The document discusses Poka-Yoka, a Japanese manufacturing technique used to eliminate errors through mistake-proofing. It defines key terms and outlines three simple rules to prevent defects: don't accept a defect, don't make a defect, and don't pass on a defect. The goal of Poka-Yoka is to eliminate errors by designing them out or controlling processes to detect errors before they result in accidents. Examples demonstrate how visual cues, physical constraints, and standardized processes can be implemented to make it difficult or impossible to perform incorrect actions.

1. POKA - YOKA
Lean TOT Program
NPO-Lahore
M Humayun

2. History

3. 3 Rules Need to Remember
Don’t
Accept a
defect
Don’t Make
a defect
Don’t Pass
on a defect
Supplier You Customer
An Error proofing system should take in to consideration three simple rules:
An Error proofing system should take in to consideration three simple rules:

4. The Role of Poka-Yoke
in Human Performance Improvement (HPI)
 You Don’t Know What You, Don’t Know…
 “You just flash that thing, it erases your memory, and you just make
up a new one?”
“The machine shut
down. We must have
made an error!”

5. Definitions
 Human Performance
– ISPI: A series of behaviors executed to accomplish specific results;
very simply, human performance is behavior and results
(HP=B+R)
 HPI
– a disciplined approach to proactively prevent events
triggered by human error
Re + Md ØE
[reducing error AND managing defenses leads to zero events]
 Poka-yoke – Japanese manufacturing tool (Shingo-Toyota)
• POKA - Inadvertent Errors
• YOKERU – Avoid
= Avoid Inadvertent Errors
a.k.a. Mistake-Proofing, Error-Proofing, Fool-proofing (Baka-yoke)

6. Definitions
Event – An undesirable change in the state of structures, systems, or
components or human/organizational conditions (health, behavior, controls,
and so forth) triggered by human error that exceed established significance
criteria.
Defect – any deviation from specifications; nonfulfillment of an intended
requirement or reasonable expectation for use, including safety
considerations often due to human error.

7. Some Guiding Principles
HPI
1. People are fallible and even the best make mistakes.
2. Error-likely situations are predictable, manageable, and preventable!
3. Events can be avoided by understanding the reasons mistakes occur and
applying. the lessons learned from past events.
Poka-yoke
1. Errors are inevitable!
2. Errors can be eliminated!
3. Defects are preventable
- Zero Defects can be achieved!

8. “Substitution”
Substitute “Event”
(or Incident, or Accident, or Injury)
For
“Defect”
(BTW: Mistakes = Errors)

9. Goal of Poka-Yoke
ELIMINATE ERRORS BY:
1. designing the errors out (Design Poka-Yoke)
OR
2. controlling the process at the source to
prevent the error or detect the error before it
becomes an accident (Process Poka-Yoke)

10. Two Types of Process
Poka-Yoke “Devices”
Type I – Eliminate/prevent the error from occurring
at the source. (Prevent Error)
Type II - Detect the error (feedback) in the process of
it occurring, before it results in an accideccident.

11. Level of Poka-Yoka
1)Warning
2)Prevention
3)Elimination

12. Process Poka-Yoke “Devices”
“MAKE IT EASY TO DO IT RIGHT!”
Use “Quick and Easy” Tools by thinking:
C - color, color-coding, checklists…
L – location, lockout…
O – orientation, organization…
P - position, placement, physical…
S - size, shape, sequencing, sensors…

13. Poka Yoka Example

15. Problem
 Workers (especially beginners) sometimes set parts opposite way, which
caused defects.

16. Kaizan Based Solution (Poka Yoka)

17. JIG
Correct
Setting
Mistake
(Possible)
Before
Kaizen
Poka-yoke
Cannot setCorrect
Setting
Disturb Bar
After
Kaizen
Example of Poka-Yoke (1)
Workers (especially beginners) sometimes set parts opposite
way,
which caused defects.

18. Before
Kaizen
After
Kaizen 1
Example of Poka-Yoke (2)
22 products have to be stored into
products box. But workers often
make mistake and put wrong
quantity.
Draw blue line at
22
After Kaizen 2
(True Poka-yoke
Kaizen)
Cut product box at 22
quantities.

19. Before
Kaizen
Example of Poka-Yoke (3)
After
Kaizen
We cannot judge whether the hexagon
head bolt is loosening or not by
appearance.
Match mark
Limit line of
loosened bolt (red)
Match mark
Limit line of
loosened bolt (red)
When bolt is tight
When bolt is loosened,
match mark does not
match.
(Dangerous limit)

20. Before
Kaizen
Example of Poka-Yoke (5)
After
Kaizen
Workers (especially beginners) sometimes assemble wrong
parts,
which caused defect.
Changed these shape one by one.

21. CONCLUSION
The next time you want to be
“S-A-F-E-R”, use a
“Questioning Attitude” to
“Stop, Think and Act” by utilizing
POKA-YOKE…then “Review” the results
Poka-Yoke – The Tool of Choice

23. "They can conquer who believe they can."
- Virgil