1. P R E P A R E D B Y :
M R . H A R D I K A . P A T E L
A S S T . P R O F .
M E C H A N I C A L E N G I N E E R I N G D E P A R T M E N T
Atmiya Institute of technology
and Science, Rajkot
POKA YOKE AND JIDOKA
3. Poka Yoke
Zero Defects through Mistake-Proofing
Methods that help to avoid mistakes in work caused by choosing the
wrong part, leaving out a part, installing a part backwards, etc. Also called
mistake-proofing, error-proofing and baka-yoke (fool-proofing).
The term poka-yoke was applied by Shigeo Shingo in the 1960s to
industrial processes designed to prevent human errors.
Shingo redesigned a process in which factory workers, while assembling a
small switch, would often forget to insert the required spring under one of
the switch buttons. In the redesigned process, the worker would perform
the task in two steps, first preparing the two required springs and placing
them in a placeholder, then inserting the springs from the placeholder into
Defects occur when the mistakes are allowed to reach the
5. Types of poka-yoke
Contact method where a sensor determines the presence of
a part in a process and if the part is missing, it prevents the
process from continuing. The sensors could be physical
sensors or energy sensors such infrared.
Fixed-value method is a form of poka-yoke that uses a
sensor to determine whether a process is complete by the
number of parts that have been used or the number of process
steps taken. If the right number of steps or parts have not
been used, this indicates an error and the process is stopped.
This method is also known as the counting method of mistake
Motion-step method uses a sensor to determine whether
all the prerequisite process steps have been undertaken. If a
step in the process has been missed, a signal is sent to the
subsequent process to stop. This forces a correction of the
problem before the process can continue and is a very
effective error-proofing technique.
6. Benefits of Poka Yoke
Quality processes resulting in quality products. It is very hard for a
process that is not of high quality to result in quality products or
services. All processes must be capable of achieving value for the
customer and this is possible through elimination of waste.
Effective teams who work in a coordinated manner so as to deliver
value to the customer. Such teams look at the system as a whole and
know their what roles they have to play so as to achieve the overall
Problem solving culture where there is no blaming when problems
occur, but a concerted effort to resolve the real issues. This culture
allows constant learning to take place within an organization
because there is no finger-pointing when a problem occurs.
Solving the root cause guarantees that it will not recur in the
future. This is achieved by conducting a root cause analysis to get
to the real reason why a problem occurred.
7. Benefits of Poka Yoke
First time quality is an important principle because it ensures
that every effort is made to achieve quality within process.
This is in contrast to a culture that continuously pushes out
parts irrespective of the quality because there will be a
reworking if bad parts are produced
Waste elimination is at the heart of lean thinking because
product quality improves and delivery times and costs are
reduced. Waste in lean thinking is defined as an action or
activity that consumes resources but does not add value to the
Continuous improvement of the solutions. This incremental
improvement takes a cyclical pattern of problem identification,
problem analysis, solution implementation and improvement.
Jidoka is about quality at source, or built in quality; no
company can survive without excellent quality of product
and service and jidoka is the route through which this is
Jidoka highlights the causes of problems because work
stops immediately when a problem first occurs.
Jidoka sometimes is called automation with human
Toyoda's innovation let one operator control many
machines. In Japanese, jidoka is a Toyota-created word
pronounced exactly the same as the Japanese word for
automation, but with the added connotations of humanistic
and creating value.
Jidoka is one of the two pillars of the Toyota Production
System along with just-in-time.
12. Development of Jidoka
Initially Jidoka invented by Sakichi Toyoda in 1896.
A simple device that could stop the shuttle on an automatic
textile loom if the thread broke.
It consist of:
Discover an abnormality in the process
STOP alerted the operator to a problem
Fix the immediate problem
Investigate and correct root cause
This principle became known as automation with a human
The principles that were applied to machines with
Automation were applied to the whole process by Taiichi
14. Benefits of JIDOKA
The first benefit is the reduction of repair costs.
The second benefit of Jikoda is the reduction of
recall costs, if the products and goods are produced
with machines only, there may be inherent defects
which may not be detected through sampling.
The third benefit of Jikoda is the minimization of law
suits and compensations to the consumers as the
goods and products being sold are of high quality
hence reducing the company’s liability.