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Practical guide · Kaizen and continuous improvement

Continuous improvement in manufacturing: how the practice works day to day

Short answer

Continuous improvement is the habit of making work a little better, over and over, by the people who do the work. In a plant that means operators and team leaders spotting problems in their own area, trying a small change, checking whether it helped and then making the better way the standard. This guide covers the loop behind it, the three sizes of improvement work, a daily routine, a worked example and the tools that fit each kind of problem.

Continuous improvement in manufacturing is the ongoing practice of finding small problems in daily work, testing a change with the plan, do, check, act loop, and writing the better method into the standard so the gain holds. It is done every day by frontline teams, with larger kaizen events and projects for problems a team cannot fix alone.

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A short story from the plant floor

· 0:48

What's a Kaizen? Explained like I'm five

A 60-second explainer of kaizen. Putting one toy away each day beats one giant Saturday cleanup, and everyone tidies their own corner.

Press play to load the player from YouTube, or watch it on YouTube.

Transcript

Taken from the script the voices read.

  1. 0:00Gurpreet. Explain a Kaizen like I'm five.
  2. 0:04Kaizen is continuous, incremental, employee driven improvement.
  3. 0:08No. Simpler.
  4. 0:10Okay. Picture your messy bedroom.
  5. 0:13I'd clean it all on Saturday!
  6. 0:15That's one big project. By Wednesday, it's messy again.
  7. 0:19Instead, put just one toy away today.
  8. 0:22One toy? That's nothing!
  9. 0:23Small is the point. It's easy, so you keep doing it.
  10. 0:26Tomorrow, one more. Then one more.
  11. 0:29Do I tidy Mom's stuff too?
  12. 0:31No. Everyone fixes their own corner.
  13. 0:34And you've been doing it your whole life.
  14. 0:36Like learning to ride my bike!
  15. 0:38Exactly. Tiny fixes, every day.
  16. 0:41Kaizen is lots of tiny fixes, by everyone, every day.
  17. 0:45Correct. Now go put one toy away.

What is meant by continuous improvement?

Continuous improvement means making work a little better, over and over, with the people who do the work leading the changes. The changes are small, each one is tested and checked, and the better method becomes the standard. It never ends, because every fix shows you the next problem.

The Japanese word for it is kaizen. The Lean Enterprise Institute's Lean Lexicon defines kaizen as continuous improvement through small, incremental changes, and credits Masaaki Imai with introducing the term to the wider world in 1986. Toyota's own description of its production system says every employee carries out small kaizen every day, and that only people can do it.

Small changes are cheap to try and easy to undo. A plant that treats improvement as a programme with an end date gets a burst of activity and then drifts back.

You will also see the phrase continual improvement. ISO 9001:2015 uses that wording. In a plant the two phrases are used for the same thing, and this guide treats them that way. If you are working towards certification, the ISO 9001 guide covers what the standard asks for.

The loop underneath: plan, do, check, act

The Lean Lexicon describes the kaizen process as based on PDCA. Whatever the size of the improvement, the same four stages repeat.

Plan, do, check, act: the question each stage answers

  1. 1PlanWhat is the problem and what do we expect the change to do?
  2. 2DoCan we try it small?
  3. 3CheckDid it do what we predicted?
  4. 4ActKeep it, change it or drop it?
Next problem
The cycle runs clockwise. Act ends one turn by updating the standard, and the next problem starts the next turn.
The four stages of PDCA
StageThe questionWhat it looks like on the floor
PlanWhat is the problem and what do we expect the change to do?Count the problem, find the likely cause, write down a prediction
DoCan we try it small?Test the change on one line or one shift
CheckDid it do what we predicted?Count again and compare with the number before
ActKeep it, change it or drop it?Update the standard if it worked, then pick the next problem

PDCA is also called the Deming cycle. According to the Lean Lexicon, W. Edwards Deming introduced the idea in Japan in the 1950s, building on an earlier cycle by Walter Shewhart. Some teams use the PDSA wording, where check becomes study. The PDSA cycle guide walks through one full turn, and the PDCA template gives you a sheet to write it on.

Why a standard has to come first

The Lean Lexicon quotes Taiichi Ohno: "There can be no kaizen without a standard." If three operators do a job three ways, nobody can say whether a change made things better, because there was no single method to compare with. A change that works also disappears the next time someone new is trained the old way.

So the order is: get the process stable enough to repeat, write down the current best method as standard work, improve it, then update the document. The standard is a baseline to improve from. It is not a rule that freezes the job.

Daily kaizen, kaizen events and projects

Improvement work comes in three sizes. Most plants need all of them, but daily kaizen is the one that makes it continuous.

Three sizes of improvement work

  • Daily kaizen

    Who does it
    Operators and their team leader
    How long
    Minutes to a few days
    Fits a problem that
    Sits inside one team's own area
    Example
    Mark the label roll position so every roll change lines up
    Where it goes wrong
    Ideas are raised and nobody answers

  • Kaizen event

    Who does it
    A cross-functional team taken off normal work
    How long
    Commonly five days
    Fits a problem that
    Needs one process redesigned in one go
    Example
    Rearrange a cell to cut walking and stock
    Where it goes wrong
    Gains fade because the standard was never updated

  • Improvement project

    Who does it
    A small team with a sponsor
    How long
    Weeks to months
    Fits a problem that
    Crosses departments or has an unknown cause
    Example
    Cut scrap on a product family with an A3 or DMAIC
    Where it goes wrong
    It drags on with no regular review
Daily kaizen is outlined because it is the one that happens every shift. Events and projects handle what a single team cannot fix in its own area.

The five day figure for a kaizen event comes from the Lean Lexicon, which also lists how events fail: the number of events becomes the target, the gains are lost soon afterwards, and specialists lead the work in place of the people who run the process. Use events for the problems that need them, and count results, not events. For individual ideas, kaizen ideas shows how to collect and answer them.

Which size of improvement work does this problem need?

Which size of improvement work

  • The problem

    It sits inside one team's own area

    Size

    Daily kaizen

    Raise it at the huddle and try it this week

  • The problem

    One process needs redesigning in one go

    Size

    Kaizen event

    Charter it, set the date, plan how the standard gets updated

  • The problem

    It crosses departments or the cause is unknown

    Size

    Improvement project

    Name a sponsor and review it on a fixed day

Start at the smallest size that fits the problem. Move up only when the cause is outside the team's own area.

Where the next improvement is hiding

  • The rework and scrap count from last week.
  • The stop that happens most often, not the longest one.
  • Steps where people wait for parts, tools or a decision.
  • Walking, reaching and searching that the job does not need.
  • Near misses and awkward lifts.
  • What new starters get wrong in their first month.

These are practical places to start, not a sourced list. Each gives a number you can count before and after.

A daily routine that keeps it going

Continuous improvement survives when it has a fixed place in the day. This routine fits around a ten minute start-of-shift huddle.

The daily improvement routine, from problem to standard

  1. 1

    See the problem where it happens

  2. 2

    Raise it the same day

  3. 3

    Decide at the huddle

  4. 4

    Try it small

  5. 5

    Check with a count

  6. 6

    Make it the standard and share it

Steps 1 to 3 happen on the same day. Steps 4 to 6 are one small turn of plan, do, check, act.
  1. 1

    See the problem where it happens

    Operators note what slowed them down or went wrong. The team leader walks the area. A gemba walk is for looking and asking, not for inspecting people.

  2. 2

    Raise it the same day

    Write it on the team board or an idea form in one or two lines: what happened, where, how often.

  3. 3

    Decide at the huddle

    The team picks what to try, who owns it and by when. Anything the team cannot fix goes up a level with a name against it.

  4. 4

    Try it small

    Test on one machine or one shift. Write down what you expect to see before you start.

  5. 5

    Check with a count

    Compare the number after with the number before. If it did not move, say so and try the next cause.

  6. 6

    Make it the standard and share it

    Update the work instruction, train the other shifts and tell the lines that have the same problem.

The daily kaizen routine and the daily huddle agenda put this on one page each.

A worked example

Illustrative example. A packing line reworks cartons when the label is applied crooked. In one week the team counts 38 reworks on 1,900 cartons, which is 38 / 1,900 = 2.0 percent. An operator points out that most of them come straight after a label roll change, because the new roll is lined up by eye. The plan: paint an alignment mark on the applicator and check one carton after every roll change. The prediction: fewer than 20 reworks a week.

Illustrative: label reworks a day, before and after the change
DayBeforeAfter
Mon94
Tue73
Wed82
Thu63
Fri83
Total3815

Cartons packed: 1,900 in the week before and 1,875 in the week after.

Label reworks a day, the week before and the week after

Example numbers
  • Mon: 9 reworks before, 4 after
  • Tue: 7 reworks before, 3 after
  • Wed: 8 reworks before, 2 after
  • Thu: 6 reworks before, 3 after
  • Fri: 8 reworks before, 3 after

Label reworks a day before and after the alignment mark: Monday 9 to 4, Tuesday 7 to 3, Wednesday 8 to 2, Thursday 6 to 3, Friday 8 to 3.

Grey ticks are the week before: 9, 7, 8, 6 and 8, which is 38 in all. The week after has 15. Every day is lower, so the drop is not one good day pulling the total down.

The week after, the count is 15 reworks on 1,875 cartons, or 15 / 1,875 = 0.8 percent. That is 23 fewer reworks. At about 3 minutes each, the line gets back 23 x 3 = 69 minutes a week. The prediction held, so the team adds the mark and the check carton to the roll change instruction and shows the other packing lines. The 15 that remain are the next problem to look at.

Nothing here needed a budget or an engineer, only someone to count and someone to listen to the operator. The kaizen savings calculator turns a saving like this into hours and money over a year.

What a continuous improvement culture takes

A culture is what people do when nobody is running a campaign. A few leader habits do most of the work.

  • They answer every idea, including the ones they turn down, and they do it within days.
  • They go to the floor on a schedule and ask what is getting in the way. Leader standard work keeps that from slipping when the week gets busy.
  • They give teams time to try things. Ten minutes a shift is enough to start.
  • They treat a problem raised as good news. If people are blamed for bad numbers, the numbers stop being reported.
  • They coach people to solve problems themselves. The Lean Lexicon describes the improvement kata, introduced by Mike Rother in Toyota Kata (2010), as a four step routine for exactly this.
  • They start in one area and get it working before spreading it. A model area gives the rest of the plant something real to copy.

Continuous improvement tools, matched to the problem

Pick the tool from the problem in front of you.

Which tool fits which problem
The problemTool to reach forWhere to learn it
The area is cluttered and things get lost5S5S guide
A defect or stop keeps coming back5 Whys or a fishbone diagramRoot cause analysis
The problem is bigger than one teamA3 reportA3 problem solving
You have a change to testPDCA or PDSAPDSA cycle
You do not know where the problems areGemba walkWhat is a gemba walk
A station cannot keep up with demandTakt time and line balancingTakt time
Parts run out or pile up between stepsKanbanKanban guide

Lean tools lists the wider set, and the problem solving methods guide helps you choose between A3, 8D and DMAIC. If you are asking what software does for all this, that is a separate question, answered in what is continuous improvement software.

How to tell whether it is working

  • Ideas implemented per person, not ideas submitted. A full suggestion box that nobody empties is a warning sign.
  • Days from an idea being raised to a decision on it.
  • The share of improvements that ended in an updated standard.
  • The result on the measure the team owns, such as scrap, rework, stops or changeover time. See manufacturing KPIs for definitions.
  • Whether last quarter's gains are still there when you go and look.

If you run improvement in a plant and want to compare notes, LeanSuite has an open state of continuous improvement survey. It takes under five minutes.

Common mistakes

  • Running events with no daily routine underneath. The event team leaves and the area slides back.
  • Leaving improvement to a central team. Engineers can help, but the people who do the job have to own the change.
  • Skipping the check. A change that was never measured is an opinion.
  • Not updating the standard, so the gain lasts until the next shift change.
  • Starting everywhere at once. Thin effort across a whole site rarely gets any one area to the point where it sustains itself.
  • Chasing only cost. Teams lose interest quickly when every idea is judged on savings and none on making the job safer or easier.

Continuous improvement software

Run continuous improvement in LeanSuite

LeanSuite takes each Kaizen, CAPA, CapEx or engineering project from idea to verified savings, with your own methods, phases and approval rules.

See Continuous improvement softwareBest continuous improvement software

Go deeper

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

All our articles on this subject are in the kaizen and continuous improvement topic.

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FAQ

Questions about continuous improvement

  1. It is the ongoing practice of making small improvements to how work is done, led by the people who do the work. A team spots a problem, tests a change using plan, do, check, act, and writes the better method into the standard so the gain holds. Then it picks the next problem.

  2. The ones used most on a shop floor are PDCA for testing a change, 5S for workplace organisation, 5 Whys and the fishbone diagram for root causes, the A3 report for larger problems, gemba walks for finding problems and standard work for holding the gain. Choose the tool from the problem, not the other way round.

  3. Start in one area. Give the team a daily huddle, a place to raise problems and a few minutes a shift to try changes. Answer every idea quickly, go to the floor on a schedule, treat a raised problem as good news and update the standard after each gain. Spread to other areas once the first one runs without being pushed.

  4. Kaizen is the Japanese word that is translated as continuous improvement, so in a lean plant they mean the same thing. In everyday use, kaizen often refers to a specific activity such as a kaizen event or a single idea, while continuous improvement refers to the whole practice.

  5. There is no single official list. Sources number the steps differently, and the Lean Enterprise Institute describes kaizen as a process based on plan, do, check, act. The routine in this guide has six steps: see the problem, raise it the same day, decide at the huddle, try it small, check with a count, and make it the standard.

  6. A packing team notices that most crooked labels follow a label roll change. They paint an alignment mark on the applicator and check one carton after each change. In the illustrative example in this guide, reworks fall from 38 a week to 15, and the mark and the check are added to the work instruction.

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