Mistake Proofing

1. Tata Steel Slide
Poka-Yoke (Mistake Proofing)
TQM Academy
Webinar
06 July, 2020

2. Tata Steel Slide 2
Total Quality Management
About TQM Academy
Vision: To create ambassadors for journey of business excellence!
Mission: To ingrain systems thinking & process approach and drive culture of improvement / innovation
leading to superior business results.
TQM Academy was initiated in 2016 to build deeper understanding of improvement methodologies in the organization.
The effort has been to create a congregation of experts equipped with intuitive power to analyze and solve complex
business problems innovatively; the proclivity to imbibe structured decision making, in their DNA of operation.
In the last 4 years, a total of 700+ people were groomed under the aegis of the ambitious TQM academy through
classroom based training programs, enriching the ‘human capital of Tata Steel.
To keep pace with the technological developments & the dynamic business needs and to stay ahead of the curve in
innovation, courses are consistently revised - embedding new tools & techniques that would play a pivotal role in
addressing the business context of today & tomorrow.

3. Tata Steel Slide 3
Total Quality Management
Poka-Yoke (Mistake-Proofing) :
About the course
▪ This 2 Hours course on Poka-Yoke or Mistake-proofing aims to acquaint participants with the essentials,
processes, methods, and gadgets important to wipe out mistakes. This session will provide a systematic
understanding of Mistake-Proofing which leads to cost savings and increased productivity in the organization.
Outcomes:
▪ Enhance ability to analyze different Errors and Mistakes
▪ Help demonstrate structured approach to implement Poka-Yoke

4. Tata Steel Slide
Certification criteria
▪ Candidate must secure at least 70% marks in MCQ test
▪ Post the training program, participants to complete assignment/project using concepts covered in the course.
Completed assignments will be reviewed by a panel of experts.
▪ Based on successful completion of the assignment/project work and meeting the qualification requirements in
the examination, participants will receive course completion certification.
4
Total Quality Management

5. Tata Steel Slide
Ground Rules
✓ Participants must comply with all COVID-19 mandatory rules.
✓ Participants are requested to ensure good/reliable network connectivity at their end.
✓ Participants can use “Raise your hand” option to clarify queries during the training program.
✓ Participants are requested to complete all the exercises given in each session.
✓ Participants are encouraged to interact among their groups and also with other groups.
5
Total Quality Management

6. Tata Steel Slide
POKA –YOKE
(Mistake Proofing)
Episode - 4

7. Tata Steel Slide 7
Agenda (2/2)
S.No Agenda Item Duration Time Faculty
1 Welcome Participants 5 Min 10:00-10:05
Rakesh Kumar
Shakti R Baral
2 Introduction, History & Background of Poka-Yoke 20 Mins 10:05-10:10:25
3 QUIZ Questions and Discussion 5 Min 10:25-10:30
4 Need and Principles of Poka-Yoke 20 Min 10:30-10:50
5 QUIZ Questions and Discussion ( Break for 5 Min) 10 Min 10:50- 11:00
6 Types of Poka-Yoke, Implementation Method (Case study Example) 20 Min 11:00-11:20
7 QUIZ Questions and Discussion 10 Min 11:20-11:30
8 Intelligent/Smart Poka-Yoke 15 Min 11:30-11:45
9 Revision : By Qapsule Video Streaming and Conclusion 15 Min 11:45-12:00
Total Quality Management

8. Tata Steel Slide
Total Quality Management 8
Introduction, History & Background of Poka-Yoke

9. Tata Steel Slide
Introduction, History & Background of Poka-Yoke:
9
POKA-YOKE
A poka-yoke is any mechanism/device in any process that helps
an equipment operator avoid (yokeru) mistakes (poka).
A Japanese concept on ‘Zero Defect Product’
Awareness
Detection
Prevention
Our customers & Consumers
(Defects)
Our employee
(injuries)
WASTE
(Cost, Time)
Adversely affect
POKA
MISTAKE
YOKE
AVOID
Poka-Yoke way to
avoid mistake
Traditional way to
avoid mistake
Reprimand
Retrain
Motivate
Error prevent at Source
Defect Detect before Delivery
POKA-YOKE

10. Tata Steel Slide
Introduction, History & Background of Poka-Yoke:
10
Shigeo Shingo invented (in 1961) the Japanese concept called Poka-Yoke
(when he was one of engineers at Toyota Motor Corporation)
Baka-Yoke Fool-Proofing/ Idiot Proofing
1961-(ZQC)
Poka-Yoke Mistake-Proofing/ Error-Proofing/ Fail-Safe
1963-(ZQC)
Mr. Shigeo Shingo
(1909-1990)
Dishonourable and offensive connotation
*ZQC-Zero Quality Control
Terms of Poka-Yoke:
Prevention Detection
Poka-Yoke devices fall into two major categories

11. Tata Steel Slide
Introduction, History & Background of Poka-Yoke:
11
Total Quality Management
(Integrated Quality Management & Control)
*CTQ-Critical to Quality, PC-Process Capability, CPk-Capability Index, LCA-Low cost Automation
Supplier
Customer
Zero Defect
Products & Services
By Capturing & Acting
on 100% Complaint
Concept of
100% Inspection
CTQ is inspected By
• Stage Inspection
• SPC( PC>1.66 CPk)
• Quality Audit
• Manual Inspection
Method to Capture
100% stage Inspection
• Poka-Yoke
• LCA
• Vision Control
• Doc Audit
• Inspection using
instrument manually
Achieved by
(Poka-Yoke: Starts with Inspection)

12. Tata Steel Slide
Introduction, History & Background : ( Timeline: SPC-1950, ZQC-1961, PY-1963….)
12
Mr. Shigeo Shingo, started working on ‘zero
defect products’method.
SPC, 1950
ZQC, 1961
Poka-Yoke, 1963
ZQC tries to achieve zero defects in all products.
Poka-Yoke : A Device or method that is able to
detect as well as prevent defects/errors
SPC
Process Input Control
STATISTICAL SAMPLING:
SOME PRODUCT
UNTESTED
CUSTOMER RECEIVE:
DEFECT PRODUCT
Disadvantage
ZQC
Zero Defect Product
CUSTOMER
SATISFACTION
COST REDUCTION
(SCARP,REWORK,DOWN TIME)
Advantage

13. Tata Steel Slide
Introduction, History & Background :
13
Quality
Improvement
Approach
Traditional
Approach
ZQC
Approach
Initial
Inspect
JUDGEMENT INSPECTION
INFORMATIVE INSPECTION
(SQC, SUCCESSIVE
CHECK,SELF CHECK
SOURCE INSPECTION (SI)
1
Quick
Feedback
2
100%
Inspect
3
Poka-Yoke
4
Plan
Do-
Check
Act
This cycle catches
and corrects defects after
they occur, but it can’t make
sure that work is done
according to plan in the first
place
The ZQC approach integrates
the Check and Do stages.
This gives instant
feedback so problems can be
corrected before defects
happen
ERROR CORRECTION
APPROACH AT SOURCE
SUB-STEPWISE INSPECTION
INTEGRATED APPROACH:
SI, FEEDBACK,100 %
INSPECTION
Device or Method

14. Tata Steel Slide
Introduction, History & Background :
14
Inspection system:
JUDGEMENT INSPECTION INFORMATIVE INSPECTION SOURCE INSPECTION
-Based on DOWNSTREAM Inspection
-Drawback- inefficient feedback
-Based on FEEDBACK system
-Objective: Inspection to reduce
defects
-Based on UPSTREAM Inspection
-Objective: Inspection to
discover defects before delivery
(Traditional )
-Objective: Inspection to eliminate
defects (Most effective)
POKA–YOKE (MISTAKE PROOFING)
-Drawback-Inefficient for source
end
-Drawback- unavailability of
skilled manpower at source end

15. Tata Steel Slide
Introduction, History & Background:
Authors Definition
Saurin et al. ;
Vidor and
Saurin
PY is a system or device for prevention and detection of abnormalities
that affect product quality and operators’ health and safety.
Being made of physical, functional or symbolic barriers it contributes to the
reduction of maintenance of stability and variability processes.
15
Definition of Poka-Yoke by different Author:

16. Tata Steel Slide
First Poka-Yoke Device:
16
Shingo suggested a solution that become the first Poka-Yoke device when Shingo visited Yamada electric
plant in Japan.
Empty Tray Spring assemble to switch
Problem at Plant:
The company had a problem with a
missing spring attached to a switch.
Solution Implemented:
The problem was solved by a small tray placed in front
of the operator where he needed to put only two springs
from the big box.
Thus, after the assembling process if nothing was left, it
meant that all the springs were in place.
1
2
2 Springs

17. Tata Steel Slide
POKA YOKE
DIVERSITY IN USE
Poke-Yoke can be used in
manufacturing industry, service
industry etc.
FOCUSSED SOLUTION TO
HUMAN ERRORS
The causes of defects lie in worker
errors, and defects are the results of
neglecting those errors
A JAPANESE
IMPROVEMENT STRATEGY
Poka-yoke gives a strategy and policy
for preventing as well as detecting
defects.
CONTINUAL
IMPROVEMENT
It can be applied on any mechanism or
idea that either avoids the mistake
from being made or makes the mistake
easily identify at a glance.
Characteristics of POKA-YOKE:

18. Tata Steel Slide
Can we change the behavior of human beings for not making mistakes?
18
Three common misunderstandings
• Attentiveness can prevent mistakes
• Education & Training can prevent mistakes
• Multi-fold inspection can prevent mistakes

19. Tata Steel Slide
QUIZ Time 1: Count Number of letter ‘e’ in the passage ( in 2 mins)
19
In these times of COVID-19, one of the most common clichés bandied about by op-ed writers and TV anchors is:
“Every crisis brings with it an opportunity”. The question is: Opportunity for whom or for what? In this case, the
opportunity has been for an inanimate object and hitherto a longstanding enemy — single-use plastic (SUP) — to
thrive and proliferate on an unprecedented scale on the back of the global pandemic.
If you were to take stock of the kinds of waste products you attempted to dispose of in the last 24 hours, you would
surely recall trying to get rid of, safely or otherwise, an increasing number of COVID-specific, SUP-based products.
Central to our new, hyper-hygienic way of life has become the increased dependence on non-recyclable items such as
plastic-lined masks, gloves, hand sanitizer bottles and other personal protective equipment. There has also been a
steep increase in day-to-day items such as plastic bags and delivery packaging. In 2018, a report by McKinsey
estimated that, globally, we generate 350 million tonnes of plastic waste a year of which only 16 per cent is recycled.
Today, the WHO estimates that the planet is using about 89 million masks and 16 million gloves each month – the
amount of plastic waste it’s generating is much higher than that estimated in the McKinsey report two years ago. To
complete the stark picture, The Guardian recently reported that there are possibly more masks than jellyfish in the
oceans today.
100% inspection is not 100% effective
Passage:

20. Tata Steel Slide
Total Quality Management 20
Need and Principles of Poka-Yoke

21. Tata Steel Slide
Need and Principles of Poka-Yoke:
21
Why mistakes occur ?
and
What Human factors make mistakes?
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“
…………..By Shingo
Error Defect
Act of Mistake
Relation between Mistake, Error and Defects:

22. Tata Steel Slide
Relationship between Defects and Human Error: By Ice-Berg Model
22
Visible
Hidden
Human Errors
Defects
Lack of Experience
and Many More
Slowness
Misunderstanding
Forgetfulness

23. Tata Steel Slide
Need and Principles of Poka-Yoke
23
Mistake category Cause examples
Causal factors fatigue, poor lightning, urgency, interruption
Project phase design, fabrication, assembly
Ergonomic factors perception, decision, action, skill,training
Human error probability error frequency, human performance
Stress factor workload, occupational change, or frustration
Mistake consequences injury, loss, damage
Function or task welding, milling, detailing, inspecting
Behavioral factors communication, motor processes,perception
Corrective action rework, repair, scrap
Definition of Mistake : an act or judgement that is misguided or wrong
Mistake Category:

24. Tata Steel Slide 24
Classification of Human errors:
FORGETFULNESS INADVERTENT ERRORS
MISUNDERSTANDING SLOWNESS
IDENTIFICATION
LACK OF
STANDARDS
LACK OF EXPERIENCE SURPRISE ERRORS
WILLFUL ERRORS INTENTIONAL ERRORS
1
2
3
4
5
6
7
8
9
10
HUMAN
ERROR
Need and Principles of Poka-Yoke

25. Tata Steel Slide
Need and principles of Poka-Yoke: RACE Model
25
REDUCE ACT COST ENHANCE
R A C E
Reduce Inventory
Eliminates Scrap,
Rework, and Repair
Reduced
rework/repair are
only necessary when
work was not done
correctly the first
time
Need to expedite for
achieve KPI
Improved
Productivity
High Level of Quality
Safe workplace/less
injury
Efficient
manufacturing output
Zero defect product: No
return of product
Automated system
development for
reducing Man-Machine
interface
Enhance customer
satisfaction.
Utmost priority on
Defect free product
to customers
On time delivery of
products
What is the need of Poka-Yoke:

26. Tata Steel Slide
Principles of Poka-Yoke: Poka-Yoke Functions
26
Small
Tasks Risks
Functions
Required
Memory
Perception
Motion
Effects
Operations
Mistake
Remove work
susceptible to human
mistake from the
process
Make the mistake
prone operations
unnecessary
Replace the human
operations with more
reliable machines
Automate Operations
Make the operation
easier for workers to
perform
Distinguish part
boxes by color
coding
Ensure that the
abnormalities caused
by mistake are
detected
Equipment to detect
workers’ motion and
make an alarm
Mitigate the effects of
mistake
Electric fuse that
prevents equipment
breakdown
Elimination Replacement Facilitation Detection Mitigation
Prevent the occurrence of human
mistakes which may cause
troubles
Prevention
Minimize the effects of human
mistake
Detection
Mistake Proofing
Losses Large
Abnormalities

27. Tata Steel Slide 27
Principles of Mistake Proofing: Summary
Mistake
Proofing
Prevention
of
Occurrence
Minimization
of Effects
Elimination
Replacement
Facilitation
Detection
Mitigation
Task Elimination
Risk Elimination
Automation
Support System
Simplification
Distinction
Adjustment
Record & Verify Motion
Restrict Motions
Verify Results
Redundancy
Failsafe
Protector

28. Tata Steel Slide
Elimination
28
Remove work susceptible to human mistake from the process:
Wire
Battens
Product
Nylon Belts

29. Tata Steel Slide
Elimination
29
Elimination
Tasks
Risks
Mix or Assemble
Set Conditions
Move
Hand-off
Fill-in
Verify or Adjust
Mixing or assembling more than
one objects into one
Eliminate mistake prone tasks
Moving to objects or transferring
Transferring information or
objects from a person to another
person
Getting information and filling it in
a format
Checking ot adjusting objects or
schedules
Tasks/Risks to be Eliminated Sub-principles
Task Elimination
Risk Elimination
Set conditions depending on the
situations
Eliminate risks inherent in objects
or objects themselves
Examples
Mistake Mistake-Proofing
Forgetting to
put battens
between a
product and its
lifting wires so
as to prevent
damage to the
product
Use of nylon bands
instead of wires ,
thus making the
battens unnecessary
by removing the
property which
generates the
operation
Mistake Mistake-Proofing
Touching a high
temperature
pipe and getting
burnt
Make the pipe safe
by covering it with
insulating material

30. Tata Steel Slide
Elimination
30
In many cases, process/equipment design
must be changed drastically.
Elimination solution can have a great side-
effect on cost, productivity and performance.
This side-effect must be considered.

31. Tata Steel Slide
Replacement
31
Replace the human operations with more reliable machines:
Sub-assembly product
Conveyor
Limit Switch
Sense the shape Light the lamps

32. Tata Steel Slide
Replacement
32
Replacement
Memory
Perception
Motion
Functions to be Replaced Sub-principles
Automation
Examples
Mistake Mistake-Proofing
Misreading a
work order
sheet and
installing the
wrong parts in
the sub-
assembly
Sense the shape of
the sub-assembly
product
mechanically or
electrically and to
light lamps on the
appropriate parts
boxes
Mistake Mistake-Proofing
Forgetting to do
a part of the
operations
Use a table
showing the
sequence and
contents of the
operations, thus
making it
unnecessary for
workers to
memorize them
Support System
Use Automation to replace
completely a particular human
operation with machines
Give support tools such as
checklist, reminders, guides or
samples to help human beings
to perform the operations more
reliably

33. Tata Steel Slide
Replacement
33
Various methods can be considered
depending on the number of functions that
are replaced.
To replace all functions leads to large-scale
and unrealistic solutions.
It is essential to focus on mistake-prone
functions in the operations and replace them.

34. Tata Steel Slide
Facilitation
34
Make the operations easier for workers to perform:
Simplification
Distinction
Adjustment
A
Common ID Code
Work Order Sheet
Parts Box

35. Tata Steel Slide
Facilitation
3
Facilitation
Memory
Perception
Motion
Functions to be Facilitated Sub-principles
Simplification
Examples
Mistake Mistake-Proofing
Selecting the
wrong parts
Make a mark on
each parts box
consistent with a
corresponding mark
on the work-order
sheet
Mistake Mistake-Proofing
Misunderstandi
ng the types of
parts
Color coding of the
parts and the
arrangement of
parts boxes so as
to keep away
separate similar
parts
Distinction
Decrease the number of
changes or differences
Distinguish changes or
differences from each other
Distinguish changes or
differences from each other
Adjustment
Mistake Mistake-Proofing
Misreading the
work-order
sheet
Making the
symbols or
characteristics
which show the
types of parts
bigger and clearer

36. Tata Steel Slide
Facilitation
36
Each solution of Facilitation has limited
effectiveness, its cost and side-effects to
operations are minimal
Do not use one method of Facilitation alone,
apply many methods together.
List as many ideas as possible and evaluate
them.

37. Tata Steel Slide
Detection
Ensure that the abnormalities caused by human mistake are
detected and suitable corrective action is taken
37
Detect taking parts
Photo-electric switch
Parts boxes
Stop Tools from working

38. Tata Steel Slide
Detection
3
Detection Negative
Positive
Abnormality in
Results
Abnormalities to be detected Sub-principles
Record and Verify
activity and indicate
abnormality
Examples
Mistake Mistake-Proofing
Misreading
an
operation
order sheet
and
selecting
wrong part
Use photo-electric switches
attached to the parts boxes
to sense which parts the
worker has picked and
compare the results with
each other or with pre-
process operation contents
and automatically suspend
operation of assembly tool
if there is any disagreement
Mistake Mistake-Proofing
Misreading an
operation order
sheet and
selecting
wrong part
Change the shapes of
the parts so that the
wrong parts cannot be
fitted to the sub-
assembly product
Decrease the number of
changes or differences
Restrict motions to let persons
notice abnormality
Sense shape/quality/state of
work objects at a certain point
in motion/time
Mistake Mistake-Proofing
Misreading
an operation
order sheet
and
selecting
wrong part
Sensing the shape of the
product on its way to the
next process, comparing
the results with the
standard and stopping the
production line if there is
any disagreement
Abnormality
in
activity
Omission of necessary
activity (steps)
Unnecessary activity (step)
Abnormality
in activity of
persons or
objects
Abnormality in results of
motions such as
shape/quantity/state of objects
Restrict Motions
Verify results and
indicate abnormality

39. Tata Steel Slide
Detection
39
Late detection
means large
correction
costs.
Establish
detection
techniques.
Hardware has
an important
role in
detection.
Prevent
failure of
hardware for
detection.
Mistakes are
not prevented
by detection.
Apply
Prevention of
Occurrence
solutions at
the same time

40. Tata Steel Slide
Mitigation
Mitigate the effects of the mistake by incorporating functional redundancies or
using shock-absorbing materials
40
Main Workshop
Switch
Switch of the
equipment
Foreman Worker

41. Tata Steel Slide
Mitigation – Chain of Effects
41
Mistake Malfunction Malfunction Malfunction
Forgetting to switch
off the power supply
The power supply is
not cut-off
The motor does not
stop
The motor does not
stop
Unsafe Status
The temperature of
the motor becomes
high
Loss
Redundancy Fail Safe
Protector The motor is burned
out
Malfunction
–
unsafe
state
–
loss
chains

42. Tata Steel Slide
Mitigation
4
Mitigation
Malfunction-
malfunction
chain
Malfuncti
on-
unsafe
state-loss
chain
Effects to be Mitigated Sub-principles
Redundancy
Examples
mistake mistake-Proofing
Burning out the
motor of a
production
machine by
forgetting to
switch off its
power supply
Make it the workers’
job to operate the
switch on the machine
itself and the
foreman’s job to
operate the main
workshop switch
mistake mistake-Proofing
Burning out the
motor of a
production
machine by
forgetting to
switch off its
power supply
Fit the machine with a
fuse which cuts-off the
power supply when
the motor temperature
reaches a certain level
Have a safety factor, or
make same function
parallel
mistake mistake-Proofing
Burning out the
motor of a
production
machine by
forgetting to
switch off its
power supply
Cover the posts with
shock absorbing
materials
mistakes cause malfunction
in operations subsequently
Malfunctions in operations
cause losses
Unsafe State
Loss
Failsafe
Incorporate shock-
absorbing
material/equipment
Protector
Make unsafe conditions
not produce losses

43. Tata Steel Slide
Mitigation
43
It is important to
prevent undesired
effects
Focus on the chain of
effects which leads to
the undesired effects
Occurrence of
mistake is not
recorded
Apply Detection
Solutions at the same
time

44. Tata Steel Slide
QUIZ Times:2
44
1. Mitigation is which type of Poka-Yoke( Preventive/Detective)? What are its sub-principles?
2. Elimination is which type of Poka-Yoke ( Preventive/Detective)? What are its sub-principles?
3. Poka-Yoke was invented By ?
5. How many functions/types are there in replacement type Poka-Yoke?
4. How many sub-principles/types are there in facilitation type Poka-Yoke?

45. Tata Steel Slide
Total Quality Management 45
Types of Poka-Yoke,
Implementation Method (Case study Example)

46. Tata Steel Slide
Implementation Method and Types of Poka-Yoke:
46
Implementation:
Three steps for mistake Proofing
How can we overcome the difficulties in implementing mistake proofing?

47. Tata Steel Slide
Three Steps for mistake Proofing
Step-1
• Identifying improvement
opportunities
Step-2
• Generating Solutions
Step-3
• Evaluating and selecting solutions
47

48. Tata Steel Slide
Difficulties at Step 1-3
Step 1 : The mistakes to be mistake-proofed not well identified
Step 2 : Lack of openness for generating alternative solutions
Step 3 : Large number of the generated solutions
48

49. Tata Steel Slide
Look in Best Solution Directions
49
Problem
Innovative Solution
Best Solution Direction
Solution - 1
Solution - 2
Solution - N

50. Tata Steel Slide
How to make a Consensus
One-dimension Viewpoint
Member Opinion Reason
A
Solution 1 is
best
Effective
B
Solution 2 is
best
Small cost
C
Solution 3 is
best
Easy to
continue
Soluti
on
Effective
Small
cost
Easy to
continue
Soln -1 3 1 1
Soln -2 2 3 2
Soln -3 1 2 3
Multi-dimension Viewpoint
Competition by loudness Evaluation by logical thinking
50

51. Tata Steel Slide
Supporting Tools for Steps 1-3
Step 1 : Failure Modes and Effects Analysis (FMEA) and General Error Modes (GEM)
Step 2 : Questions for Generating mistake Proofing Solutions (QGEPS) and mistake
Proofing Solution Database (EPSD)
Step 3 : Solution Priority Number (SPN)
51

52. Tata Steel Slide
Step 1 – FMEA (Failure Modes and Effects Analysis)
Decompose to
Sub-processes
List Failure
Modes
Evaluate Risk
Priority Number
Decomposition Rule:
Operations for the same
work objects are
decomposed to the
same sub-process.
Use Sixteen General
mistake Modes
RPN:
mistake occurrence
possibility x Criticality of
effects x Degree of
localizing effects
Sub-process Failure Modes Effects
Cause
s
Risk
Priority
Number
Take parts A
Forget to take
parts A
1 1
Select the
wrong parts A
3 2
52

53. Tata Steel Slide
Step 1 : GEM (General Error Modes) ……. (1/2)
S.No. General Error
Modes
Corresponding Human Mistakes No. of
Mistakes
1
Omission
Forgetting to take out or set parts/materials.
Forgetting to operate buttons, valves, or switches.
292 (28.1%)
2 Excessive/
Insufficient
Repetition
Re-executing the finished work.
Excessively/ insufficiently repeating work.
2 (0.2%)
3
Wrong Order
Executing two sequential work operations in an
inverted order.
7 (0.7%)
4 Early/ Late
Execution
Beginning work earlier/ later than specified.
Ending work earlier/ later than specified.
2 (0.2%)
5 Execution of
Restricted work
Executing restricted work which is likely to cause
poor quality, injuries, or accidents.
11 (1.1%)
6 Incorrect
Selection
Selecting the wrong parts/ materials.
Using the wrong tools.
176 (17.5%)
7 Incorrect
Counting
Supplying the more material than specified.
Transporting less parts than ordered.
9 (0.9%)
8
Misrecognition
Misreading work-order sheets, meters, or records.
Failing to sense areas not to be approached.
165 (16.4%)
53

54. Tata Steel Slide
Step 1 : GEM (General mistake Modes) ……. (2/2)
S.No. General Error
Modes
Corresponding Human Mistakes No. of
Mistakes
9
Failing to Sense
Danger
Failing to sense items not to be touched.
Failing to sense areas not to be approached.
17 (1.7%)
10 Incorrect Holding
Holding a damageable part of materials/parts.
Holding tools the incorrect way.
3 (0.3%)
11 Incorrect Positioning
Setting parts in the wrong positions.
Transporting materials to the wrong place.
50 (5.0%)
12 Incorrect Orientation
Setting materials/parts the wrong way around.
Bending material to the wrong side.
102 (10.1%)
13 Incorrect Motion
Bending material too much.
Opening valve too fast.
1 (0.1%)
14 Improper Holding
Failing to ensure material/parts do not to move.
Dropping parts, products, or tools.
20 (2.0%)
15 Inaccurate Motion
Setting materials/parts in inaccurate positions.
Tightening bolts to inaccurate torques.
88 (8.8%)
16
Insufficient
Avoidance
Knocking parts/tools into each other.
Falling/stumbling.
Touching machine switches without intention.
60 (6.0%)
54

55. Tata Steel Slide
Step 2 : QGEPS (Questions for Generating Error Proofing Solutions)
55
Elimination
Can we eliminate the mistake-
prone process?
Detection
Can we detect abnormal
motions?
Can we eliminate harmful
objects?
Can we make abnormal
impossible?
Replacement
Can we automate the process?
Can we detect abnormal
items/states?
Can we provide the supporting
tools like checklists/ gages/
samples?
Mitigation
Can we make
operations/items redundant
to mitigate the effects?
Facilitation
Can we simplify changes/
differences in the operations?
(Standardization, code
matching, etc.)
Can we control the transition
to the dangerous states?
Can we distinct
changes/differences in the
operations? (Colour coding,
unique shape, etc.)
Can we make protections for
the damages caused by the
dangerous states?
Can we adjust the work objects/
space to human ability?

56. Tata Steel Slide
Step 2 : EPSD (Error Proofing Solution Database)
56
EP Example Mistake: Forgetting to put battens between a product and its
lifting wires so as not to damage the product.
Improvement: Use nylon bands instead of wires, thus making the battens
unnecessary by removing the property which generates the operation.
Before: After:
Effects: Costs:
Date: Proposed by: Supervisor Manager Reg. No.
Process:

57. Tata Steel Slide
Step 3 : SPN (Solution Priority Number)
57
Solution Priority Number = Effectiveness x Cost x Implementation
➢ Effectiveness  1 (Ineffective) to 3 (Very effective)
➢ Cost  1 (High) to 3 (Low)
➢ Implementation  1 (Difficult) to 3 (Easy)

58. Tata Steel Slide
SPN : Effectiveness Scoring
58
Score Definition
3
Very Effective : Probability of the mistake can
be eliminated, or chance of detection can be
perfectly improved.
2
Effective : Probability of the mistake can be
reduced; however, it is still high. Chance of
detection can be improved; however, it is still
not enough.
1
Ineffective : Probability of the mistake can
not be reduced, and chance of detection can
not be improved.
Higher is
better

59. Tata Steel Slide
SPN : Cost Scoring
59
Score Definition
3
Low : Within daily operation budget.
No specific budget is needed.
2
Moderate : Department level budget is
needed.
1 High : Company level budget is needed.
Higher is
better

60. Tata Steel Slide
SPN : Implementation Scoring
60
Score Definition
3
Easy : No training is needed.
No Resistance is expected.
2
Moderate : Training course is needed.
Some resistance is expected.
1
Difficult : Culture change is needed.
Strong resistance is expected.
Higher is
better

61. Cases of Mistake Proofing

62. Case 1: Electronic Parts Delivery
A worker inputs a parts
number and then the
pallete automatically
comes to the front of
the worker.
The worker looks at the
parts box number and
take the corresponding
box on the pallet.
Pallet : A pallet contains several trays
Part Box
Number
Parts
Number
Parts
Box

63. Step I: FMEA
Sub process Failure Mode
(Possible mistake)
Effects (Results
caused by the
mistake)
Input parts number Input the wrong
number.
The wrong parts on the
different pallet.
Look at the displayed
parts box number.
Misread the displayed
number.
The wrong parts having
a similar parts box
number on the same
pallet
Take the parts box. Take the wrong parts
box.
The wrong parts having
a continuing number on
the same pallet at the
upper level where it is
difficult to identify the
parts boxes.

64. Step II: QGEPS
Questions for Generating
mistake Proofing Solutions
mistake Proofing Solutions
Can we automate the process? Attaching the lamps to the shelf,
which automatically shows the
corresponding parts box.
Can we distinct changes/
differences in the operations?
Attaching labels to the palletes to
distinguish parts baoxes.
Can we detect abnormal items/
states?
Comparing the check digit on the
selected parts box with that shown
on display.
Can we make operations/ items
redundant to mitigate the effects?
Preparing spare parts in the
assembly process
…….. ……..

65. Step III: SPN
mistake Proofing Solutions Effectiven
ess
Cost Implem
entatio
n
SPN
Attaching the lamps to the shelf,
which automatically show the
corresponding parts box.
3 1 3 9
Attaching labels to the pallets to
distinguish parts boxes.
2 3 3 18
Comparing the check digit on
the selected parts box with that
shown on the display.
1 2 2 4
Preparing spare parts in the
assembly process.
1 2 3 6
….. …. ….. …. ….

66. Case 1: Effects of mistake
Proofing
Application of
mistake Proofing
Solutions
0
50
100
150
200
250
10 11 12 1 2 3 4 5 6 7 8 9 10 11
Fraction
Defective
(ppm)
Months

67. Case 2: Electronic Product Assembly
• The final – assembly process of an electronic product
• Due to a very small lot size, the complete assembly is
performed by just one worker
• Major product components are supplied as necessary,
although small parts like screws, washers and labels are
provided in parts boxes in lump.
• In the next manufacturing step the assembled product
undergo the final inspection, with 55% of the defects being
caused by human mistakes.

68. Step I
N
o.
Sub Process Failure
(mistake)
Effects Causes Frequency of
mistake
Occurence
Severity
of
Effects
Degree of
Localizing
Effects
RPN
Exper
ience
Proba
bility
Detec
tion
Mitigati
on
1 Take Parts A Omission Missing
Parts A
0 0 2 0
2 Take a screw from
parts box
Omission Missing
Parts A
Repetition of
similar procedures
0 0 2 0
Incorrect
selection
Parts A
looseness
Ambiguous
identifications
Complex relation
to order sheets
0 1 4 4
3 Inspect Screw’s
appreance
Omission Defect in
appearance
Not a main job
No motions
0 1 3 3
4 Take a spring from
parts box
Omission Parts A
looseness
Repetition of
similar procedures
Not a main job
2 1 3 9
Incorrect
selection
Parts A
looseness
Ambiguous
identifications
Complex relation
to order sheets
0 1 4 4
5 Inspect spring’s
appearance
Omission Defect in
appearance
Not a main job
No motions
0 1 3 3
One hour work was decomposed to about 200 sub process.
About 70 failure modes were identified to be mistake proofed.

69. Step II & III
Human mistake mistake Proofing Solutions
Forgetting Screws/
Washers
1. Procedure standardization, i.e. the work order numerically illustrates a
work instruction/ arrangement of parts boxes according to their
respective order.
2. Keying the work instruction figures to the part boxes by attaching the
same labels.
3. Preparing screws/ washers for one product in a partitioned pallete
before assembly (Method 1 and 2 were applied to injunction with this
pallete).
Selecting the wrong
screws/ washers
Forgetting to tighten the
temporary assembly
screws
1. Using special screws for temporary assembly, and after assembly,
exchanging them for normal screws, followed by tightening them one
by one.
2. Automatically counting the electronic driver’s number of operations for
each completed product, comparing them with a determined value,
and sounding an alarm if a disagreement exists.
Tightening screws to
improper torque
1. Using torque drivers.
2. Changing the order of work/ tools so that screws can be easily applied
and tightened.
Positioning or
orientation mistakes in
attaching lables
1. Showing realistic labels in work instruction figures.
2. Using special labeling tools.

70. 0
100
200
300
400
500
600
10 11 12 1 2 3 4 5 6 7 8 9 10
Fraction
Defective
(ppm)
Months
Case 2: Effects of mistake
Proofing
FMEA
Application of
mistake Proofing
Solutions 1-4
and 6-9
Application of
mistake Proofing
Solutions 5

71. Case 3: Mechanical Product Fabrication
• All final products were inspected and after frame
assembly, holing, tackling etc. with defective products
repaired and reworked.
• An human mistake caused a huge failure cost.
• The improvement activity for reducing the failure cost
was initiated according to the top management policy
“halve the failure cost.”

72. 72
Step I, II & III
Sub process of Flame
Assembly
mistake Modes Effects
1.
Omission
2.
Wrong
Order
3.
Excessive
Repetition
4.
Execution
of
Unnecessary
Work
5.
Incorrect
Selection
6.
Incorrect
Counting
7.
Misrecognition
8.
Incorrect
position
of
holding
9.
Incorrect
way
of
holding
10.
Dropping
11.
Inappropriate
release
12.
Falling
13.
Stumbling
14.
Inaccurate
adjusting
15.
Incorrect
description
16.
Making
unsafe
condition
17.
Touching
danger
Objects
Effects
on
Production
Function
Effcets
on
Failure
Cost
1. Prepare the equipment 0 1
2. Read the order 1 0
3. Pick up parts 4 2
4. Collect the parts to the
work bench
2 1
5. Draw lines on parts 3 1
6. Select the tool 1 2
7. Drill holes and take
burrs
4 1
8. Check the set position 2 0
9. Align the contour 1 2
10. Set parts on the
equipment
4 2
11. Pick up locators 0 0
12. Set and adjust the
locators
4 2
13. Drill the prepared
holes
2 2
14. Drill the prepared
holes at the locators
3 2
15. Take out the parts
from the equipment
2 1
16. Drill the other holes
by hands
3 2
17. Take burrs 0 0

73. Case 3: Effects of Mistake Proofing
0
50
100
150
200
250
300
350
400
0
50
100
150
200
250
300
350
400
4 5 6 7 8 9 10 11 12 1
No.
of
repairs/
reworks
No.
of
Kaizen
Proposals
No. of repairs/ rework No. of Kaizen Proposals
New Target Initial Target
The number of repairs/
reworks in a year
decreased from 20-30
to 1.
The number of kaizen
proposals increased
Actual
299
New
Target
400
Initial
Target
130

74. Case 4: Chemical Plants Operations
• Principal SOP were prepared.
• mistakes were analyzed only from the view point of
individual operator who made the mistake.
• About 60% of the mistake occurred when following
the SOP.
• Most mistakes were due to mistake-prone operations.

75. Steps I, II & III
• The sheet for analyzing the causes of operation mistakes
was changed to identify mistake-prone operation
methods.
• The operations where operators made mistakes or may
make mistakes were listed using FMEA
• Effective mistake proofing solutions against each listed
mistake-prone operation were implemented. (about 250
solutions in a half year)
• mistake proofing Solution Database
• mistake proofing Solution Contest

76. 0
5
10
15
20
25
30
35
40
45
1 2 3 4 5 6 7
No.
of
troubles
due
to
operators
Years
Case 4: Effects of mistake
Proofing
FMEA & mistake
Proofing
Solutions

78. Tata Steel Slide
Types of Poka Yoke Devices:
78
POKA
YOKE
Prevention
Based
Shut down
method
Control
method
Warning
method
Detection
Based
Contact
method
Fixed value
Method
Motion step
method
Poka-yoke can either detect defection after it has taken place or predict an error that is about to transpire.
Poka-Yoke Function: Elimination, Replacement, Facilitation
e
Poka-Yoke Function: Detection, Mitigation

79. Tata Steel Slide
Types of Poka Yoke: Prevention Based
79
• Sensing the anomalies before they happen and then signalling or stopping the process.
• It is a proactive mechanism
• Also called Regulating Function type PY
PREVENTIVE
BASED
PY
SHUTDOWN
Process equipment is cut-off preventing the production to operate with fault.
It assures 100% error free products.
E.g: Use of fuse in the electric circuit
CONTROL
WARNING
check if all the necessary conditions are met in order to move to next step of the
process.
It also ensures 100% error free products.
E.g: Washing machine doesn't start if door is open
Indicate . if the process is continued as is, defective products would be produced.
- 30% of error free products, as operator still needs to take actions.
- E.g: Elevator overload

80. Tata Steel Slide
Types of Poka Yoke: Detection Based
80
DETECTIVE
BASED
PY
CONTACT
The products are checked for any deviation from the structural
characteristics due to mechanisms which are in direct contact to the
products.
E.g: Many plugs, such as 3-pin plugs and USB plugs
FIXED VALUE
MOTION STEP
It checks if the number of steps involved in the process are all
performed or not.
E.g: egg tray
It checks that the operators don’t perform a step that isn’t a part of
the process.
E.g: colour coding of electrical wire
• Sensing the anomalies after they happen
• It is a reactive mechanism
• Also called Setting Function type PY

81. Tata Steel Slide
1 4
3
2
6
5
Poka
Yoke
Summary: Types of Poka Yoke
Shutdown
Control
Contact
Fixed Value
Sequential
Warning
Prevention Based Detection Based

82. Tata Steel Slide
Examples of Poka-Yoke in Daily Life
82
USB: Don’t get fit in
wrong direction
SIM Card: Cut from
corner to fit correctly
Floopy Disc: Cut mark
on upper side of CPU for
inserting floopy correctly
Hospital Line: Different
connector for different supplier
Plug & Sockets:
Different shapes of pin
Car:
• Head lamp, airbag alarm
• Central Locking, Child lock

83. Tata Steel Slide
Industry Based Examples:
83
Bio-Metric Attendance: Proxy
attendance are avoided,
Wrong Product detection: Alarm
trigger for defected product on
conveyor
Software Testing: the programs such
as lint, printfck, cchk, clash that examine
the syntax of programs and alert the
programmer to a possible mistake in
need of correction ( testing can not be
done other than developed programs)

84. Tata Steel Slide
Industry Based Examples:
84
Y-Strainer in water pipeline: waste
particle in water don’t go to customer
File Management: Wrong
sequence can be avoided
ATM Card Insert: Wrong
side( magnetic stripe/chip)
can not accept

85. Tata Steel Slide
Examples:
85
Circuit Breaker: when load
becomes too high, circuit is broken
to prevent overload heat fire
Hand Wash Tap: proximity sensor
act for water flow (Smart poka-yoke)
Hand Wash Tap: if Basin drain is
jammed, excess water enter into
the Hole on upper side of basin to
avoid overflow of water

86. Tata Steel Slide
Examples:
86
Hotel Room Key: Turn
off power when key is
removed
Elevator overload:
Don’t move if overloaded
Opening file cabinet: opening
of one drawer locks all the rest
to prevent file cabinet tripping

87. Tata Steel Slide
Case Study 1: Poka-Yoke on Punching Machine
87
Punching
Location
Metal
Clips
Problem Statement:
1. The problem in this case was missing metal
clips.
2. That component which was to be punch
sometimes sent further for punching
operation without conforming all metal Clips
are there on its place or not.
3. These were results in wastage of time which
indirectly affect productivity of the plant
About the case study:
This case study focuses on reducing PPM
(Parts per Million) to 0 PPM and the only way to
achieve 0 PPM is implementation of Poka-Yoke
(Control Type)

88. Tata Steel Slide 88
Case Study: Poka-Yoke on Punching Machine
Number of Defects/50 components (6 lots)
From chart 1, we can conclude that:
In each lot of 50 components, we found 2 to 3
components such that metal clips were missed
so if we calculate total PPM of the readings, we
get that it was too high which leads to wastage
of so much time.
Observation & Brainstorming:

89. Tata Steel Slide 89
Case Study: Poka-Yoke on Punching Machine
Problem Solution:
There is a very smart solution to this
problem which is expressed in circuit
diagram.
The main task we have to do is to stop the
air flow from the compressor to pneumatic
cylinder if any one of the metal clip is
missing.
Required components :
4 Proximity Sensor
Solenoid Valve
DCV (Pedal operated)
Double acting Cylinder
Electronic Control Panel (PLC)
Power Supply and Compressor
Selecting Solution & Implementation:

90. Tata Steel Slide 90
Case Study: Poka-Yoke on Punching Machine
Conclusion:
From this case study we have got positive output
which meets organizational requirement i.e.
1. Increased productivity
2. Achieved 0 PPM
3. Eliminated rework time
4. No chance for mistake
Number of Defects/50 components (6 lots)
Defects/50 components
Result & Conclusion:

91. Tata Steel Slide
EXAMPLES OF POKA YOKE IN REAL LIFE
91
Electronic equipment such as washing machines, ovens, etc don’t operate if the
doors are not closed or it stops working if the door remains open.
Type: Control type poka yoke, preventing process to operate till the necessary
conditions are met.
Spell checks in Ms word or other word processing software i.e. errors are
displayed with red/blue under lines.
Type: Warning type poka yoke
Sudden power off switches on workout equipment such as treadmills. Any
safety reasons making the runner to be able to shut down the equipment
instantly not leading to ay mishaps.
Type: Shut down type poka yoke

92. Tata Steel Slide 92
Elevator doors don’t close if any obstruction is sensed in between them, preventing
accidental squishing of people and objects.
Type: Control type poka yoke, not closing doors until it is clear.
Reverse gear lights that come up when the vehicle is put in reverse gear
indicating anyone behind the vehicle that the driver is reversing and they should
be careful.
Type: Warning type poka yoke
Circuit breakers in household electrical systems provided to avoid electrical
overloads by breaking the circuit when there’s sudden surge of electricity.
Type: Shut down type poka yoke
EXAMPLES OF POKA YOKE IN REAL LIFE

93. Tata Steel Slide
Examples: Implementation of PY in Manufacturing:
93
1. Fuel Tank Poka Yoke Assembly with flash
testing & leak testing
2. Carpet Gap Hider Poka Yoke Station:
The workstation is dedicated to apply the correct
lable to two products which are too similar to
each onther in size and in colour
3. Robotic Clipping & Welding System:
Mistake proofing fixture ensures proper clipping and
welding
4. Laser Drilling Process Cell
The fixture fixes the position of the product, ensuring
the laser drilling the correct size hole in the desired
position

94. Tata Steel Slide
Examples: Implementation of PY in Automotive industry
94
Two robots from each side of a car:
1.optical inspection,smart cameras
connected with a PC network for part
tracing,
2. multi-angle spectrophotometer for
colour inspection.
2. A preventing type PY,
-a Barrier at the street entrance,
which has the same dimension as
the bridge just ahead
You cannot take your car out of the parking
gear until the key is in the unlock position
and the brakes are activated. This prevents
the inadvertent error of allowing the car to
roll unintentionally.

95. Tata Steel Slide 95
Examples: Implementation of PY in Health Care Industry
A blood-lock, a single-use plastic lock allowing usage
only by the code placed on patient’s wristband,
Automatic wheelchair brakes, are examples of mistake
proofing devices in the healthcare process.

96. Tata Steel Slide
Examples: Implementation of PY in Software and service industry
96
1. Using a specific computer language and a unit test as a source
method, can prevent wrong coding or detect errors before they become
defects.
2. Bus station benches designed to prevent sleeping;

97. Tata Steel Slide
QUIZ Time:3
97
1. What are the types of Prevention based method of poka Yoke?
2. What are the types of Detection based method of poka Yoke?
3. Which type of poka-Yoke ensure 100% error free products?
4. SPN score 3 in Cost scoring is HIGH/LOW?
5. How many errors are there in GEM (General Error Mode)?

98. Tata Steel Slide
Total Quality Management 98
SMART/ Intelligent Poka-Yoke

99. Tata Steel Slide
Smart/ Intelligent Poka Yoke:
99
Intelligent Poka Yoke
01
Important opportunities are quickly identified with Intelligent poka yoke
Vital Steps for Optimization can be identified
02
Shorter observation periods with data represented graphically and pictorially are readily
available and hence only analysis must be done.
Reducing Observation Time
03
Intelligent Poka Yoke helps in experimenting rapidly on area of improvement without having
to wait as in the case of traditional TPM.
Rapid Experimentation
04
Larger sample data and lesser biased data results in more accuracy and better decision
making.
Eliminating Observer Effect

100. Tata Steel Slide 100
1. RFID antenna in a permanently installed coupling half (fixed half)
2. RFID transponder located in another coupling half (free coupling)
3. All important information (including transponder data storage) is transmitted contact-free by the
transponder from the free half to the fixed half
3. Equipped with such a RFID, an incorrect manual operation is virtually impossible and each
coupling process can be clearly documented and each filling operation controlled

101. Tata Steel Slide
Geo-Fencing : SMART Poka-Yoke
101

102. Tata Steel Slide
Light indicating despatch:
102

103. Tata Steel Slide
Barcode scan, cross check weight and approve:
103

104. Tata Steel Slide
IOT (Internet of Things) Based Poka-Yoke: Pump-House
104

105. Tata Steel Slide 105
1.The Rail Guided Vehicle System is based on intelligent, high-speed and floored rail
guided vehicles fitted for a wide range of load handling applications.
2.we may provide specific elements (i.e. fences, access controls or light barriers) that are
required to ensure a completely safe working environment for operators.
3.smooth and constant transportation is always guaranteed.

106. Tata Steel Slide
Total Quality Management 106
Poka-Yoke Qapsule
https://web.microsoftstream.com/video/765ac6cc-4976-4313-80bb-5ba2761597af

107. Tata Steel Slide
Total Quality Management 107

108. Tata Steel Slide

109. Tata Steel Slide
Implementation steps of Poka-Yoke:
109
Problem
Identification
Collecting
Customer
Complaint
Frequency of
complain and No
of defects to
capture
Workstation
Observation
Root Cause
analysis by Fish-
Bone Dia
Cause
classification: By
equipment,Materi
al, Method etc
Brainstorming
for Ideas
Causes to
discuss with all
employee
Capture various
solutions
Selection of
best Idea
Best solution to
select as per
Sr.Mgmt decision
Basis of
selection can be
cost, time,
simplicity,
adaptability and
operation ease
Implementation
Master Plan for
implementation
considering
material and
manpower
availability
Actual
implementation
need to check as
per plan
Implementation
Continuous
monitoring on
results and KPI
achievement
Project can be
closed

110. Tata Steel Slide
KAIZEN vs Poka-Yoke
110

111. Tata Steel Slide
POKA YOKE IDEAS
111
Poka yoke ideas are simple but creative in operation and generation.
According to Shingo, "Defects will never be reduced if the workers involved do not
modify operating methods when defects occur."
Following are some of the simple ideas (hints) to avoid mistakes: -
1) Using Shapes and Colours
2) Software Warnings and Reminders
3) Using Dialogue Boxes and Software Checks
4) Using Switches and Automatic Braking
5) Using Checklists
6) Visual Prevention Methods
7) Using Lights, Sounds, Signs and Barriers Etc

112. Tata Steel Slide
Cause-and-effect relationship (Shimbun, 1988):
112
DEFECTS
AND
THEIR
RELATIONSHIP
TO
HUMAN
ERROR
TYPES

113. Tata Steel Slide
ENHANCE
- Customer Satisfaction
REDUCE
- Reduce waste/scarp and avoid extra inventory
P
ACT
- Speed up productivity with Quality by taking action
COST
- Increase profit by avoiding continuous human error
POKA
YOKE
R
A
C
E
Need of Poka-Yoke ( why Poka-Yoke) : By RACE Model