mistake proofing for web1
TRANSCRIPT
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Mistake Proofing For Zero Defect Quality
Poka-Yoke
A Strategy For Performance Excellence
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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
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
How to Poka-Yoke?
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Session: 1
Paradigm Shift For Zero Errors
Paradigm Shift For Zero Error
Dr. Albert Einstein said:
“The significant problems we face cannot be solved by the same level of thinking that created them”
GET
DO
SEE
Principles
Shift in Paradigm
Reduction in
defects/rejects
Improved
Quality
Satisfied Customer
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Do “Poka Yoke”
SEE
DO
GET
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
Zero Defect Quality (This
method is even better
than Six Sigma)
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
Managing through Kaizen Paradigm
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New Paradigms
How Should Kaizen Mind Work?
- The existing operation always has a lot of room for improvement
- The existing facilities and methods can always be improved by efforts
- The accumulation of improvements makes a big difference
It is a positive attitude
through…….
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How Many Legs Does Elephant Has?
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Session: 2
Introduction of Poka-Yoke
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”
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Characteristics of Poka-Yoke
- They are part of the processes
- They are placed close to where the mistakes occur
- Once put in place, they require minimal supervision
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- Simple & Inexpensive
- 100% Inspection
- Immediate Feedback
Other Characteristics:
These three characteristics are also known as 3 Qualifiers:
Purpose of Poka-Yoke
- Utilize Mistake proofing from design phase to final phase
- Utilize Mistake proofing as a preventive tool
- Apply Poke-Yoke methods as control on identified issues
- Reduce or eliminate process errors / defects from occuring
- Increased level of Self-esteem amongst employees
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By the end of the module, participants will be able to:
Why is Mistake Proofing Important?
- Improved Quality & Customer satisfaction
- Prevents error / defect occurrence
- Makes it difficult to perform the task in a wrong way
- If defects occur; ensures corrective action
- Requires little or No formal training
- Cost effective
- Easy to implement
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Session: 3
Process Waste Management
Value adding
Optimize
Necessary but
not value adding
Minimize
Non value adding
WASTE
5%
35%
60%
Primary focus of “traditional”
efficiency improvements
Primary focus of
LEAN improvements
Attack the NVA first and reduce
the NVA through further
improve & eventually eliminate
it completely. A process in
general has around 95% Waste
in the form of NVA
Lean Eliminates Non-Value Adding Activities
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“Every activity that we do costs something without adding
value to the product”.
Our objective
Maximize Value adding activities
Minimize Non-value adding activities
What is Waste?
8 Types of Wastes
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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
Elimination of Wastes and Continuous Improvement
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The Approach
• Lean
• KAIZEN
• Elimination of Wastes
• Continuous Improvement
• Standard Work
• Process Control
The Means
• Poka-Yoke• One piece flow
• SMED
• Visual Controls
• Workplace Organization
• Inventory Management System - Kanban
The Strategy
• Quality Right the First Time
• Reduce Costs
• Reduce lead time
• Including Safety
• Total Productive
Maintenance
• Value Stream Mapping
Vision For Creating Performance Excellence
- Working in a condition of zero defect
- Employee Involvement is very important
- Review every process to make it error proofed
- Everyone is accountable for Performance Excellence
- Continual improvement is a way of life
- All kinds of defects, rejects, rework can be avoided
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Session: 4
Zero Defect Quality
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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!
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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!
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Cost of Defects?
Does it cost more to make processes better? NO
Making processes better leads to reduced
Rework
Scrap
Warranty costs
Inspection costs
12%
4%
7%
11%
There is always a cost associated with manufacturing defects!
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Session: 5
3 Qualifiers of Poka-Yoke
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3 Qualifiers of Poka-Yoke
1) Simple & Inexpensive
Poka-yoke devices must be simple in implementation and usage.
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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.
Closed
Cabinet
Transparent
Cabinet
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2) 100% Inspection
Only Point of Origin Inspection actually eliminates defects, rejects, rework, etc.
“Focus on prevention, not detection”
• Catches errors
• Gives feedback before processing
• No risk of making more defective product Detect Error
Feedback / Corrective Action
Process with Zero Defects
By combining Check and Do in
the ZDQ approach
May include Switches that detect
miss-fed parts
- Pins that prevent miss-feeding
- Warning lights
- Sound signals
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ZDQ / Check & Do / Point of Origin Inspection
- Check for optimum process conditions before processing is done and errors can be made
- Instant feedback
- Corrections made before defects occur
- Does not rely on sampling
- Prevents defects
- Does not assume defects will statistically occur
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
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100% Inspection
Count F’s
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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.
Count:
36
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Answer
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100% Inspection
- Check occurs immediately after the process
- Can be an operator check at the process
- Not 100% effective, will not eliminate all defects
- Effective in preventing defects from being passed to next process
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
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3) Immediate Feedback
ZDQ sends the operator a signal and alarms the person that an error has happened!
ZDQ Inspections = Immediate Feedback
The third qualifier provides immediate feedback, whereas traditional method provides feedback after the whole process is finished
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How to Poka-Yoke?
(Implementation)
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Session: 6
Poka-Yoke examples From Daily Life
Poka-Yoke Example
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This Stove burner turns off automatically when pot
or pan is removed
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
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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
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Session: 7
Poka-Yoke Systems
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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
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1) Control System
- Takes human element out of the equation; does not depend on an operator or assembler
- Has a high capability of achieving zero defects
- Machine stops when an irregularity is detected (Overheating M/C)
“There must have
been an error
detected; the
machine shut down
by itself”
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2) Warning System
- Sometimes an automatic shut off system is not an option
- A warning or alarm system can be used to get an operators attention
- Color coding is also an effective non-automatic option
BEEP!
BEEP!
BEEP!
“I’m glad the
alarm went ON
now I’m not
making defects!”
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Session: 8
Method of Poka-Yoke
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Methods for Using Poka-Yoke
Poka-yoke systems consist of threeprimary 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
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1) Contact Method
“A contact method functions by detecting whether a sensing
device makes contact with a part or object within the process”
Missing cylinder;piston fully
extended alarm sounds
Contact Method using limit
switches identifies missing
cylinder.
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
processCannot proceed
to next step.
Cylinder present
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Physical Contact Devices
Limit Switches Toggle Switches
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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
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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
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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
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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!”
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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
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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
Indicator BoardMachine
Types of Sensing Devices
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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
A) Physical Contact Sensors
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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.
B) Energy Sensors
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“These devices work by using energy to detect whether or not any defect has occurred”
Fiber optic
Photoelectric
Vibration
C) Warning Sensors
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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
3 Rules of Poka-Yoke
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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!
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Session: 9
Types of Poka-Yoke
1) Judgement Inspection
In Judgment inspection, we sorted the defects out
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2) Informative Inspection
In Informative inspection, we do “Successive checks”and “Self-checks”
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3) Source Inspection
Detects mistakes before they
become defects
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Transformation = Quality production right the first time
Inspection….eliminated ???
Transport
Storage
Delay/wait
Dedicated lines
One piece flow
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Session: 10
Principles of Poka-Yoke
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
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• 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
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Principles of Poka-Yoke
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Session: 11
100-1000-10000 Rule
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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
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
Cost
How do defects impact cost?
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Operation ASource
In-process Inspection
Operation BDownstream
Final Inspection
Customer
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
Downstream Process
Incremental Cost
Golden Rule
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Inspection Detection Correction Preventionis is leads to
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Session: 12
Types of Human Mistakes
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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
Types of Human Mistakes
- Forgetfulness
- Misunderstanding
- Wrong identification
- Lack of experience
- Willful (ignoring rules or procedure)
- Inadvertent or sloppiness
- Slowliness
- Lack of standardization
- Surprise (unexpected machine operation, etc.)
- Intentional (sabotage)
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To prevent mistakes, install error proofing devices
Checklists
Dowel and locating pins
Error & alarm detectors
Limit or touch switches
Detectors, readers, meters, counters
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To Prevent Mistakes To occur
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POKA-YOKE SHEET COMPANY NAME
Problem:
Prevent Error
Shutdown
Solution:
Control
Key Improvement:
Detect Error Alarm
Before After
Picture Picture
Poka-Yoke Format
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