2. Lets Understand Cost Of Defect
Presently cost of poor quality is on very high. Company miserably failed
to increase their profit. Each loss can be converted in to Profit
• Cost of internal rejection
• Cost of External rejection
• Cost of complaint
• Cost off Warranty claims
• Cost of inspection
3. What is Poka Yoke
• Error proofing is a structured approach to Ensuring Quality all the
way through your work processes.
• enables you to Improve Your production or Business Processes to
Prevent Specific Error / defects
• Focus of error proofing is Not on identifying and Counting Defect
Elimination of their cause
• Error And Defect are Different.
• Poka -Yoke will not prevent Defect But Prevent Error.
4. • The success of poka-yoke is to provide some intervention device or
procedure to catch the mistake before it is translated into nonconforming
• In a “fat” system, any defects that are found can simply be discarded while
operations continue. These defects are later counted, and if their numbers
are high enough, root-cause analysis is done to prevent their recurrence.
But in a lean enterprise, which concentrates on producing smaller batch
sizes and producing to order versus adding to inventory, a single defect can
significantly impact performance levels. When a defect occurs in a lean
enterprise, operations must stop while immediate action is taken to resolve
the situation. Obviously, such pauses in operations can be costly if defects
occur often. Therefore, it is important to prevent defects before they can
What is Poka Yoke
5. Elements of Error Proofing
9. Ways to Mistake Proofing
Old Method New Method
Reprimand Worker Remove Opportunity of Error
- Make Wrong action more difficult
Retrain worker If you can not remove opportunity of Error
- Make it easier to remove error
Tell them to Pay them attention
10. First Poka Yoke
• Shingo Suggested – A solution that become the first Poka Yoke
• In the old Method a worker began by taking two springs, out of a
large parts box and then assembled a switch.
• Problem – Some time worker Failed to put 2 springs in the switches
• New Approach – New Approach, two spring will be lifted and kept in
empty plate, After assembly if any spring remain there, worker will
came to know the thing.
11. Common Sources of Errors
Process Step Transportation Material Machines
High Volume Adjustment Mixed Part
12. Poka – Review of Human Error
• Mistake prevention in the work environment.
• Mistake detection (Shingo’s informative inspection).
• Mistake prevention (Shingo’s source inspection).
• Preventing the influence of mistakes.
• Mistake Prevention in the Work Environment
14. Poka Yoke Principle
Elimination – This seeks to eliminate the possibility of Mistake by
redesigning the product or process so that the task or part is no longer
Example : Product simplification or part consolidation that avoids
a part defect or assembly Mistake in the first place
Replacement – Substitute a more reliable process to improve
Example : Use of robotics or automation that prevents a manual
assembly Mistake, automatic dispensers or applicators to ensure the
correct amount of material such as an adhesive is applied.
15. Prevention – Design the product or process so that it is impossible to make a
mistakes at all.
Example – Limit switches to assure a part correctly placed before
process is performed; part features that only allow assembly the
correct way, unique connectors to avoid misconnecting wire
harnesses or cables, part symmetry that avoids incorrect
Facilitation – Employ techniques and combining steps to make work easier
Example – visual controls including colour coding, marketing or
labeling parts to facilitate correct assembly ; exaggerated asymmetry
to facilitate correct orientation of parts; a staging tray that provides a
visual control that all parts were assembled, locating features on
Poka Yoke Principle
17. Detection – Identify a mistake before further processing so that the user can
quickly correct the problem.
Examples – sensors in the production process to identify when parts
are incorrectly assembled built-in self-test (BIST) capabilities in products
Mitigation – Minimizing the effects of Mistakes.
Examples – fuses to prevent overloading circuits resulting from
shorts, products designed with low – cost, simpler rework procedures
when a Mistake is discovered, extra design margin or redundancy in
products to compensate for the effects of Mistakes.
Poka Yoke Principle