Jidoka
The Toyota Principle of
Building Quality into the
Process
Copyright © 2020
Mohammed Soliman
All rights reserved
Mohammed Hamed
Ahmed Soliman
Contents
Introduction ........................................ 5
Going back into history ...................... 7
Detect and signal abnormalities ........ 9
Jidoka is a principle of building in
quality not losing production! ......... 14
Two different concepts of Jidoka
principle ............................................. 19
Analyzing quality failures to eliminate
root causes ......................................... 24
References: ........................................ 34
Introduction
Jidoka is one of the main pillars
of the TPS. The TPS is
presented as a house with two
pillars. One pillar represents
just-in-time (JIT), and the other
pillar the concept of Jidoka.
Take away any of the pillars
holding up the roof, and the
entire system will collapse.
Take out quality, and there is
no TPS. Jidoka is a principle of
building quality for
customers—not inspecting
quality. Building quality mean
making it right the first time. If
you are making defective
products or using unacceptable
quality standards and filtering
these defects out through an
inspection system, there is no
building quality—and no
Jidoka. You are just catching
the mistakes made in the
manufacturing process. This
cost a lot of money and
resources and puts the business
at risk.
Yet many companies focus on
the mechanisms of
implementation--one-piece
flow, pull production, takt time,
standard work, kanban--without
linking those mechanisms back
to the pillars that hold up the
entire system. JIT is fairly well
understood, but jidoka is key to
making the entire system stick.
A lot of failed implementations
can be traced back to not
building this second pillar.
Going back into history
The principle's origin goes back
to 1902 when Sakichi Toyoda
invented a simple but ingenious
mechanism that detected a
broken thread and shut off an
automatic loom. That invention
allowed one operator to oversee
the operation of up to a dozen
looms while maintaining
perfect quality. But the system
goes much further.
Detect and signal
abnormalities
To build quality into the
process machines have to be
designed to detect defects when
they occur and automatically
stop production so an employee
can fix a problem before the
defect continues downstream.
One of Taiichi Ohno's
famous quotes is "get the
factory to work for the business
the same way the human body
works for the person". This is
to say that when your body
needs more blood, you don't
have to tell the heart to pump. It
does so autonomic ally. Jidoka
is the concept that you need to
design processes and systems
so that when errors occur,
people respond immediately in
support. So, at midnight on a
Saturday, how do your systems
respond to errors? Do the errors
come to light immediately and
problem solving begin or does
everything wait until Monday?
Jidoka would drive you to
ensure that abnormalities are
made immediately visible at all
times and it would drive you to
ensure the associates who
respond to that abnormality
have the capability and
authority to fix it.
Toyota uses an andon cords
or pull cords which can bring
the entire assembly line to halt.
Every team member has the
authority to stop the line every
time they see something out of
standard. As Liker explained in
Toyota Way, “jidoka referred to
as automation-equipment
endowed with human
intelligent to stop itself when it
has a problem.”
Jidoka culture
My first exposure to Jidoka was
in a manufacturing company in
Egypt that tried to apply this
principle to improve quality
and safety. In this factory, if
you didn’t run the production
100% of the shift, you had to
explain to the divisions. Quality
and preventative maintenance
are compromised in favor of
quantity. By building a culture
of stopping to fix problems,
you are encouraging the
workforce not to hide their
problems that are actually
killing profitability and causing
inefficiencies. You should be
planning for a long-term
productivity.
Jidoka is a principle of
building in quality not
losing production!
Unfortunately, and like many
other companies there is a
wrong misunderstand about the
concept and how it operates. As
Liker illustrated in The Toyota
Way when Toyota competitors
started to use the andon system,
they made the same mistake of
assuming the line-stop system
was hardwired to each and
every production line. So when
the button is pushed, the entire
assembly line like comes to a
screeching halt. At Toyota, the
principle of andon is worked
remarkably different. When an
operator in a workstation
pushes an andon button, that
workstation will light up in
yellow typically like the traffic
light, but the line will continue
moving. The team leader has
until the product moves into the
next workstation zone to
respond, before the andon turns
red and the line segment
automatically stop. As Liker
explained, in Toyota this likely
is to be a matter of 15-30
seconds on an assembly line
making cars at one minute. In
that time the team leader might
immediately fix the problem or
note it can be fixed while the
car is moving into other
workstations and push the
button again, canceling out the
line stoppage. Or the team
leader might conclude the line
should stop.
In that system, that are many
considerations and tips
presented in The Toyota
Way:
1. The team leader has to be
trained as well on a
standardization procedure on
how to respond to andon calls.
2. The assembly line should be
divided into segments with
small buffers of products in
between (in Toyota this buffer
is typically 7-10 cars). Because
of the buffer, when a line
segment stops, the next line can
keep working for about 10
minutes using the buffer and
before the entire plant is shut
down and rarely does it do
shutdown.
3. The purpose of andon is to
build in quality, not to lose
production. Toyota achieved
the purpose of andon without
taking needless risks of lost
production.
4. Some manufacturers assign a
worker to watch the machine
for error. This is a waste of the
human precise time! Operator
that is watching the machine for
error is a pure waste and you
have to develop a method (like
Toyota andon) so problems are
surfaced automatically when
they occur.
Two different concepts of
Jidoka principle
The first concept is to separate
man from machine. It was
normal in the original parent
company for a single young
woman to operate many
machines since they were
automated. So when Mr. Ohno
came to the automotive
company after WW II and saw
one man operating one machine
tool he thought that it was
strange and inefficient.
He embarked upon a path of
breaking down the notion of
one man one machine in the
engine shops. Instead of
“monitoring” machines the
operator was to walk between
two machine tools and keep
them both up and running.
Then three machines and four
machines and so on.
The second concept of
Jidoka is of course the concept
of building in 100% quality
every time at the process and
not inspecting it in later
downstream.
This means you have to
have a highly capable process
and know how to maintain all
the key variables in the process
so that a good part is made
every time. If a problem occurs
the machine should stop right
away.
The main purpose of Jidoka
principle is to discover quality
problems at earlier stages, find
the root causes and eliminate
the problem from recurring
again in the future. By doing so
you are saving both your
customer and your business. If
a defected product is passed to
customer so this is a problem
and because customers are what
keep you in business, you have
to build quality for them. This
is one of the main lean goals.
The goal is to prevent a quality
issue that is reducing
productivity every day and
killing your capacity,
decreasing value, increasing
costs and reducing safety. Lean
encourage you to make it right
from first time and this is why
surfacing problems is important
and can’t be done without a
single-piece-flow system.
Inspecting defects before they
pass to the customer is not
really the main goal of lean.
But having a system that allow
information to flow, problems
to surface so they can be fixed
immediately is the goal. Root
causes should be identified and
eliminated through kaizen.
With lean, there is no or very
little inventory buffer, so when
process A stops process B will
stop too. This allow problems
to be noticed quickly and
eliminated. There will be no
more underlying costs and
hidden wastes.
You can’t compromise
quality. Quality problems are
one of the greatest wastes in the
process. Quality is what adds
value for your customer and
keeps you in business and
defective products that reach
the customer can lead to
complete business loss.
Analyzing quality failures
to eliminate root causes
Basically, it is not difficult to
know how many defective
products are produced, as a
simple sheet of paper can
record this information. What is
not easy to know is what
caused the defects. Finding out
can require intensive efforts to
understand the source of
variation that is causing the
quality problem. And this is
why one-piece flow improves
quality. When problems are
quickly noticed, they can be
solved and eliminated
immediately before they
become chronic and costly.
Finding problems in quality
is an important function of
management. When faced with
issues, many practitioners go
straight to a complex tool like
Six Sigma to find the sources of
variation. But often, the simple
approach of go and see
(referred to gemba) could find
the real cause easily.
Monitoring how the operator is
producing, revising the work
against the standard, and
involving the technical team
could clear up many things.
Comparing the machine or
process with another one that
produces the same part with
fewer defects can make the
analysis even quicker and
easier.
At Toyota, managers use very
few complex statistical tools for
quality. They usually stick with
go and see, mistake proofing
techniques, a simple analysis
tool like Pareto and problemsolving approaches like the
five-whys, as Liker reported in
his best-selling book The
Toyota Way.
Quality improvement
techniques
There are many tools to
accomplish the quality goals at
every aspect of the process.
There are many tools that will
help prevent quality problems
before they occur and allow
you to plan for an error-free
product. Poka Yoka which is a
Japanese term, also refers to
mistake-proofing is an effective
tool to prevent human-errors. I
have personally used it many
times when conducting a failure
mode effect analysis process.
This tool can improve quality
in many business processes
include service, manufacturing,
and design. Inventory control is
another technique that is
usually associated with any
mistake proofing device.
There are large number of
applications in real world
regarding the use of mistake
proofing in product design.
Examples: Limit switches to
assure a part correctly placed or
fixture before process is
performed; part features that
only allow assembly the correct
way, unique connectors to
avoid misconnecting wire
harnesses or cables, part
symmetry that avoids incorrect
insertion.
Unfortunately, companies
invest on technologies
mistakenly thinking that
technology can prevent errors.
Technology can only support
people and systems to prevent
errors when there are good
management system and people
are trained on problems solving
and how to react immediately
to abnormalities.
To assess a product failure and
determine failure mechanism
that need mistake-proofing you
may need the use of a technique
like failure mode and effect
analysis.
Failure mode effect analysis
(FMEA) is a process of
assessing the failure risk based
on its occurrence, severity, and
detectability. The more
detectable methods we have in
the system to detect and predict
failure, the lower the risk of the
product failure. FMEA and if
used properly, can be a good
tool in improving quality. An
article that I wrote in the last
year in the Industrial
Management Magazine
“Analyzing Failure to Prevent
Problems” can illustrate this as
well. Many organizations only
use FMEA during the design
stage, but FMEA can be really
used in manufacturing, design,
service and maintenance.
Lean is not a toolkit for
manufacturing to lower costs
for profitability. Lean is a long
term strategy to satisfy
customers through better
quality and lower costs.
Engineering a product that
solve your customer’s usage
problems is a legitimate lean
goal. Lean is about innovation
and creativity. If you can
manufacture defect-free
product or build quality into the
design, this will help satisfy
customers and increase their
confidence.
References:
Ahmed, M. H. (2013). OEE
Can Be Your Key: Change
Formula for Equipment
Availability to Improve
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Engineer 45(8): 43.
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About the Author
Mohammed Hamed Ahmed
Soliman is an industrial
engineer, consultant, university
lecturer, operational excellence
leader, and author. He works as
a lecturer at the American
University in Cairo and as a
consultant for several
international industrial
organizations.
Soliman earned a bachelor
of science in Engineering and a
master’s degree in Quality
Management. He earned postgraduate degrees in Industrial
Engineering and Engineering
Management. He holds
numerous certificates in
management, industry, quality,
and cost engineering.
For most of his career,
Soliman worked as a regular
employee for various industrial
sectors. This included crystalglass making, fertilizers, and
chemicals. He did this while
educating people about the
culture of continuous
improvement.
Soliman has lectured at
Princess Noura University and
trained the maintenance team in
Vale Oman Pelletizing
Company. He has been
lecturing at The American
University in Cairo for 6 year
and has designed and delivered
40 leadership and technical
skills enhancement training
modules.
Soliman is a member at the
Institute of Industrial and
Systems Engineers and a
member with the Society for
Engineering and Management
Systems. He has published
several articles in peer
reviewed academic journals and
magazines. His writings on lean
manufacturing, leadership,
productivity, and business
appear in Industrial Engineers,
Lean Thinking, and Industrial
Management. Soliman’s blog is
www.personal-lean.org.