Poka yoke is basically making such designs of implements or workplace that the minimizes the chances of mistakes or makes them easily detectable

1. Snigdha Chakraborty
Isha Singh

2.  Poka-yoke (pronounced "POH-kah
YOH-kay") was invented by Shigeo
Shingo in the 1960s.
 The term "poka-yoke" comes from the
Japanese words "poka"
(inadvertent/accidental mistake) and
"yoke" (prevent).
The essential idea of poka-yoke is to design the
process so that mistakes are impossible or at least
easily detected and corrected.

3.  Shigeo Shingo, leading proponent of statistical process
control in Japanese manufacturing realized that defect
would never reduce to zero.
 Some part of the defect will always go untested in
statistical sampling and eventually reach the customer.
 While visiting the Yamada Electric plant in 1961,
Shingo got to know that there was a problem with a
product that had a small switch with two push-buttons
supported by two springs.

4.  Occasionally, the worker assembling the switch would
forget to insert a spring under each push-button.
 Sometimes the error would not be discovered until the
unit reached a customer, and the factory would have
to dispatch an engineer to the customer site to
disassemble the switch, insert the missing spring, and
re-assemble the switch.
 It was costly and company’s credibility was dropping.
 In spite of the Management’s warning the employees
to be attentive and workers’ best efforts, the missing
spring problem would eventually re-appear.

5. Old Approach
• A worker takes 2 springs
out of a large parts box in
his hand and starts
assembling a switch.
• Chances of him forgetting
whether he inserted both
the springs or not is high
New Approach
• A small dish introduced.
• Worker will first takes 2
springs out of the box and
place them on the dish.
• If any spring remains on
the dish, then the worker
knows that he or she has
forgotten to insert it.

7.  Poka-yoke devices fall into two major categories:
1) Prevention or Control Approach - Shuts down the
process when an error occurs. Eg. Microwave
2) Detection or Warning
Approach - Signals the
operator to stop the
process and correct
the problem.
Eg. car beeps if we leave
the key in the ignition

9.  1-10-100 Rule
 The 1-10-100 rule states that as a product or service
moves through the production system, the cost of
correcting an error multiplies by 10.
Activity Cost
Order entered correctly $ 1
Error detected in billing $ 10
Error detected by customer $ 100
“Be more careful” not effective

10. 1. Simple and cheap.
2. Placed close to where the mistakes occur, Quick
feedback 100% of the time.
3. Does not rely on operators catching mistakes.

11. 1. Poor procedures or standards.
2. Machines.
3. Non-conforming material.
4. Worn tooling.
5. Human Mistakes.
 Except for human mistakes these conditions can be
predicted and corrective action can be implemented
to eliminate the cause of defects

12.  There are some kinds of mistake. The causes of
these POKA mostly lead to people.
1. POKA by Carelessness
2. POKA by misunderstanding
3. POKA by brief look
4. POKA by novice ( amateur)
5. POKA by selfishness
6. POKA by dull-witted
7. POKA by irresponsibility
8. POKA by mal function
9. POKA on purpose

14. Inspection Techniques Description
Judgment Assesses quality of production
outputs or
sorts out defects from good
product.
Informative Assesses process by inspecting
outputs and
using information gained to
control the
process (a feedback loop).
Source Assesses beforehand whether the
conditions
necessary for high quality
production to exist.

15. Quality Processes - Design
“Robust” quality processes
to achieve zero defects.
Utilize a Team
Environment- teams
knowledge, experience to
enhance the improvement
efforts.
Elimination of Errors -
Utilize a robust problem
solving methodology to
drive defects towards zero.
Eliminate the
“Root Cause”
of The Errors
Do It Right The First Time -
Utilizing resources to
perform functions correctly
the “first” time.
Eliminate Non-Value Added
Decisions
Implement an Incremental
Continual Improvement
Approach

16.  Poka yoke systems consist of 3 primary methods:
1. Contact
2. Counting
3. Motion-Sequence
 Each method can be used in a control system or a
warning system.
 Each method uses a different process prevention
approach for dealing with irregularities.

17.  These can be as simple as guide pins or blocks that do not allow
parts to be seated in the wrong position prior to processing.
 Contact type helps by physically guiding the manufactured
produce with little or no human intervention to produce goods
that conforms the requirements.
 This method signals to the operator right away that the part is
not in proper position.

18.  The third poka yoke method uses sensors to determine if
a motion or a step in a process has occurred.
 If the step has not occurred or has occurred out of
sequence, the sensor signals a timer or other device to
stop the machine and signal the operator.

19.  Used when a fixed number of operations are
required within a process or when a product has a
fixed number of parts that are attached to it.
 A sensor counts the number of times a part is used
or a process is completed and releases the part only
when the right count is reached.

23.  Error-proofing is a manufacturing technique of
preventing errors by designing the manufacturing
process, equipment, and tools so that an operation
literally cannot be performed incorrectly (CAD &
CAM, CNC sewing machine for on-line monitoring
of seam quality).
 Some examples have been given from the apparel
sector.

24. Example -1

25. Example -2

26.  The bobbin needs to be fitted in the hook set in the
right way for the thread to be taken up by the feed
mechanism.
 This is done by simple poka yoke of providing a
groove in the ‘hook set’ where the bobbin hook will
fit in with a clicking sound.
Example -3

27.  The automatic button feed mechanism uses contact
type of poka yoke for sorting of the buttons before
positioning them to be stitched correctly on the
garment.
Example -4

28.  Don’t wait for the perfect POKA YOKE. Do it now!
 If your POKA YOKE idea has better than 50% chance
to succeed…Do it!
 Do it now….improve later!

29.  “Using Poka-Yoke Techniques for Early Defect
Detection” by Harry Robinson
 Mistake Proofing (Poka Yoke and Error Proofing)
 “Poka-yoke-improving-product-quality-
preventing-defects” (Book)
 http://www.slideshare.net/PrateekBapna/5s-
kaizen-pokayoke

30. Thank You!