International Journal of Science and Research (IJSR), India Online ISSN: 2319-7064
Volume 2 Issue 2, February 2013
www.ijsr.net
A Review on use of Mistake Proofing (Poka Yoke)
Tool in Blow Molding Process
Patel Parikshit K
1
, Vidya Nair
2
, Patel Nikunj S
3
1
LDRP Institute of Technology and Research,
Near KH 5 Circle, Sector 15, Gandhinagar -382015, Gujarat, India
2
LDRP Institute of technology and research,
Near KH 5 Circle, Sector 15, Gandhinagar -382015, Gujarat, India
3
LDRP Institute of technology and research,
Near KH 5 Circle, Sector 15, Gandhinagar -382015, Gujarat, India
Abstract:
Manufacturing defects or errors are always the key concerns of any manufacturing industry. The success of any
organization depends on the quality of product especially right product produced. This dissertation work is to be done in small blow
moulding company, which manufactures the Air duct for automobile air conditioners. The initial research shows the past trends of
rejection is between 8-9% which includes human error in material removal, wrong fitting of clamp, molding defects, etc. the need is to
reduce that to compete in highest competitive market and to continuous satisfaction of customer. One of the successful devices in lean
production to eliminate waste caused by errors is ‘mistake-proofing’ or ‘Poka-yoke’. Mistake-proofing is one of the effective approaches
that prevents inadvertent errors and helps workers to be mistake-proof and does not allow defective products to flow to next processes.
The Poka-Yoke approach was developed in the manufacturing industry as a way of improving productivity by reducing errors using
often very simple adaptations. This dissertation work corroborates that, as Poka-Yokes to be implemented in manufacturing process of
Air duct – Blow molding process. Methodology/approach: This dissertation work demonstrate the use of the Poka-Yoke approach in a
manufacturing process of blow molding process, highlighting how they served to improve product quality by reducing rejection/waste.
Status: the relevant literature review has been done along with study of Poka Yoke technique. Next step of study of manufacturing
process of Air duct by blow molding is done and process mapping is done through process flow diagram. Next Phase of Work:
Identification of the processes which contributes to the rejection and rework after process study. Application of Poka Yoke in the
manufacturing process mainly to eliminate manual error by designing suitable means which reduces the rejection.
Keywords: poka-yoke, blow moulding process, air duct, mistake proofing.
1. Introduction
In the recent years intensifying competition in the
international economy caused a major change in approach to
quality management. The quality action should therefore
include its reach the whole product life cycle, starting from
customer identification requirements and expectations, by
the customer’s service. An important factor in the
functioning of company shall take appropriate selection
constant improvement strategies of processes, where special
emphasis is put on preventing strategy. The prevention
strategy replaced detection strategy; new strategy indicates
shifting the focus on the functions and activities relating to
improving each element and operation broader process. In
the present time we have techniques, tools and methods
which support such approach to the quality. Thanks to their
implementation in the organization following minimizing
costs, eliminate defects and thus more monitoring and
improving the quality operations in processes.
Based on defect prevention is analysis and monitoring of
each activity in the process and implementation at each stage
of the process and each step operations tests and safeguards
protecting against appearance of a problem. Collection of
information on emerging deficiencies and prevent them is a
much more efficient way of improving quality than the
standard quality control. Observations of the current
problems arising in processes can be their causes
demonstrate.
It is therefore an effective approach to apply mechanisms to
prevent errors formation precisely at the moment they occur.
Idea of "grounds command defects" known as the method or
technique Poka-Yoke is just such mechanism. Poka-Yoke
method was introduced by Shigeo Shingo in 1961, when this
was one of engineers Toyota Motor Corporation. This
method, in other words, is to prevent defects and errors
originating in the mistake. 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
The main objective of the project is to produce the defect
free product, i.e. improving product and process quality of
blow moulded product by implementing preventive tool –
Poka Yoke.
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International Journal of Science and Research (IJSR), India Online ISSN: 2319-7064
Volume 2 Issue 2, February 2013
www.ijsr.net
2. Problem
Manufacturing of Air duct is done through blow moulding
technology. After blow moulding process, it requires to
remove excess material. Currently, Material removal process
is done manually. Workers remove the excess material with
sharp knife.
Removal process is totally depends on workers skill, there
are high chances of improper removal of material which
rejects material. Past rejection data is also very high due to
manual removal (Human Error). Below figure shows the
specific area and problem.
Figure 1: Defects in Air duct
The problem requires to be attended with high priority and it
is very important to reduce rejection because it affects
company’s reputation and cost as well. The human error
elimination is required in such a way that it eliminates the
error. For that purpose, Poka Yoke techniques is identified
and it will be implemented in manufacturing process, i.e.
improvement in manufacturing process so the said problem
can be eliminated.
3. Relevant Research Review
M. Dudek-Burlikowska and D. Szewieczek has investigated
the Poka-Yoke method as an improving quality tool of
operations in the process. The Purpose of research is to a
new approach for the implementation of quality philosophy
Zero Quality Defects with usage of the Poka-Yoke method
in the polish organization has been presented. The possibility
of usage of mistake proofing device is connected with
monitoring and improvement of operations in the process.
The finding of the research is, at the present time the
organizations should implement quality tools, techniques,
methods which support the prevention strategy and should
pay attention to improving each element and operations in
the process. The Poka-Yoke method of preventing errors by
putting limits on how operation can be performed in order to
force the correct completion of the operation has been
presented. The possibility of implementing of the Poka-Yoke
method as a factor of improving operation in the process in
the motorizations companies has been shown.
Tarcisio Abreu Saurin, José Luis Duarte Ribeiro and Gabriel
Vidor have conducted research on A framework for
assessing poka-yoke devices. This study introduces a
framework for assessing poka-yoke devices (PD),
encompassing both those designed for quality control
(referred to as quality PD) and those designed to control
hazards to health and safety at work (referred to as safety
PD). The framework assesses the processes of the design,
operation and maintenance of PD, rather than the outcomes
of these processes. The development of the framework
involved three stages: (a) defining 15 attributes of PD,
identifying those that provide fail-safe characteristics and
those that inform best practices in design, implementation
and maintenance; (b) defining what the set of evidence and
what the sources of evidence should be for assessing the
existence of each attribute; the sources include documents,
interviews, observations and a meeting to discuss the results
of the assessment with company representatives; and (c)
defining a scoring system to express the results of the
assessment. The application of the framework is illustrated
by means of assessing four PD; two of them being concerned
with quality and two with safety.
Cristóbal Miralles, Raymond Holt, Juan A. Marin-Garcia
and Lourdes Canos-Daros have conducted case study to
design of workplaces through the use of PokaYoke. Purpose:
Employment plays an important part in many people’s lives
beyond merely providing income, since continued
participation in work can have many therapeutic benefits for
workers defined as disabled. However, disabled workers
face a range of barriers to employment, despite legislation
intended to improve workplace accessibility emphasizing
adaptations to the workplace, which many employers often
find difficult and expensive.
The Poka-Yoke approach was developed in the
manufacturing industry as a way of improving productivity
by reducing errors using often very simple adaptations. This
paper argues that, as Poka-Yokes are designed to make life
easier and improve the performance of workers without
impairments, they are closer to the philosophy of Universal
Design than to Accessible Design, and offer an easy and
inclusive way of making work more accessible for all kind
of workers.
Design/methodology/approach: This paper provides a case
study demonstrating the use of the Poka-Yoke approach in a
sheltered work centre for disabled; highlighting how they
served to improve accessibility to work by fulfilling
Universal Design principles.
Findings: Our research allows us to demonstrate the great
potential of Poka-yokes for gaining accessibility to the
workplace. The real application of this approach, both in
sheltered work centers and ordinary companies, can
contribute to improve the high unemployment rates of
disabled people.
Research limitations/implications: The proposal is innovative
and was applied in one specific company. Thus, a range of
customized Poka-yokes would be desirable for different
industrial sectors.
Practical implications: Managers of sheltered work centers,
and also of ordinary companies, can realize about the great
potential of Poka-Yokes as an easy means of gaining
flexibility and accessibility.
Arash Shahin and Maryam Ghasemaghaee have investigated
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International Journal of Science and Research (IJSR), India Online ISSN: 2319-7064
Volume 2 Issue 2, February 2013
www.ijsr.net
use and implication of Poka Yoke technique in Service
sector. Comparing with other sectors, although the service
sector has been growing fast and shares most of the revenue
and employment worldwide; apparently its productivity and
quality have not been growing. What is vital in today’s
growing of the service sector is to have a better
understanding of tools, techniques, and policies to help keep
management’s focus on productivity and quality
improvement. The rigorous application to the service sector
of those engineering and management techniques that have
been so effective in the manufacturing sector is a starting
point for service managers to help them bring their
companies back to life. In this paper, Poka yoke as one of
the effective quality design techniques experienced in
manufacturing has been suggested and developed for service
fail-safing. For this purpose, the subjects of service failure
and service recovery have been introduced. Then, service
Poka yoke has been demonstrated and its solutions have
been classified. Some case examples have been presented in
three categories as layout, technology and self-service for a
better understanding of the subject. This paper also has
proposed a framework, by which the common and
uncommon elements of service Poka yoke and Service
recovery solutions have been classified and addressed
schematically. The framework seems very helpful for the
managers to focus on the more effective approaches, if they
are about to fix problems at the design stage of the
processes. Finally, some barriers and critical success factors
of adopting Poka yoke in services applications has been
discussed.
Ramin Sadri, Pouya Taheri, Pejman Azarsa and Hedayat
Ghavam have carried out research to improve the
productivity through Mistake-proofing of Construction
Processes. Construction defects are always the key concern
of the construction industry. Different constructed facilities
generate different types of defects and demand different
levels and types of quality, depending on the functions,
system types, and materials used.
To achieve mistake-proofing concept in a construction site,
zones where are prone to error should be identified. These
mistakes could be quality problems, delay in delivering a
mid-process product, safety issues and so on. By tracking
where the problems locate, the project manager could place
his/her attention on investigating and resolving the problem,
and implement the mistake-proofing device to prevent
recurrence of problems in the future. There are six of main
mistake-proofing principles listed in order of preference in
fundamentally addressing mistakes: (1) Elimination seeks to
eliminate the possibility of error by redesigning the product
or process so that the task or part is no longer necessary; (2)
Replacement substitutes a more reliable process to improve
consistency; (3) Prevention engineers the product or
processes so it is impossible to make a mistake at all; (4)
Facilitation employs techniques and combining steps to
make work easier to perform; (5) Detection involves
identifying an error before further processing occurs so that
the user can quickly correct the problem; (6) Mitigation
seeks to minimize the effect of errors. The results show that
the construction operations have high potential of mistake-
proofing, and therefore the application of Poka-yoke devices
can finally lead to drastic promotion in construction industry.
At last section, a case study related to the simple operation of
a trolley hoist also conducted to evaluate productivity
improvement due to the process mistake proofing in practice
4. Poke Yoke
Poka-yoke is a Japanese term that means "fail-safing" or
"mistake-proofing". A poka-yoke is any mechanism in a lean
manufacturing process that helps an equipment operator
avoid (yokeru) mistakes (poka). Its purpose is to eliminate
product defects by preventing, correcting, or drawing
attention to human errors as they occur. The concept was
formalised, and the term adopted, by Shigeo Shingo as part
of the Toyota Production System. It was originally described
as baka-yoke, but as this means "fool-proofing" (or "idiot-
proofing") the name was changed to the milder poka-yoke.
Figure 2: Simple Example of Poka Yoke
Shigeo Shingo recognized three types of poka-yoke for
detecting and preventing errors in a mass production system.
The contact method identifies product defects by testing the
product's shape, size, color, or other physical attributes. The
fixed-value (or constant number) method alerts the operator
if a certain number of movements are not made. The motion-
step (or sequence) method determines whether the prescribed
steps of the process have been followed.
Either the operator is alerted when a mistake is about to be
made, or the poka-yoke device actually prevents the mistake
from being made. In Shingo's lexicon, the former
implementation would be called a warning poka-yoke, while
the latter would be referred to as a control poka-yoke. Shingo
argued that errors are inevitable in any manufacturing
process, but that if appropriate poka-yokes are implemented,
then mistakes can be caught quickly and prevented from
resulting in defects. By eliminating defects at the source, the
cost of mistakes within a company is reduced.
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
mistakes resulting from the defect is yet one, the potential
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International Journal of Science and Research (IJSR), India Online ISSN: 2319-7064
Volume 2 Issue 2, February 2013
www.ijsr.net
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 following
assumptions:
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),
At the earliest as soon as possible signal error before it
become the defect (in the inspection of information is
amended to self-control 'upwards' means checking prior
operations and material obtained),
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. The technique starts by analyzing the
process for potential problems, identifying parts by the
characteristics of dimension, shape, and weight, detecting
process deviation from nominal procedures and norms.
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 of 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.
6. How to use it?
Step by step process in applying poka-yoke:
Identify the operation or process - based on a pareto.
Analyze the 5-whys and understand the ways a process
can fail.
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)
poka-yoke take a more comprehensive approach instead
of merely thinking of Poka-yokes as limit switches, or
automatic shutoffs a poka-yoke can be electrical,
mechanical, procedural, visual, human or any other form
that prevents incorrect execution of a process step
Determine whether a contact - use of shape, size or other
physical attributes for detection, constant number - error
triggered if a certain number of actions are not made
sequence method - use of a checklist to ensure
completing all process steps is appropriate
Trial the method and see if it works
Train the operator, review performance and measure
success.
7. Poka Yoke Visual Examples
1. Diskette
Figure 3: Diskette
3.5 inch diskette cannot be inserted unless diskette is oriented
correctly. This is as far as a disk can be inserted upside-
down. The beveled corner of the diskette pushes a stop in the
disk drive out of the way allowing the diskette to be inserted.
This feature, along with the fact that the diskette is not
square, avoids incorrect orientation.
2. Pen
This pen prevents ruining shirts by retracting the tip
automatically when the pen is clipped into your shirt pocket.
The catch that keeps the tip out is actually in the pocket clip.
When you pullout on the clip to put it on your shirt, the pin
that engages the catch is released causing the tip to retract
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International Journal of Science and Research (IJSR), India Online ISSN: 2319-7064
Volume 2 Issue 2, February 2013
www.ijsr.net
Figure 4: Pen
3. Fueling Cap of Automobile
Fueling area of car has three mistake-proofing devices:
Filling pipe insert keeps larger, leaded-fuel nozzle from
being inserted
Gas cap tether does not allow the motorist to drive off
without the cap
Gas cap is fitted with ratchet to signal proper tightness and
prevent over-tightening.
Figure 4: Fueling area of Car
8. Methodology
The goal of manufacturing is to produce value-added
products in a timely manner, which is free of defects. Poke
Yoke is applied in fundamental areas. The main objective of
Poka Yoke is to achieve zero defects. It is used to create a
system that prevents defects from occurring, and it used as a
system to catch defects, which have just occurred and
prevent them from continuing through the system.
Step by step process in applying poka-yoke:
1. Study and Analyze the operation or process Manufacturing
process
2. Analyze and understand the ways 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) poka-yoke
4. Implement the poka yoke – modify process
5. Trial the method and see if it works
6. Result and conclusion
9. Acknowledgement
Authors of this paper thankfully acknowledge the generous
and continuous support of Delta blow pack industries.
References
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Hedayat Ghavam - Improving Productivity through
Mistake-proofing of Construction Processes in 2011
International Conference on Intelligent Building and
Management, Proc .of CSIT vol.5 (2011) IACSIT
Press, Singapore
[2] Lionel Naudé - The Wider Application of Poka Yokes
(Mistake Proofing) in the Mining Industry in
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Yoke method as an improving quality tool of
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[4] Arash Shahin, Maryam Ghasemaghaee - Service Poka
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[5] Cristóbal Miralles, Raymond Holt, Juan A. Marin-
Garcia, Lourdes Canos-Daros - Universal design of
workplaces through the use of Poka-Yokes: Case study
and implications in JIEM, 2011 – 4(3):436-452 –
Online ISSN: 2013-0953 – Print ISSN: 2013-8423
[6] Zero Quality Control: Source Inspection and the Poka-
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[9] V. Feigenbaum, Total Quality Control: Engineering and
Management, 3rd ed. New York: McGraw Hill, 1983.
Author Profile
Patel parikshit received the diploma degree in
electrical engineering in 2006, B.E degree in
Automobile Engineering in 2011.
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