1. POKA-YOKE, AS A QUALITY IMPROVEMENT TOOL

2. INTRODUCTION What is a Poka- yoke?
Shigeo shingo defined poka-yoke as POKA- ‘Inadvertent mistake that anyone can make’ and YOKE- ‘To prevent or proof’
Poka-yoke is a tool to have “zero defects” and even reduce or eliminate quality control.
Poka-yoke is a Japanese name for “fool-proofing”.
Poke-yoke represents the intelligence of the operator by excluding repetitive actions that require a thinking process.
By this method the operator is more free creative thinking and added value activities.

3. BACKGROUND & HISTORY
Shingo suggested a solution that became the first poka yoke device:
In the old method, a worker began by taking two springs out of a large parts box and then assembled a switch.
In the new approach, a small dish is placed in front of the parts box and the worker's first task is to take two springs out of the box and place them on the dish. Then the worker assembles the switch. If any spring remains on the dish, then the worker knows that he or she has forgotten to insert it.
The new procedure completely eliminated the problem of the missing springs.

4. MISTAKE PROOFING
Mistake-Proofing a product's design and its manufacturing process is a key element of design for manufacturability / assembly (DFM/A)
Mistake proofing is also a key element of improving product quality and reliability
FACTORS CONTRIBUTING TO MISTAKE PROOFING:
Attention
Perception
Memory
Logical reasoning

5. PRINCIPLES OF MISTAKE-PROOFING
There are six mistake-proofing principles or methods.
Elimination seeks to eliminate the possibility of error by redesigning the product or process so that the task or part is no longer necessary.
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.
Facilitation employs techniques and combining steps to make work easier to perform.
Detection involves identifying an error before further processing occurs so that the user can quickly correct the problem.
Mitigation seeks to minimize the effects of errors.

6. 2-STATUS & 3-FUNCTIONS OF POKA-YOKE
POKA-YOKE HAS 2 STATUS AND 3 FUNCTIONS:
Status:
1.The fault will happen or
2.The fault has happened
Functions:
1.Stop
2.Check or
3.Alarm

7. THREE STRATEGIES FOR ZERO DEFECT
Only make the product when required!

8. THREE STRATEGIES FOR ZERO DEFECT
Make the product so it can not be used for anything else.

9. THREE STRATEGIES FOR ZERO DEFECT
If the product is ready use it immediately.

10. POKA-YOKE CLASSIFICATION
Based on what is fail-safed poka-yoke is classified into the following types:
Server Poka-Yokes
Task
Treatment
Tangibles
Customer Poka-Yokes
Preparation
Encounter
Resolution

11. PROVIDER(SERVER) ERRORS
Task Errors
Doing the work incorrectly
Doing work not requested
Doing work in the wrong order
Doing work too slowly
Treatment Errors
Not acknowledging the customer
Not listening to the customer
Not reacting appropriately to the customer
Tangible Errors
Failure to clean facilities
Failure to control noise

12. CUSTOMER ERRORS Preparation Errors
Failure to bring necessary materials to the encounter
Failure to understand role in the service transaction
Failure to engage the correct service
Encounter Errors
Failure to remember steps in the service process
Failure to follow system flow
Failure to specify desires sufficiently
Failure to follow instructions
Resolution Errors
Failure to signal service failures
Failure to learn from experience
Failure to adjust expectations appropriately

13. SEVEN STEPS TO POKA-YOKE ATTAINMENT
Quality Processes
Utilize a team environment
Elimination of Errors
Eliminate the “Root Cause” of The Errors
Do It Right The First Time
Eliminate Non-Value Added Decisions
Implement an Incremental Continual Improvement Approach

14. POKA-YOKE APPROACH
Poke-yoke and Point of Origin Inspections( Proactive Approach):
A fully implemented ZERO DEFECT QUALITY system requires Poka-Yoke usage at or before the inspection points during the process.
Poka-yoke will catch the errors before a defective part is manufactured 100% of the time.
Poka-yoke and Informative Inspection( Reactive Approach):
Check occurs immediately after the process.
Can be an operator check at the process or successive check at the next process.
Not 100% effective, will not eliminate all defects.
Effective in preventing defects from being passed to next process.

15. POKA-YOKE SYSTEMS GOVERN THE PROCESS
Two Poka-Yoke System approaches are utilized in manufacturing which lead to successful ZERO DEFECT QUALITY:
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.

16. 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.
“There must have
been an error detected,
so the machine
shut down by itself”

17. WARNING SYSTEMS
Sometimes an automatic shut off system is not an option.
A warning or alarm system can be used to get an operators attention.
Below left is an example of an alarm system using dials, lights and sounds to bring attention to the problem.
Color coding is also an effective non-automatic option
I’m glad that the
alarm went off,
now, i’m not
making defects

18. TEN TYPES OF HUMAN MISTAKES
Forgetfulness
Mis-understanding
Wrong identification
Lack of experience
Willful (ignoring rules or procedure)
Inadvertent or sloppiness
Slowliness
Lack of standardization
Surprise (unexpected machine operation, etc.)
Intentional (sabotage)

19. POKA-YOKE DEVICES
Poka yoke is implemented by using simple objects like fixtures, jigs, warning devices and the like to prevent people from committing mistakes, even if they try to!.
The main feature of poka-yoke devices is their exceptional suitability for reducing or eliminating defects through effective feedback and instantaneous corrective action.
These devices are capable of being used all the time by all workers; simple and usually installed with low implementation cost.
Poka-yoke devices help eliminate errors and defects by giving machines the “intelligence” to stop and signal when a error occurs.
Poka-yoke devices stop machines and alert workers when a problem exists.

20. The Three Levels of Poka-Yoke:
There are three levels at which your company can effect poka-yoke:
Eliminating errors defects and losses at the source or prevention of a mistake from being committed..
Detection of a loss or mistakes it occurs,allowing correction before it becomes a problem.
Detection of a loss or mistakes after it has occurred,just in time before it blows up into a major issue(least effective).
Of course, preventing a defect or loss in the first place is the most effective form of poka-yoke.
However, devices for catching defects or losses and immediately stopping the action are also valuable.
Eg.,warning lights in your automobile that alert you to a problem such as low oil or a nearly empty fuel tank before the problem affects the operation of your vehicle.

21. EXAMPLES OF POKA-YOKE PRODUCTS

22. EXAMPLES OF POKA-YOKE

23. IMPLEMENTATION IN MANUFACTURING
Poka-yoke can be implemented at any step of a manufacturing process where something can go wrong or an error can be made.
Shigeo Shingo recognized three types of poka-yoke for detecting and preventing errors in a mass production system:
The contact method identifies product defects by testing the product's shape, size, color, or other physical attributes.
The fixed-value (or constant number) method alerts the operator if a certain number of movements are not made.
The motion-step (or sequence) method determines whether the prescribed steps of the proce ss have been followed.

24. IMPROVEMENT PRINCIPLES FOR POKA-YOKE
Stop by doing wrong, do it right. Do it now!
Build quality in the process.
No excuses.
If your poka yoke idea has better than 50% chance to succeed…Do it!
Do it now….improve later!
Team work
Why, why, why, why, why ?????

25. ADVANTAGES
They are simple and cheap. If they are too complicated or expensive, their use will not be cost-effective.
They are part of the process, implementing what Shingo calls "100%" inspection.
They are placed close to where the mistakes occur, providing quick feedback to the workers so that the mistakes can be corrected.
Judged by these criteria, the "small dish" solution to the missing-spring problem is an excellent poka-yoke device:
It was simple.
It was cheap, involving only the cost of a small dish.
It provided immediate feedback about the quality of the work; corrections could be made on the spot.

26. THANK YOU