Poka-Yoke refers to mistake-proofing methods that eliminate or reduce errors in manufacturing processes. It aims to eliminate the cause of errors at the source, detect errors as they are made, or detect errors soon after before the next step. While errors were once seen as inevitable, the document argues they can be eliminated through proper training, support systems, and implementing poka-yoke devices that build quality checks into the production process. 100% inspection is preferable to sampling inspection as it ensures no defective products reach customers.

2. What is Poka-Yoke?
• This is known as ‘MISTAKE-PROOFING’
• From Japanese:
• Yokeru (avoid)
• Poka (inadvertent errors)

3. What Does Poka-Yoke Do?
• Eliminates the cause of an error at the
source;
• Detects an error as it is being made;
• Detects an error soon after it has been
made but before it reaches the next
operation.

4. Are Errors Unavoidable?
• There are two approaches to dealing with
errors:
• 1. ERRORS ARE INEVITABLE!
• 2. ERRORS CAN BE ELIMINATED!

5. 1. Errors Are Inevitable
• People always make mistakes.
• While we accept the mistakes as natural, we
blame the people who make them.
• With this attitude, we are likely to overlook
defects as they occur in production.
• They may be detected at final inspection, or
worse still, by the customer.

6. 2. Errors Can Be Eliminated
• Any kind of mistake people make can be
reduced or even eliminated.
• People make fewer mistakes if they are
supported by proper training and by a
production system based on the principle
that errors can be avoided.

7. Inspection
• One method of detecting errors is
inspection.
• There are two major types of inspection.
• 1. SAMPLING INSPECTION.
• 2. 100% INSPECTION.

8. 1.Sampling Inspection
• In some factories, the attitude is:
“It may take all day to inspect all product”.
• “There may be a few defects, but sampling is the most
practical way to check”.
Sampling Inspection - Reflection
• Think about sampling.
• With sampling, there is a chance that an error may go
undetected.
• Even if 1 part in 1000 is defective, the customer who
buys that part has a 100% defective product!

9. Sampling Inspection - Reflection
• Think about sampling.
• With sampling, there is a chance that an error may go
undetected.
• Even if 1 part in 1000 is defective, the customer who
buys that part has a 100% defective product!

10. SAMPLING INSPECTION MAKES SENSE ONLY
FROM THE MANUFACTURER’S VIEW, NOT
FROM THE CUSTOMER’S!
Sampling Inspection - Reflection

11. 2. 100% Inspection
• In the best factories, the attitude is:
• “We won’t tolerate a single defect!”
• “We will organize production so that 100%
of the product can be easily inspected”.
• “That makes the most sense”.

14. The User is Best Inspector

16. Two Strategies for Zero Defects
1. DON’T MAKE IT!
1. Don’t Make It!
 Don’t make product you don’t need.
 The more you make, the greater the opportunity for defects.
 Follow ‘just-in-time’ principles by only making what is
needed, when it is needed in the amount needed.

17. Two Strategies for Zero Defects
2. Build Safeguards
The user is an expert in finding defects.
Therefore build safeguards into the production
process.
Quality can be built into products by implementation
of Poka-Yoke.

18. Poka-Yoke Devices
Human errors are usually inadvertent.
Poka-yoke devices help us avoid
defects, even when inadvertent errors are
made.
Poka-yoke helps build quality into
processes.

19. Poka-Yoke Devices
– Error Detection and Alarms

20. Poka-Yoke Devices
– Checklists

21. Poka-Yoke Example
It is possible to mount the blank the
wrong way onto the pierce tool.
As the blank can fit the pierce tool in
many ways, how can this be prevented?

22. Poka-Yoke Example