The document discusses the concept of poka-yoke or mistake-proofing. It begins with an introduction that defines poka-yoke as a mechanism that prevents mistakes from being made and is obvious at a glance. The document then covers classifications of poka-yoke devices by Dr. Shigeo Shingo, the differences between Zero Quality Control (ZQC) and Statistical Process Control (SPC), examples of everyday poka-yoke devices like stoves and microwaves, and characteristics of good poka-yoke solutions like being simple and providing quick feedback. It concludes by emphasizing the importance of thinking simply, specifically, and responsively when developing poka-yoke mechanisms.

1. POKA­YOKE
RAKESH AMBRE – 04319401
L. SUNDARAVALLI – 04419801
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2. Presentation plan
 Introduction
 What is Mistake Proofing?
 Classifications by Dr. Shigeo Shingo
 ZQC Vs. SPC
 Case report – Push buttons
 Classifications of Poka­yoke devices
 Everyday Examples
 Characteristics of good Poka­yoke
devices
 Poka­yoke in software
 Conclusions
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3. Introduction
 Pronounced as POH­kah YOH­kay
 Poka­yoke is the Japanese word for mistake­
proofing
 Discrimination between mistakes and defects
 Mechanism that prevents a mistake from being
made which is obvious at a glance.
 Examples: Push buttons
Welding nuts into panels
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4. TO ERR IS HUMAN NATURE
BUT
INTELLIGENCE IS ALSO HUMAN
NATURE
SO
NEVER STOP ,FINDING WAYS OF
NOT MAKING MISTAKES
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5. POKA YOKE (Mistake Proofing)
CAUSES EFFECTS
• DEFECTS
• DISTRACTION
(QUALITY)
• CONFUSION • INSUFFICIENT
INATTENTION
ERROR NUMBER
• LACK OF (QUANTITY)
PRACTICE
• ACCIDENTS
• UNCERTAINTY (SAFETY)
• WORK DELAY
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6. No System of Barriers is Perfect…
Error
Harm
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Adapted from James Reason’s
Managing the Risk of Organizational Accidents

7. No System of Barriers is Perfect…
…But improvements can be made
Error Error
Harm Harm
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Adapted from James Reason’s
Managing the Ris of Organizational Accidents

8. WHAT IS MISTAKE PROOFING
A SYSTEM For Organizing Work that
 Excludes any risk of error even by the
beginner
 Allows everyone to operate without mistake
 Prevents error that are about to occur
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9. Classifications by Dr. Shigeo Shingo
 Judgment inspection
 Inspection in quality
 Informative inspection
 Uses data gained from inspection to control
the process and prevent defects. Examples:
Traditional SPC and repeated checks and self­
checks in ZQC
 Source inspection
 Before the fact at source, before reaching
customer or Forcing function
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10. ZQC Vs. SPC
 "...a look at SPC methods as they are
actually applied shows that feedback and
corrective action ­ the crucial aspects of
informative inspections ­ are too slow to be
fully effective."
 PokaYoke techniques to correct mistakes +
Source inspection to prevent mistakes =
ZQC
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11. Continued…
 ZQC is not as effective as SPC for defects
that result from variance in measurement data
 ZQC is a special case of SPC for defects that
result from variance in attribute data.
 ZQC's source inspection can be used effectively
to eliminate mistakes and in conjunction with SPC
to eliminate the recurrence of special causes.
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12. Case Report – Push buttons
 In the old method, a worker began by taking two
springs out of a large parts box and then
assembled a switch.
 In the new approach, a small dish is placed in
front of the parts box and the worker's first task is
to take two springs out of the box and place them
on the dish. Then the worker assembles the
switch. If any spring remains on the dish, then the
worker knows that he or she has forgotten to
insert it.
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13. PokaYoke devices
 A prevention device engineers the process
so that it is impossible to make a mistake
at all.
 A 3.5 inch computer diskette
 A detection device signals the user when a
mistake has been made, so that the user
can quickly correct the problem
 Small dish for push buttons
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14. Everyday Examples
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15. Which dial turns on the burner?
Stove A
Stove B

16. Other examples
 Prevention devices
 Microwaves
 Washing machines
 Central locking in modern cars
 Key locks in mobiles
 Detection devices
 Refrigerators
 Messaging in most soft wares
 Beeps in automobiles if key is left in ignition
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17. Characteristics of PokaYoke
devices
 Simple and cheap
 Part of the process, permitting 100% inspection
 Placed close to where the mistakes occur,
providing quick feedback.
 Designed to stop a particular mistake
 A detection device cannot provide a complete
error proof solution
 Necessary and not a sufficient solution
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18. Common Mistake­proofing Devices
 Guide Pins
 Blinking lights and alarms
 Limit switches
 Proximity switches
 Counters
 Checklists
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19. PokaYoke in software
 Prevention devices
 Development of programming languages
 Detection devices
 Software testing
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20. Conclusions:
 Think simple
 Think specific
 Think attributes
 Think early
 Think responsive
 Think re­use
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21. THANK YOU
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