it, and only then build what you learned into the machine.

The pillars need each other. Just-in-time takes out the stock that hides problems, so every defect now stops the flow. Jidoka is what makes that bearable, because it catches the defect where it was made and forces a fix.

The foundation: heijunka, standardized work and kaizen

Heijunka is leveling. Customers do not order evenly, and if the plant follows every swing, each process upstream needs spare people, machines and stock for the peak. So the plant takes the demand for a period and spreads both the quantity and the mix evenly across it. The Lean Enterprise Institute defines heijunka as leveling the type and quantity of production over a fixed period. A pull system fed an uneven schedule passes the swings up the line, which is why drawings of the house put it at the base.

Standardized work has three elements in the Institute's definition: takt time, the sequence in which the operator does the work, and the standard in-process stock needed to keep the job moving. It is recorded on forms such as the standardized work combination table.

Kaizen keeps the house moving. A problem found by jidoka, or a gap against takt, becomes a small change that is checked and written into the standard.

A worked example: leveling one week of production

Illustrative numbers. A cell assembles three pump models. This week's orders are 600 of model A, 300 of B and 100 of C, which is 1,000 pumps. The cell runs five days with 450 minutes of working time a day.

The same week, batched and leveled
ModelOrders this weekBatched: when it is builtLeveled: built every dayLeveled: share of each 10 pumps
A600Monday to Wednesday1206
B300Thursday and Friday morning603
C100Friday afternoon201
Total1,0005 days20010

Takt time is 450 minutes ÷ 200 pumps = 2.25 minutes, or 135 seconds a pump. One repeat of 10 pumps takes 22.5 minutes and the cell runs 20 repeats a day.

One week of pumps: batched and leveled

Example numbers

Batched: one model at a time

  • Mon
    • A
    • A
  • Tue
    • A
    • A
  • Wed
    • A
    • A
  • Thu
    • B
    • B
  • Fri
    • B
    • C

Leveled: the same 10 pumps, 20 times a day

  • A
  • B
  • A
  • A
  • B
  • A
  • C
  • A
  • B
  • A

10 pumps at 135 seconds each is 22.5 minutes. 20 repeats fill the 450 minute day.

Batched: model A fills Monday to Wednesday, model B Thursday and Friday morning, model C Friday afternoon. Leveled: the pattern A B A A B A C A B A repeats 20 times a day, every day.

Both rows build 600 of A, 300 of B and 100 of C. Batched, model C is built once, on Friday afternoon. Leveled, it comes round every 22.5 minutes, all week.
  • Batched, the cell builds 200 pumps a day either way, but a customer who orders model C on Monday waits until Friday afternoon.
  • Batched, the process that supplies model A housings is flat out for three days and idle for two. It needs stock or spare capacity to cope.
  • Leveled, the cell repeats a pattern of 10 pumps, such as A B A A B A C A B A, so every model is built every 22.5 minutes.
  • Leveled, each supplier sees the same small demand all day: 120 A housings, 60 B and 20 C, every day.

The catch is changeovers. The leveled pattern switches model 8 times in every 10 pumps, so it only works once a changeover takes seconds. Quick changeover work usually comes first. Work out your own takt with the takt time calculator.

The seven wastes TPS sets out to remove

Ohno's seven forms of muda, as listed from his 1988 English edition, are the target of the whole house.

  • Overproduction: making more or sooner than the next step needs.
  • Waiting: people or parts idle.
  • Transport: moving parts further than the work needs.
  • Over-processing: effort the customer does not value.
  • Inventory: stock that hides problems.
  • Motion: walking and reaching that adds nothing.
  • Defects: making it wrong and fixing it.

Which part of the house is missing?

Which part of the house is missing

  • What you see

    Big batches, long waits for each model

    Part of the house

    Heijunka

    Level the mix across the day

  • What you see

    Defects pass to the next station

    Part of the house

    Jidoka

    Agree what is abnormal and let operators stop

  • What you see

    Every shift does the job differently

    Part of the house

    Standardized work

    Write the current best way with the operators

  • What you see

    The same problem keeps coming back

    Part of the house

    Kaizen

    Fix one cause a week and rewrite the standard

Read the left card as what you see on the line. The yellow card is the part of the house that is weak and the first move.

Where TPS came from

TPS was not designed in one go. Toyota's account starts in a loom works.

How the Toyota Production System came together

  1. 1896Sakichi Toyoda's power loom stops itself when a thread breaksThe origin of jidoka
  2. 1924The Type-G automatic loom changes shuttles without stoppingToyota calls it the first automatic loom with a non-stop shuttle change
  3. 1938Kiichiro Toyoda brings conveyor flow production to the body line at the Koromo plantFlow reaches car making. Kiichiro is credited with the just-in-time idea in the 1930s
  4. 1949 to 1950Taiichi Ohno takes his first steps toward just-in-time in the machine shop he managesPull and flow tried in practice
  5. 1978Ohno publishes Toyota Production System in Japanese. The English edition follows in 1988The system described by the person who led it
  6. 1984Toyota and General Motors open the NUMMI joint venture in CaliforniaTPS begins to spread outside Japan in earnest
Loom and Koromo dates are Toyota's. Ohno's own dating of 1949 to 1950 and the NUMMI date are as given by the Lean Enterprise Institute.

Ohno's book is the shortest way to hear the reasoning from its source.

TPS, lean manufacturing and the Toyota Way: the difference

Three names that get used as one
NameWhose wordsWhat it describes
Toyota Production SystemToyota, with Ohno's 1978 book the classic accountHow Toyota makes vehicles: the house on this page
Lean manufacturingMIT-led researchers, in The Machine That Changed the World in 1990The same practices described for any company, later reduced to five principles
The Toyota WayToyota in 2001, and Jeffrey Liker's book in 2004The company's values and management habits: continuous improvement and respect for people

So lean is TPS seen from outside. The lean principles talk about value streams and say little about jidoka or leveling, which Toyota treats as structural. A stuck lean program often lacks one of those two.

How to start with TPS in one area

  1. 1

    Choose one line and its goal

    Pick a line with steady demand and write down today's lead time, defect rate and cost per unit. These are your roof.

  2. 2

    Make the work stable and standard

    Record the current best method for each job with the operators. Fix the equipment that breaks most often.

  3. 3

    Calculate takt and level the schedule

    Divide working time by demand, as in the example, and plan a repeating mix by day.

  4. 4

    Build in the stop

    Decide what counts as abnormal at each station, give operators a way to signal it, and agree who responds and how fast.

  5. 5

    Connect the steps with flow and pull

    Move steps together where you can. Where you cannot, add a small store and a kanban loop.

  6. 6

    Improve the standard

    Take the most frequent stop each week, find its cause and rewrite the standard. Then repeat.

The order follows the house from the ground up. Plants that begin at step 5, because kanban is the visible part, find the cards expose problems they have no routine for solving.

Common mistakes when copying TPS

  • Copying tools without the house. Kanban without leveling, or andon with nobody responding, gets abandoned.
  • Treating jidoka as automation. The point is that work stops and the cause is fixed.
  • Cutting stock first. Stock falls as a result of flow, quick changeovers and reliable machines.
  • Skipping standardized work. Kaizen with no standard is a string of changes nobody can hold.

Go deeper

This page is the short version. These guides cover each part in full.

All our articles on this subject are in the lean manufacturing fundamentals topic.

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FAQ

Questions about toyota Production System

  1. Toyota's own Toyota Way, written in 2001, rests on continuous improvement and respect for people. In Jeffrey Liker's account, leaders should understand the work thoroughly, live the philosophy and teach it, and go and see the situation themselves instead of relying on reports.

  2. Just-in-time and jidoka. Just-in-time means making only what is needed, when it is needed, in the amount needed. Jidoka, which Toyota translates as automation with a human touch, means stopping as soon as an abnormality is detected so defects are not passed on.

  3. No single person. Toyota credits Sakichi Toyoda with the idea behind jidoka and Kiichiro Toyoda with just-in-time. Taiichi Ohno, backed by Eiji Toyoda, built the working system on the shop floor from the late 1940s and later described it in his book Toyota Production System.

  4. TPS is Toyota's own system. Lean manufacturing is the name researchers gave it in 1990 when they described it for other companies, and it was later summed up in five principles. Lean is broader and looser. TPS is more specific, with jidoka and leveled production built into its structure.

  5. A drawing of the system as a building. The roof is the goal of best quality, lowest cost and shortest lead time. The two pillars are just-in-time and jidoka. The foundation is heijunka, standardized work and kaizen. It shows that the parts hold each other up.

  6. Yes. Toyota still builds vehicles, and the Toyota Production System is how it runs the work. Its own page describes a vehicle as more than 30,000 parts, which is why it makes each part only when the next process needs it.

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