POKA-YOKE REPORT IN PDF FORM

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LIST OF CONTENTS
TITLE PAGE NO.
1. INTRODUCTION 1
1.1 Overview 1
1.2 What Is Poka-Yoke? 2
1.3 Need Of Poka-yoke 3
1.4 Technical Aspects Of Poka-Yoke Method 4
1.5 When To Use It? 6
2. COMMON DEVICES USED IN POKA-YOKE SYSTEMS 7
3. TYPES OF POKA-YOKE 10
3.1 Poka-yoke Methods 10
3.1.1 Shut down Method 10
3.1.2 Prevention Method 10
3.1.3 Control Method 11
3.2 How To Use It? 11
4. METHODOLOGY OF POKA-YOKE 12
4.1 Methods 12
4.2 Methods Of Obtaining Poka-Yoke 14
5. EXAMPLES AND CASE STUDIES OF POAK-YOKE 15
5.1 Examples Of Poka-Yoke 15
5.1.1 Alarm Systems 15
5.1.2 Connector And Charger 15
5.1.3 Finger Print Identification 16
5.1.4 Dialysis Machine 17

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5.2 Case Study of Poka-Yoke 18
6. CHALLENGES AND LIMITATIONS OF POKA-YOKE 22
6.1 Challenges Of Poka-yoke 22
6.2 Characteristics Of Poka-Yoke 22
6.3 Qualities Of Good Poka-Yoke 23
7. CONCLUSION 24
8. REFERENCES 24

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LIST OF FIGURES
TITLE PAGE NO.
1.1 USB Cable 1
1.2 Cost and Zero defects relationship 4
2.1 Sensing object interrupts light 8
2.2 Vibration sensor 8
4.1 Poka-Yoke system design 13
5.1 Alarm Systems 15
5.2 connector and charger 16
5.3 Finger print Identification device 16
5.4 Dialysis machine 17
5.5 Poka-Yoke simple practical implementation 18
5.6 Location of metal chips and punching location 19

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ABSTRACT
In today’s competitive world any organization has to manufacture high
quality, defect free products at optimum cost. The new culture of total quality
management, total productive management in the manufacturing as well as service
sector gave birth to new ways to improve quality of products. By using various tools
of TQM like KAIZEN, Six Sigma, JIT, JIDCO, POKA YOKE, FMS etc.
organization is intended to develop quality culture.
During actual manufacturing of any product there are too many simple and
smonotonous steps which are carried out by operators. These monotonous work
operations result in to mental fatigue and lack of interest in work which ultimately
causes silly mistakes of operators and we know that human is prone to errors even
though he doesn’t want it. To avoid these simple mistakes, poka yoke concept play
important role. By implementing some simple solutions we can avoid mistakes. The
long term success of poka yoke gives output of saving time and we release the work
pressure on mind of worker. We can use creativity and special skills of workers for
more creative operations instead of increasing pressure for monotonous activities

POKA-YOKE 132U1A0479
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GEETHANJALIINSTITUTE OF SCIENCE AND TECHNOLOGY
Gangavarm(v), kovur(M), Nellore
CHAPTER- 1
INTRODUCTION
1.1 Overview:
Nowadays, each and every company wants profit, high productivity, value in market.
There are slogans in most factories stating defect reduction targets, but the ultimate aim should
always be zero defects. "POKA-YOKE" is a vital factor in eliminating defects. Poka-yoke is a
concept in total quality management which is related to restricting errors at source itself. It deals
with "fool-proofing" or "mistake-proofing". A poka-yoke is any idea generation or mechanism
development in a total productive management process that helps operator to avoid (yokeru)
mistakes (poka). Main aim of Poka Yoke concept is to make whole system error proof that
means no one can make mistake although some one wants to make mistake sin tentionally. It
eliminates the defects or faults. This term was coined by Shigeo Shingo in 1960sfor the part of
Toyota Production System. The aim of Poka-yoke is to design the process so that mistakes can
be detected and corrected immediately, eliminating defects at the source. A methodical approach
to build up Poka-Yoke countermeasures which consists in a three step analysis of the risks to be
managed:
1. Identification of the need
2. Identification of possible mistakes
3. Management of mistakes before satisfying the need.
These steps are taken into consideration while thinking about implementation of Poka Yoke
system in any field because this methodology remains same at all the situations and conditions.
Figure 1.1: USB cable
Above figure 1.1 shows the concept of the Poka Yoke system. In upper diagram, size of both
holes are same, therefore there may be mistake of putting positive terminal into negative hole but

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on the other hand, in lower figure, the sizes of both the holes are different which results in
avoiding the misplacement of the terminal into wrong hole.
1.2 What is POKA-YOKE?
Poke-yoke (Mistake proofing) is a Japanese improvement strategy for mistake-proofing
to prevent defects (or Nonconformities) from arising during manufacturing processes. Poka-yoke
is a preventive action that focuses on identifying and eliminating the special causes of variation
in manufacturing processes, which inevitably lead to product defects or nonconformities. This
concept was initially called Idiot Proofing but it was understood that this name may heart
workers so term Mistake Proofing was coined by Shigeo Shingo. Poka-yoke gives a strategy and
policy for preventing defects at the source. Poka-yoke solutions are not only the cost-effective
but also easy to understand and apply. Mistake proofing is one of the important tools to add to
any organization’s Continuous improvement.
In short poka-yoke is a continual improvement strategy that offers a way to move the
QMS (quality management system) towards a higher level of performance. The poka-
yoke(mistake proofing) concept was generated in the mid-1960s by Shigeo Shingo who is
Japanese industrial engineer. Shingo was working for the Toyota and other Japanese companies,
where he developed entire Manufacturing systems focused on achieving zero defects in
production and gave birth to this revolutionary work. The basic concept behind poka-
yoke(mistake proofing) is that it is not acceptable and allowed to produce even a small amount
of nonconforming product. To stay in market and to become a whole world-class competitor, an
organization must go with new strategy and technology along with side by side practice of
producing zero defects.
Poka-yoke methods are the easy and simple concepts for achieving this goal and are a
key component of the continual improvement strategy in many leading Japanese companies on
this moment. Poka-yoke (fool proofing) is one of the presentations of “good kaizen”, or superior
continual improvement because of its preventive nature. A poka yoke device or solution is apply
any mechanism or idea that either avoids the mistake from being made or makes the mistake
easily identify at a glance. The ability to find mistakes at a glance is important because, as
Shingo states, "The causes of defect lie in workers errors, and defects are the results of
neglecting those errors. It follows that mistakes will not turn into defects if worker errors are
discovered and eliminated beforehand"[Shingo 1986. He also adds to this that "Defects arise

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because errors are made” the two have a cause-and-effect relationship. Yet errors will not turn
into defects if feedback and action take place at error stage During actual manufacturing of any
product there are too many very simple and monotonous steps which are carried out by
operators.
These are monotonous work operations result in to mental fatigue and lack of interest in
work which ultimately causes silly mistakes of operators and we know that human is prone to
errors even though he doesn’t want it. To avoid these simple mistakes by poka-yoke concept
play important role. By implementing some simple solutions we can avoid mistakes. The long
term achievement of poka- yoke gives output of saving time and we release the work pressure on
mind of worker. We can use creativity and innovative skills of workers for more creative
operations instead of increasing pressure for monotonous activities This involvement of
everyone in organization is basic need to rise roots of quality culture in the organization.
1.3 Need of POKA-YOKE
When any organization decides to implement the lean manufacturing then one of the
objective is to reduce scrap because no one is interested to compensate extra inventory on
account of scrap. As per philosophy of lean manufacturing it focuses on speed of production and
productivity also. In order to follow this concept of speed we should prevail against defects and
rework. To the increase profit percentage the cost pressures always become headache for top
management so they never accept continued mistakes like scrap, rework, lateness etc. out of
tolerance instead they are aiming to achieve value of zero in this segment. When customers of
any company buys product they rightfully expect defect free products and conventional 100%
inspection or statistical process control don’t insure 100% defect-free products (zero defect).
Hence we are going to root cause of any problem and avoiding it which gives us defect free
product. In the above discussion concludes that to get defect free products one should go with the
concept of Poka-Yoke. Below graph plotted between cost/defects.

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Fig 1.2: cost& zero defects relation
1.4 Technical aspect of Poka-Yoke method
Poka-Yoke technique can be applied both to prevent causes, which will result in subsequent
occurrences of errors and to carry out inexpensive control determining whether to adopt or reject
the product. It is not always 100% probability elimination of all errors, in such cases it is the task
of Poka-Yoke methods is detection as soon as possible. Analyze the process of product defects
formation noted that between a mistake resulting from the defect is yet one, the potential
possibility: The observation mistake and its correct. It is therefore the proposal -method for
reducing defective is planning conditions in which error may not happen, or will be immediately
visible and captured. Take into account the above Shigeo Shingo developed a achieving "zero
defects" in industrial conditions, i.e. in such a way as simple and cheap. Was itself at the matter,
that it is not possible to reduce the defects using random checks. It is necessary to the total
control - 100% control.
Shigeo Shingo adopted assumptions like in the case of confusion applying the statistical
process control is ineffective, monitoring and control the poka-yoke should be autonomous, i.e.
operations carried out by the contractor without intervention from the outside, 100% - the total,
cheap. Shigeo Shingo has analyzed in detail the process formation of defects and errors from the
source to effect. He said that mistake from the producer becomes defect for the user in this
moment when the customer unnoticed this defect. It should be therefore a maximum reduced and
speed up action coupling back, and so on as soon as possible –and simplest should be detect
errors (inspection of information, "after the fact", typical for statistical control).
1. At the earliest as soon as possible signal error before it become the defect (in the

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2. Eliminate possibility of the occurrence error (inspection at source, verify the conditions under
which runs the operation in order to eliminate the possibility formation error).
The Poka-Yoke is a technique for avoiding human error at work. A defect exists in either of two
states; the defect either has already occurred, calling for defect detection, or is about to occur,
calling for defect prediction. Poka-yoke has three basic functions to prevent or reduce defects:
shutdown, control, and warning.
Categories of poka-yoke devices
Poka-yoke devices fall into two major categories: prevention and detection.
A prevention device engineers the process so that it is impossible to make a mistake at all. A
classic example of a prevention device is the design of a 3.5 inch computer diskette. The diskette
is carefully engineered to be slightly asymmetrical so that it will not fit into the disk drive in any
orientation other than the correct one.
Prevention devices remove the need to correct a mistake, since the user cannot make the
mistake in the first place.
A detection device signals the user when a mistake has been made, so that the user can
quickly correct the problem. The small dish used at the Yamada Electric plant was a detection
device; it alerted the worker when a spring had been forgotten. Detection devices typically warn
the user of a problem, but they do not enforce the correction.
We are surrounded every day by both detection and prevention poka-yoke devices, though we
may not usually think of them as such. My microwave will not work if the door is open (a
prevention device). My car beeps if I leave the key in the ignition (a detection device). At few
years ago, some cars were designed not to start until the passengers had buckled their seat belts
(a prevention device); but this mechanism was too intrusive and was replaced by a warning beep
(a detection device).

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1.5 When to use it?
Poka-yoke can be used wherever something can go wrong or an error can be made. It is a
technique, a tool that can be applied to any type of process be it in manufacturing or the service
industry.
Errors are many types –
1.Processing error : Process operation missed or not performed per the standard operating
procedure.
2. Setup error: Using the wrong tooling or setting machine adjustments incorrectly.
3. Missing part: Not all parts included in the assembly, welding, or other processes.
4. Improper part/item: Wrong part used in the process.
5. Operations error :Carrying out an operation incorrectly; having the incorrect version of the
specification.
6. Measurement error: Errors in machine adjustment, test measurement or dimensions of a part
coming in from a supplier.

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CHAPTER-2
COMMON DEVICES USED IN POKA-YOKE SYSTEMS
The common devices used in Poka –Yoke systems are:
1. Guide pin
2. Blinking light and Alarms
3. Limit Switches
4. Proximity switches(sensor)
Guide pin:
Guide pins are often used as a means of ensuring the accuracy with which machined parts
are stacked on top of one another. They may also be used as a means of correctly aligning one
component of a two-part system with the other. The pin may actually come in the form of a bolt
with a tapered end or even in the shape of a bullet with the corresponding piece containing metal
or plasticized grommets at every contact point. The grommets would allow the guide pins to
penetrate the secondary component in order to ensure the accurate configuration of the two parts
being put together.
Blinking light and alarm:
Modular design with sturdy housing for all indoor and outdoor applications in tough
conditions wherever machine status needs to be displayed and warning signals given.
Limit Switch:
A limit switch is an electromechanical device that consists of a actuator mechanically
linked with a set of contacts. When any object comes into contact with the actuator, the device
operates the contacts to make or break an electrical connection. Limit switches are used in a
different type of applications and environments because of their ruggedness, ease of installation,
and reliability of operation. Limit Switch can determine the presence / absence, passing,
positioning, and end of travel of an object. Limit switch were first used to define the limit of
travel of an object; hence the name "Limit Switch".

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Sensor:
A sensor is a transducer whose purpose is to sense (that is, to detect) some characteristic
of its environs. It detects events or changes in quantities and provides a corresponding output,
generally as an electrical or optical signal; for example, a thermocouple converts temperature to
an output voltage. But a mercury-in-glass thermometer is also a sensor.
Sensing device are traditionally used in poka-yoke
i. Physical contact device
ii. Energy sensing device
(a) Photo electric Sensor
The transmitter and receiver of the thru-beam sensor and housed in different cases that
are separated from each other the Emitter(E) Transmits directly to the receiver(R). If object(O)
interrupt the light beam, the receiver voltage drop and the switching function is initiated. The
thru-beam sensor are used to monitor production and packing lines to measure full state in
transparent container or as a safety measure for door and hazardous area.
Fig2.1 : Sensing object interrupts the light
(b)Vibration sensor
Despite the advances made in vibration monitoring and analysis equipment, the selection
of sensors and the way they are mounted on a machine remain critical factors in
Fig2.2 : Vibration sensor
determining the success of any monitoring program. Money saved by installing inferior sensors
is not a prudent investment since the information provided about the machine of interest often is

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not accurate or reliable. Poor quality sensors can easily give misleading data or, in some cases,
cause a critical machine condition to be completely overlooked.

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CHAPTER-3
TYPES OF POKA- YOKE
3.1 poka yoke methods:
The Poka-Yoke is an innovative technique for to keep away human error at work. A
defect or imperfection exists in either of two states; the defect either has already occurred in that
case calling for defect detection, or is about to occur in that case calling for defects prediction.
The technique starts by analyzing the process for potential problems, identifying parts by the
characteristics of dimension, shape & size and weight, detecting process deviation from nominal
procedures and norms. Depending on the basic functionality Poka-yoke has three types
1. Shutdown Poka yoke
2. Control Poka yoke
3. Warning Poka yoke
Shutdown (Prevention) Method
In shut down i.e. prevention method Poka-yoke devices checks critical process
parameters and shut down the process when a situation moves out of the tolerance zone, it is
indicates of a defective product has either been produced or is about to be produced. That is well
known note that prevention is always better than cure. By implementing shutdown method we
can assure about 100% defect free products. It has 0 % chances to produced defective products,
up to this level we can reliance on it. E.g. Use of fuse in the electric circuit. When there is an
short circuit then fuse is operated and cut down the supply of electricity resulting in avoiding any
further accidents.
Control method
In control method Poka-yoke devices are regulatory in working which are installed on
process equipment and/or Work pieces which make it impossible to produce defects and/or to
flow a nonconforming product to the next process. As like shut down is an method control
method gives 100% defect free products. The control make certainty that if there is any defect, it
is not coming outside the production line and does not reach to the customer. E.g. To avoid any
wrong job loading in reverse direction on machine we can provide work rest for the job which
will avoid wrong job loading.

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Warning (Alert) method
This is the method which makes the operator conscious about something is going wrong.
The Mechanism or simple idea is generated in such a way that Poka-yoke devices indicate or
shows to a worker that a defect has been produced. When operators get such warning then he
must immediately interfere the process to correct the process (es) responsible for causing the
defect. In case of irresponsible behavior of operator irrespective of getting warning notice the
next products will continue the same defect and produce nonconforming products. In short again
warning (alert) method depends on human nature and behavior.
It is concluded that alert method gives 30% of the guarantee of good products. Actually
warning method tells about existence of defect but does not assure and does not produce 100%
quality. The common warning method are use of blinking light and use of beeping sound as
alarm alert. e.g. Beeping sound or flashing of light in ATM machine after removing ATM card
from machine to warn operator that he is safe and ensure that card is not in machine. Once top
management decides to implement TPM culture in organization then to compensate for defect
free products successfully one should follow the methodology of Poka-yoke.
3.2 HOW TO USE IT ?
Step by step process in applying poka-yoke:
1. Identify the operation or process
2. Analyse and understand the ways in which a process can fail.
3. Decide the right Poka-yoke approach, such as using a,
 Shut out Type: Preventing an error being made, or an
 Attention Type: Highlighting that an error has been made.
4. Determine whether a
 Contact Method
 Constant Number or Counting Method
 Motion-Sequence Method
5. Trial the method and see if it works.
6. Train the operator, review performance and measurement success.

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CHAPTER-4
METHODOLOGY OF POKA-YOKE
The methodology of poka-yoke are:
1. Identify Problem
2. Observation at workstation
3. Brainstorming for idea
4. Select best idea
5. Implementation Plan and Implementation
6. Monitor and sign off
Step 1: Identify problem
In this stage the complaints coming from the customers (Both internal and external
customer) are collected. The principle of standard is determined by considering various criteria’s
like number of complaints from the customer& PDI( pre dispatch classify), the quantity of
defects detected by quality control, materiality defects (their impact on the customer, costs,
implemented process) and then data is collected broadly. As per analysis all results of the
collected data company plans for developing poka yoke system for the selected problem. In this
way in first stage the problem is selected.
Step 2 :Observation at work stations
In this step the actual on site study of the problem is carried out. The causes behind the
problem are sort out by using fishbone diagram (fishbone diagram is cause and effect diagram
given by Japans management guru Ishikawa).The causes may be related to man skill, machine,
material or method accordingly the complete sorting is carried out.
Step 3: Brainstorming for Idea
This is a technique to capture all creativity and skills of employee’s .In brainstorming
session the problem under study is put forward to committee. Then study problem given by all
members and give various solutions to avoid that defect. As each person has one uniqueness this
step concludes with various alternative solutions for same problem.

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Step 4: Select best ideas
After getting all various alternative solutions it is time to select best one out of all
collected solutions. Criteria for selection may be cost, problem create after installation, time
required, changes in existing system, opportunity to develop new solutions, simplicity in
operation etc. By referring all selection criteria’s committee concludes With one best solution.
Step 5: Implementation plan and implementation
This step is concerned with implementation planning& installation. It deals with material
requirement, processing the material and finally manufactured mechanism is implemented at
actual working site.
Step 6: Monitoring and sign off
The produced products are checked for defects under study also the performance of poka
yoke system is also monitored and project is shut downed.
Fig-4.1Poka-Yoke System design

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4.2 Methods Of Obtaining Poka Yoke
Poka yoke ideas are simple but creative in operation and generation. According to Shingo
"Defects will never be reduced if the workers involved do not modify operating methods when
defects occur."
Following are some of the simple ideas (hints) to avoid mistakes:
1) Using Shapes and Colours
2) Software Warnings and Reminders
3) Using Dialogue Boxes and Software Checks
4) Using Switches and Automatic Braking
5) Using Checklists
6) Visual Prevention Methods
7) Using Lights, Sounds, Signs and Barriers Etc.

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CHAPTER-5
EXAMPLES AND CASE STUDIES OF POKA YOKE
5.1 Examples:
5.1.1 Alarm Systems
They are activated with alarms for security purposes. If an unauthorized person enters the
bank, or the electric circuit of the door bell catches fire, a warning alarm rings, which ensures
that you can take care of the problem before it gets out of hand.
Fig 5.1 Alarm systems
5.1.2 Connector and charger
The figure shows a charger and connector. All the three pins need to fit perfectly within
the three slots provided. This has to be monitored during production. And for that, the design
phase of the product needs to be executed perfectly as well. A slight error in the calculation of
the slot-size or the pin-size can make the device redundant or faulty.

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Fig 5.2: Connector and charger
5.1.3 Fingerprint Identification
This is used extensively in biometrics, forensics, detective agencies, etc. Every
fingerprint in the world is unique, no two are ever the same. The device is such that only the
Fig5.3 : Finger print identification device
fingerprint of that particular person will be required as input. Trying to replicate or use
some one's fingerprint forcibly will not work either.

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5.1.4 Dialysis machine
These machines perform the function of the kidneys and are used for patients suffering
from CKD (Chronic Kidney Disorder). An example of a safety device in this machine is the
efficient design of the air bubble detector. This detector must be fully functional and should
ensure that no air bubble passes to the patient's body. If this occurs, the patient may have seizures
and this can prove fatal. Hence, the detector must be equipped with a proper mechanism to find
out the problem, and give out beeps so that proper action can be taken immediately.
Fig 5.4 Dialysis machine
They are many examples of poka yoke as follows:
 Spindle of CNC machine starts only after closing the safety door. If door is open then machine
will not run. It is shut down poka yoke to avoid accidents.
 The guide pins are used in stamping dies for correct alignment of upper and lower portion. If
there is improper matching assembly of dies will not take place. It is shut down poka yoke.
 If we want to close any file in operating software (e.g. Microsoft Word) it asks for save it or
cancel dialogue box. This is warning system against by mistake closing of file. It is warning
poka yoke.
 To avoid parallax error in reading the measuring instrument small mirror is placed below the
moving pointer. By referring pointer and its mirror image we can take proper reading. It is
warning poka yoke.
 The socket for USB on the computer is designed in such a way that we can’t connect pen drive
or any corresponding pin in opposite or wrong way. It is control poka yoke system.

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5.2 Case studies
Problem: - Job loading in reverse direction causing job rejection, damage to tool and machine
geometry
Aim:- To ensure correct loading of job
Ideas After Brain Storming:-When problem is taken on the table of brainstorming the
following options are obtained for above mentioned problem
 Use of proximity sensor to detect reverse loading of job.
 Use of photo sensor.
 Instructions to operator.
 Separate fixtures to keep the incoming job to enable operator to load the job correctly.
 Painting the correct and wrong end of job with different colors.
 Use of color sensors to differentiate between correct and wrong end of job.
 To provide work rest for the job.
 To provide mechanical stopper. Etc.
From the analysis of various solutions the meeting concludes that they should go with last option
i.e. to provide mechanical stopper.
Fig 5.5 Poka yoke simple practical implementation
Now they will plan for implementing the selected solution and monitor for the result and switch
over to next problem.
Problem Statement:
The problem in this case was missing metal clips. That component which was to be
punch sometimes sent further for punching operation without conforming all metal Clips are
there its place or not. These were results in wastage of time which indirectly affect productivity
of the plant.

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Fig 5.6: Location of metal clips and Punching Location
From chart 1, we can conclude that in each lot of50 components, we found 2 to 3 components
such that metal clips were missed so if we calculate total PPM of the readings, we get that it was
too high which leads to wastage of so much time.
Fig 5.7 : Number of Defects/ 50 Components (6 lots)

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Problem Solution:
There is a very smart solution to this problem which is expressed in circuit diagram
below. The main task we have to do is to stop the air flow from the compressor to pneumatic
cylinder if any one of the metal clip is missing.
Lots No. Of
Samples
Missed
Clips
Components
PPM
(Before)
PPM
(After)
1 50 2 40000 0
2 50 1 20000 0
3 50 0 0 0
4 50 1 20000 0
5 50 4 80000 0
6 50 3 6000 0
Avg 300 11 36666.6 0
TABLE 1:Results after poka yoke method

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Fig 5.8: Result Before and After
From above table and chart we can see the result we obtained after implementation of the Poka
Yoke concept to the punching machine.

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CHAPTER-6
CHALLENGES AND LIMITATIONS OF POKA YOKE
6.1 Challenges of Poka-yoke
As per up till discussion in the paper it seems that poka yoke is one of the best tool in
total quality management but we have to think about the obstacles and challenges against poka
yoke.
Some of challenges are listed below-
 Practical implementation of the mechanism or solution is not possible.
 Process parameters don’t allow changing the existing system.
 Sometimes the poka yoke is not cost effective.
 Interdepartmental relations between production and quality department are not good so each one
think that I don’t have to do anything with that issue.
 Now also we are depending on statistical process control.
 Expert advice is needed for new creative and challenging tasks .It may happen that experts are
not available with small scale industries and expert advice is not economical for their financial
health.
6.2 Characteristics of good poka-yoke devices
Good poka-yoke devices, regardless of their implementation, share many common
characteristics :
 They are simple and cheap. If they are too complicated or expensive, their use will not be cost-
effective.
 They are part of the process, implementing what Shingo calls "100%" inspection.
 They are placed close to where the mistakes occur, providing quick feedback to the workers so
that the mistakes can be corrected.
 Judged by these criteria, the "small dish" solution to the missing-spring problem is an excellent
poka-yoke device:
 It was simple.
 It was cheap, involving only the cost of a small dish.
 It provided immediate feedback about the quality of the work; corrections could be made on the
spot.

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6.3 Qualities of a Good Poka Yoke
A good Poka Yoke must meet the following qualities:
 Early: A good poka yoke must be early in the process, so that it can provide quick feedback --
and help in detecting mistakes the moment they occur.
 Precise: It should be precise, so that it is easy to diagnose and identify what mistake occurred.
 Simple: The poka yoke should be simple -- to develop and maintain. This is quite important
since one doesn’t want to spend time and effort in maintaining poka yokes, and complex poka
yokes will have a fairly high chance of becoming erroneous. Having a buggy poka yoke is worse
than having no poka yoke at all.
 Light: The poka yoke needs to be unobtrusive and transparent. If a poka yoke itself becomes an
overhead to the process, then it will drive the developers/users crazy, and they will find
ingenious ways to avoid it all together. For instance, think about how a developer will feel if
he/she has to run a 70 minute pre-commit script before each and every check-in!

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CHAPTER-7
CONCLUSION
To err is human nature so we can’t blame human being for each and every mistake. As
like err, Intelligence is also human nature so we can dominate preceding nature by next nature.
Poka yoke is just a face of that intelligence. We can avoid the mistakes at the source itself by
using above mentioned methodology. About mistake proofing we can say that it is a system for
organizing work that eliminates any chances of error by new user also. It also allow user to
function without mistake or prevent error that are about to occur. In order to implement quality
management system successfully each activity should aim towards excellence.
Poka yoke is one of the most important tool in TQM(Total Quality Management).
Successful poka yoke results in increased productivity with minimum waste (waste due to
rework, scrap) because we are sure about the quality of product, as mistakes are blocked at
source itself. There may be some practical limitations in poka yoke but we have to overcome all
that for achieving the aim of “Zero Defects, Zero Waste and Zero Delays”. In one sentence poka
yoke is launching preventive actions for systematic movement on the success ladder of
QMS(Quality Management System) with higher level of performance and productivity of system
with high quality products at minimum cost.

Page 25
CHAPTER-8
REFERENCES
1. Anil S. Badiger, R. Gandhinathan, V. N. Gaitonde, Rajesh S. Jangaler “Implementation of
Kaizen and Poka-yoke to Enhance Overall Equipment Performance - A case study”
2. Ivan Fantin (2014). Applied Problem Solving. Method, Application, root causes,
countermeasures, Poka-Yoke and A3. How to make things happen to solve problems.
3. John R. Grout, and Brian T. Downs; “A Brief Tutorial on Mistake-proofing, Poka- Yoke, and
ZQC”; Lean Business Solutions United States
4. John R. Grout, and Brian T. Downs; “A Brief Tutorial on Mistake-proofing, Poka- Yoke, and
ZQC”; Lean Business Solutions United States
5. MrParikshit S. Patil; MrSangappa P. Parit; Mr. Y.N. Burali “Poka Yoke: The Revolutionary Idea
In Total Productive Management”
6. Pratik D. Tak, Shravan S. Wagh “Poka Yoke Implementation On Punching Machine: A Case
Study”
7. Patel Parikshit K, Vidya Nair, Patel Nikunj S “A Review on use of Mistake Proofing (Poka
Yoke) Tool in Blow Molding Process”
8. M. Dudek-Burlikowska, D. Szewieczek “The Poka-Yoke method as an improving quality tool of
operations in the process”
9. Shinto S., Zero Quality Control: Source Inspection and the Poka– Yoke System,

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