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MISTAKE-PROOFING
(POKA-YOKE)
The Effective Approach to Zero Defects
© Operational Excellence Consulting. All rights reserv...
© Operational Excellence Consulting
LEARNING OBJECTIVES
2
Gain knowledge on
the key concepts and
principles of Zero
Qualit...
© Operational Excellence Consulting
CONTENTS
3
INTRODUCTION TO
ZERO QUALITY
CONTROL
BASIC ELEMENTS
OF THE ZQC
SYSTEM
USING...
© Operational Excellence Consulting
TRADITIONAL INSPECTION IS A POOR SUBSTITUTE FOR QUALITY
4
Traditional 100% inspection ...
© Operational Excellence Consulting
WHAT IS ZERO QUALITY CONTROL (ZQC)?
5
The Goal is
Zero Defect
Defects Can Be
Prevented...
© Operational Excellence Consulting
WHY FOCUS ON ZERO DEFECTS?
6
Improve company
image and reputation
Facilitate lean
prod...
© Operational Excellence Consulting 7
WHAT CAUSES DEFECTS?
Damaged or
excessively variable
materials
Worn machine parts Si...
© Operational Excellence Consulting
THE ZQC APPROACH CONSISTS OF FOUR BASIC ELEMENTS
8
Source
inspection
100 percent
inspe...
© Operational Excellence Consulting
● Source inspection is the key to the ZQC
control function
● Source inspection assures...
© Operational Excellence Consulting
1. Judgment inspection:
Inspection that discovers
defects
2. Informative inspection:
I...
© Operational Excellence Consulting
SOURCE INSPECTIONS PREVENT DEFECTS
11
● Source inspection is different from
judgment i...
© Operational Excellence Consulting
SOURCE INSPECTION KEEPS ERRORS FROM TURNING INTO DEFECTS
12
The integration of Check a...
© Operational Excellence Consulting
© Operational Excellence Consulting. All rights reserved.
100 PERCENT INSPECTION CATCH...
© Operational Excellence Consulting
“
Humans are animals that
make mistakes.”
SHIGEO SHINGO
14
© Operational Excellence Consulting
WHAT IS POKA-YOKE?
15
Poka-yoke means implementing simple low-cost devices that
either...
© Operational Excellence Consulting
Poka-yoke should not be implemented
for the sake of trying to look Lean!
POKA-YOKE IS ...
© Operational Excellence Consulting
TWO APPROACHES TO POKA-YOKE
17
CONTROL SYSTEM
● Controls the process so that when a
de...
© Operational Excellence Consulting
● People and machines do make
mistakes or errors
● A portion of mistakes turn into
def...
© Operational Excellence Consulting
● An example of a positive stop based
on the contact method is on
equipment that requi...
© Operational Excellence Consulting
● When fast-food restaurant employees
are filling a bag of fries, customers will
be un...
© Operational Excellence Consulting
● A common poka-yoke system in
assembly processes is light-guided
picking, also known ...
© Operational Excellence Consulting
● Mistakes can be prevented by
separating contradictory or opposing
feature requiremen...
© Operational Excellence Consulting
● At the pharmacy, the more
complicated your routine
medications are, the harder they
...
© Operational Excellence Consulting
BEST PRACTICES
24
● Poka-yoke is a means to achieve
the goal of zero defects, not the
...
© Operational Excellence Consulting
Operational Excellence Consulting is a management
training and consulting firm that as...
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Mistake-Proofing (Poka-Yoke)

The Zero Quality Control (ZQC) is the most effective mistake-proofing approach. The system prevents defects as well as monitors processing conditions at the source and corrects errors that would cause defects.

Based on the breakthrough approach developed by Dr. Shigeo Shingo, mistake-proofing devices called poka-yoke are used to check and give feedback about each product or operation in the process, not just a sample.

This presentation introduces the basic methodology of ZQC in a logical format and covers all aspects of this important manufacturing improvement strategy. You will learn that the culture of zero defects can be developed by training and educating teams on the approaches to poka-yoke, and using contact and non-contact methods with visual controls and auditory systems to create effective, reliable and low-cost poka-yoke systems that catch mistakes and prevent defects from happening.

LEARNING OBJECTIVES

1. Gain knowledge on the key concepts and principles of Zero Quality Control
2. Learn the approaches, methods and tools for designing and implementing poka-yoke systems
3. Identify the limitations and best practices of mistake-proofing

CONTENTS

1. Introduction to Zero Quality Control
2. Basic Elements of the ZQC System
3. Using Poka-yoke Systems
4. Examples of Poka-yoke Applications
5. Limitations & Best Practices

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Mistake-Proofing (Poka-Yoke)

  1. 1. MISTAKE-PROOFING (POKA-YOKE) The Effective Approach to Zero Defects © Operational Excellence Consulting. All rights reserved.
  2. 2. © Operational Excellence Consulting LEARNING OBJECTIVES 2 Gain knowledge on the key concepts and principles of Zero Quality Control Identify the limitations and best practices of mistake-proofing Learn the approaches, methods and tools for designing and implementing poka- yoke systems NOTE: This is a PARTIAL PREVIEW. To download the complete presentation, please visit: https://www.oeconsulting.com.sg
  3. 3. © Operational Excellence Consulting CONTENTS 3 INTRODUCTION TO ZERO QUALITY CONTROL BASIC ELEMENTS OF THE ZQC SYSTEM USING POKA-YOKE SYSTEMS EXAMPLES OF POKA-YOKE APPLICATIONS 01 04 03 02 LIMITATIONS & BEST PRACTICES 05
  4. 4. © Operational Excellence Consulting TRADITIONAL INSPECTION IS A POOR SUBSTITUTE FOR QUALITY 4 Traditional 100% inspection does not provide 100% defect-free products.
  5. 5. © Operational Excellence Consulting WHAT IS ZERO QUALITY CONTROL (ZQC)? 5 The Goal is Zero Defect Defects Can Be Prevented Does Not Place Blame on People ZQC is an approach that does not point fingers at people. It recognizes that machines and people make mistakes sometimes, and it finds ways to keep those errors from turning into defects. Zero Quality Control (ZQC) is an approach for achieving zero defects. “Zero” refers to the goal of making products with zero defects. ZQC is based on the principle that defects are prevented by controlling the performance of a process so that it cannot produce defects – even when a mistake is made by a person or machine.
  6. 6. © Operational Excellence Consulting WHY FOCUS ON ZERO DEFECTS? 6 Improve company image and reputation Facilitate lean production methods with smaller inventories Improve productivity and competitiveness Develop a culture of continuous improvement and innovation Maintain customer satisfaction and loyalty High cost of poor quality (e.g. rework, scrap, warranty claims)
  7. 7. © Operational Excellence Consulting 7 WHAT CAUSES DEFECTS? Damaged or excessively variable materials Worn machine parts Simple human mistakes Specification of inappropriate procedures or standards Excessive variability in the operations Most defects happen in one of five situations:
  8. 8. © Operational Excellence Consulting THE ZQC APPROACH CONSISTS OF FOUR BASIC ELEMENTS 8 Source inspection 100 percent inspection A short Feedback loop Mistake-proofing (poka-yoke) systems FOUR ELEMENTS OF ZQC
  9. 9. © Operational Excellence Consulting ● Source inspection is the key to the ZQC control function ● Source inspection assures that the conditions are in place beforehand to perform a process properly ● Source inspection is different from other types of inspection, such as judgement inspection or informative inspection SOURCE INSPECTION © Operational Excellence Consulting. All rights reserved. 9
  10. 10. © Operational Excellence Consulting 1. Judgment inspection: Inspection that discovers defects 2. Informative inspection: Inspection that reduces defects 3. Source inspection: Inspection that eliminates defects THREE APPROACHES TO PRODUCT INSPECTION AND THEIR RESULTS 10 Source Inspection Informative Inspection Judgment Inspection Discovers defects but does not reduce them Reduces defects by informing the process after they happen Eliminates defects by catching and fixing their causes
  11. 11. © Operational Excellence Consulting SOURCE INSPECTIONS PREVENT DEFECTS 11 ● Source inspection is different from judgment inspection and informative inspection ● Source inspection catches errors – and gives feedback about them – before processing ● This is the integration of the Check and Do stages: something controls the doing so that it cannot be done wrong A Process with Zero Defects Discovery of mistakes before processing Feedback and corrective action
  12. 12. © Operational Excellence Consulting SOURCE INSPECTION KEEPS ERRORS FROM TURNING INTO DEFECTS 12 The integration of Check and Do stages keeps defects from being passed down the line.
  13. 13. © Operational Excellence Consulting © Operational Excellence Consulting. All rights reserved. 100 PERCENT INSPECTION CATCHES ALL ERRORS ● The second unique element of the ZQC system is that it does a source inspection on every single product ● An SQC system, however, only inspects a sampling of the product and does not prevent defects from occurring ● ZQC uses methods that check 100% of the products 13
  14. 14. © Operational Excellence Consulting “ Humans are animals that make mistakes.” SHIGEO SHINGO 14
  15. 15. © Operational Excellence Consulting WHAT IS POKA-YOKE? 15 Poka-yoke means implementing simple low-cost devices that either detect abnormal situations before they occur, or once they occur, stop the line to prevent defects. POKA Mistakes YOKE Prevention Source: Based on Pascal Dennis, 2015
  16. 16. © Operational Excellence Consulting Poka-yoke should not be implemented for the sake of trying to look Lean! POKA-YOKE IS WORTH PURSUING ONLY WHEN HUMAN ERROR IS THE MAIN CAUSE OF QUALITY DEFECTS 16
  17. 17. © Operational Excellence Consulting TWO APPROACHES TO POKA-YOKE 17 CONTROL SYSTEM ● Controls the process so that when a defect occurs, the process stops until correction takes place ● High capability of achieving zero defects ● For example, an ATM machine withholds your cash until you have removed your card so that you cannot forget the card ● Signals operators when a defect occurs so that operators take corrective action ● Sometimes an automatic shutdown is not an option ● For example, when word-processing software highlights a misspelled word so that you can go back and fix it WARNING SYSTEM
  18. 18. © Operational Excellence Consulting ● People and machines do make mistakes or errors ● A portion of mistakes turn into defects ● Poka-yoke systems can be applied to prevent mistakes from happening, as well as detect mistakes after they have happened THE DUAL FOCUS OF POKA-YOKE SYSTEMS – MISTAKE PREVENTION & MISTAKE DETECTION Defects Mistakes Process PREVENTION Poka-yoke that focuses here works on mistake prevention or making mistakes impossible. DETECTION Poka-yoke that focuses here works on mistake detection, or making sure mistakes do not turn into defects. 18
  19. 19. © Operational Excellence Consulting ● An example of a positive stop based on the contact method is on equipment that requires operators to perform a safety task before starting the machinery. To activate the power to the equipment, the operator must first close the cover. Other examples include blenders, washers and microwaves that stop when their door is opened to prevent operator injury or damage to the equipment. SAFETY COVER 19
  20. 20. © Operational Excellence Consulting ● When fast-food restaurant employees are filling a bag of fries, customers will be unhappy if the bag is too little, but if it is too much, the company loses money. With a dispenser such as the french-fry scooper, the amount of fries can be controlled. Based on the fixed- value method, this tool ensures that bags of fries are slightly overflowing without being too generous. DISPENSING EQUIPMENT 20
  21. 21. © Operational Excellence Consulting ● A common poka-yoke system in assembly processes is light-guided picking, also known as pick-to-light. Pick- to-light devices use colored LEDs to visually guide assemblers to pick the correct parts, in the right quantities, and in the proper sequence. This motion- step method reduces the risk of human errors and speeds up build times to ensure high quality while maximizing productivity. PICK-TO-LIGHT 21
  22. 22. © Operational Excellence Consulting ● Mistakes can be prevented by separating contradictory or opposing feature requirements in time. The light indicates the allowed flow of traffic separating the flow by specific periods of time. Based on the motion-step method, many stoplights are timed with a three- second delay to allow previous cars to exit the intersection before cross traffic is permitted to enter. TIME SEPARATION 22
  23. 23. © Operational Excellence Consulting ● At the pharmacy, the more complicated your routine medications are, the harder they can be to administer properly. In this case, having a visual indicator of whether you’ve taken your pills for Wednesday can do a great deal to make sure that you’re getting the medicine that you need at the right time. PHARMACY 23
  24. 24. © Operational Excellence Consulting BEST PRACTICES 24 ● Poka-yoke is a means to achieve the goal of zero defects, not the end in itself ● Do not react to human errors by blaming them for being sloppy ● Line process capability issues should be addressed first before implementing poka-yoke ● Poka-yoke should make the job of the operator easier, not add more work ● Involve team members in the design and implementation of poka-yoke systems ● Provide knowledge such as used cases to the team members in implementing poke-yoke ● Do not make poka-yoke devices extremely sophisticated and complicated – go for the simplest and most effective method!
  25. 25. © Operational Excellence Consulting Operational Excellence Consulting is a management training and consulting firm that assists organizations in improving business performance and effectiveness. Based in Singapore, the firm’s mission is to create business value for organizations through innovative design and operational excellence management training and consulting solutions. For more information, please visit www.oeconsulting.com.sg END OF PARTIAL PREVIEW

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