2. Table of Contents
Session 1
Paradigm Shift For Zero Errors
Session 2
Introduction of Poka-Yoke
Session 3
Process Waste Management
Session 4
Zero Defect Quality (ZDQ)
Session 5
3 Qualifiers of Poka-Yoke
How to Poka-Yoke?
Session 6
Poka-Yoke Examples From Daily Life
Session 7
Poka-Yoke Systems
Session 8
Method of Poka-Yoke
Session 9
Types of Poka-Yoke
Session 10
Principles of Poka-Yoke
Session 11
100-1000-10000 Rule
Session 12
Types of Human Mistakes
2
4. Paradigm Shift For Zero Error
Shift in Paradigm
SEE
Satisfied
Customer
Do “Poka Yoke”
Principles
DO
GET
Improved
Quality
Reduction in
defects/rejects
Dr. Albert Einstein said:
“The significant problems we face cannot be solved by the same level of thinking
that created them”
7
5. Managing through Kaizen Paradigm
Normal Paradigm : It is natural to get some defects/rejects in the process
Kaizen Paradigm : We must find out a way to avoid defects/rejects from the process
SEE
DO
GET
Zero Defect Quality (This
method is even better
than Six Sigma)
New Paradigms
Every defect you see
as an opportunity to do a
Poka-yoke
Focus on efficiency,
not deficiency
Focus on the process,
not on the people
Create a culture of
Zero error
5
9. What is Poka-Yoke?
“A Poka-yoke device is any mechanism that either prevents a
mistake from being made or makes the mistake obvious at a
glance”.
•As Shingo writes,
"The causes of defects lie in worker errors, and defects are
the results of neglecting those errors. It follows that mistakes
will not turn into defects if worker errors are discovered and
eliminated beforehand”
9
14. Lean Eliminates Non-Value Adding Activities
Value adding
Optimize
Necessary but
not value adding
Minimize
5%
5%
Primary focus of “traditional”
Primary focus of “traditional”
efficiency improvements
efficiency improvements
35%
35%
Primary focus of
LEAN improvements
Non value adding
WASTE
60%
Attack the NVA first and
Attack the NVA first and
reduce the NVA through
reduce the NVA through
further improve & eventually
further improve & eventually
eliminate it completely. A
eliminate it completely. A
process in general has around
process in general has around
95% Waste in the form of NVA
95% Waste in the form of NVA
16. 8 Types of Wastes
All alphabets are showing a kind of Waste -
D - Defects
O - Overproduction
W - Waiting
N - Needless Processing
T - Transportation
I - Inventory
M - Motion
E - Employee Creativity
16
17. Elimination of Wastes and Continuous Improvement
• • Total Productive
Total Productive
Maintenance
Maintenance
• • Value Stream Mapping
Value Stream Mapping
17
20. What is a Zero Defect Quality System (ZDQ)?
A quality concept to manufacture ZERO defects &
elimination of waste associated with defects, rejects,
rework, pilferage, etc.!
“ZERO” is the goal!
20
21. What is a Zero Defect Quality System (ZDQ)?
Based on a discipline that
defects can be prevented
Control the process so that defects
are impossible!
21
22. Cost of Defects?
There is always a cost associated with manufacturing defects!
Does it cost more to make processes better?
NO
Making processes better leads to reduced
12%
Rework
4%
Scrap
7%
Warranty costs
11%
Inspection costs
22
25. 1) Simple & Inexpensive
Poka-yoke devices must be simple in implementation and usage.
Closed
Cabinet
Transparent
Cabinet
They are often inexpensive as ideas of making the devices mistake-proof at
their workplace comes from the front-line workers who prevents errors in
the work being done.
25
26. 2) 100% Inspection
Only Point of Origin Inspection actually
eliminates defects, rejects, rework, etc.
“Focus on prevention, not detection”
• Catches errors
May include Switches that detect
miss-fed parts
-Pins that prevent miss-feeding
-Warning lights
-Sound signals
• Gives feedback before processing
• No risk of making more defective
product
Process with Zero Defects
Detect Error
By combining Check and Do in
the ZDQ approach
Feedback / Corrective Action
26
27. ZDQ / Check & Do / Point of Origin Inspection
27
28. 100% Inspection
a) Go through the passage. Count F’s both small & capital
letters
b) Do not go through the passage a second time because
that would be 200% Inspection not 100% Inspection
28
29. Count F’s
The necessity of training farm hands for first class
farms in the fatherly handling of farm live stock is
foremost in the minds of farm owners. Since the
forefathers of the farm owners trained the farm
hands for first class farms in the fatherly handling of
farm live stock, the farm owners feel they should
carry on with the family tradition of training farm
hands of first class farms in the fatherly handling of
farm live stock, because they believe it is the basis of
good fundamental farm management.
29
31. 100% Inspection
100% Inspection is not as effective as
the Source inspection, this
methodology is more effective than
statistical sampling which does not
provide feedback in reducing defects
31
32. 3) Immediate Feedback
The third qualifier provides immediate feedback, whereas traditional method provides
feedback after the whole process is finished
ZDQ sends the operator a signal and alarms the person that an error has happened!
ZDQ Inspections = Immediate Feedback
32
36. Think Different – Poka-Yoke
Transparent
Toaster
It allows you to see the
bread while it is toasting
so you just have to take
it out when the color is
right.
VISUAL – Enjoy your
toast, don’t burn it
36
37. Innovate – Poka-Yoke
Laser Scissors
Cutting a straight line
has never been easier
Just aim the pin-point
laser and follow the line
Voila, no jagged
edges, no jay-walking
on paper
37
39. Poka-Yoke Systems Govern the Process
Two Poka-Yoke System approaches are utilized in manufacturing
which lead to successful Zero Defect Quality (ZDQ):
1. Control Approach
Shuts down the process when an error occurs
Keeps the “suspect” part in place when an operation
is incomplete
2. Warning Approach
Signals the operator to stop the process and correct the problem
39
43. Methods for Using Poka-Yoke
Poka-yoke systems consist of three
primary methods:
1. Contact
2. Counting
3. Motion-Sequence
43
44. 1) Contact Method
“A contact method functions by detecting whether a sensing
device makes contact with a part or object within the
process”
Cylinder present
Missing cylinder;piston fully
extended alarm sounds
Limit switches are pressed when
cylinders are driven into a piston.
The switches are connected to pistons
that hold the part in place
In this example, a cylinder is missing
and the part is not released to the next
process
Cannot proceed
to next step.
Contact Method using limit
switches identifies missing
cylinder.
44
46. Energy Contact Devices
Photoelectric switches can be used with objects that are translucent or
transparent depending upon the need
Light
Transmitter
Receiver
Object
If object breaks the transmission, the machine is signaled to shut down
46
47. Contact Device
An example of a
contact device using
a limit switch. In
this case the switch
makes contact with a
metal barb sensing
it’s presence. If no
contact is made the
process will shut
down
47
48. Contact Methods
Do not have to be high tech!
The devices can be as simple as guide pins or blocks that do not allow
parts to be seated in the wrong position prior to processing
Take advantage of parts designed with an uneven shape!
- A work piece with a hole a bump or an uneven end is a perfect
candidate for a passive jig
- This method signals to the operator right away that the part is not in
proper position
48
49. 2) Counting Method
Count the number of parts or components required to complete an
operation in advance.
If operators finds parts leftover, they will know that something has been
omitted from the process
“I have an extra
part. I must have
omitted a step!”
49
50. 3) Motion-Sequence Method
- Method uses sensors to determine if a motion or a step in a process has
occurred
- If the step has / has not occurred out of sequence, the sensor signals a
timer device to stop the machine and signal the operator
If movement does not occur, the switch
signals to stop the process or warn the
operator
50
51. Motion-Sequence Method
Each step of the machine cycle is wired to an indicator board and a timer.
If each cycle of the machine is not performed within the required “time”
and “sequence”, the indicator light for that step will be turned on and the
machine will stop
Machine
Indicator Board
51
52. Types of Sensing Devices
Sensing devices that are traditionally used in poka-yoke
systems can be divided into three categories:
1. Physical contact devices
2. Energy sensing devices
3. Warning Sensors
Each category of sensors includes a broad
range of devices that can be used depending
on the process
52
53. A) Physical Contact Sensors
These devices work by physically touching something. This can be a
machine part or an actual piece being manufactured.
In most cases these devices send an electronic signal when they are touched.
53
54. B) Energy Sensors
“These devices work by using energy to detect whether or not any
defect has occurred”
Fiber optic
Vibration
Photoelectric
54
55. C) Warning Sensors
Warning sensors signal the operator that
there is a problem
These sensors may be used in conjunction
with a contact or energy sensor to get the
operators attention
Color Code
Lights
Lights connected to
Micro switches & Timers
55
56. 3 Rules of Poka-Yoke
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!
56
60. 3) Source Inspection
Detects mistakes before they
become defects
Transformation = Quality production right the first time
Inspection….eliminated ???
Transport
Storage
Delay/wait
Dedicated lines
One piece flow
60
62. Principles of Poka-Yoke
• Elimination seeks to eliminate the possibility of
error by redesigning the product or process
• Replacement substitutes a more reliable process
to improve consistency
• Prevention engineers the product or process so
that it is impossible to make a mistake at all
62
63. Principles of Poka-Yoke
• Facilitation employs techniques and combining
steps to make work easier to perform
• Detection involves identifying an error before
further processing occurs to quickly correct the
problem
• Mitigation seeks to minimize the effects of errors
63
65. 100-1000-10000 Rule
The 100-1000-10000 rule states that as a product or service moves
through the production system, the cost of correcting an error
multiplies by 10
Cost
Activity
Order entered correctly
Rs. 100
Error detected in billing
Rs. 1000
Error detected by customer
Rs. 10000
Dissatisfied customer shares the experience with others the costs is
Rs.1,00,000
65
66. How do defects impact cost?
Operation A
Source
In-process
Inspection
Operation B
Downstream
Final
Inspection
Customer
Downstream Process
Rs. 100
RS. 1,000
Rs. 10,000
Rs. 1,00,000
Rs. 10,00,000
Very Minor
Minor Rework
More Defects
more Rework
Significant
rework delay,
Reschedule
Reputation,
Loss of
market share
Incremental Cost
66
69. What Causes Defects?
Human Mistakes
“Simple errors-the most common cause of defects-occur
unpredictably”
The goal of ZDQ is zero!
Make certain that the required
conditions are in place and
controlled to make acceptable
product 100% of the time
69
71. To Prevent Mistakes To occur
To prevent mistakes, install error proofing devices
Checklists
Dowel and locating pins
Error & alarm detectors
Limit or touch switches
Detectors, readers, meters, counters
71
72. Poka-Yoke Format
POKA-YOKE SHEET
COMPANY NAME
Problem:
Shutdown
Prevent Error
Solution:
Control
Key Improvement:
Detect Error
Before
Picture
Alarm
After
Picture
72
