Poka Yoke / Error Proofing / Mistake Proofing

Poka Yoke / Error Proofing / Mistake Proofing

What is Poka Yoke?

 - Poka Yoke is a japanese term in that "Poka" means mistake and "Yoke" means to avoid.
 - It is a system or mechanism that helps to avoid mistakes.
 - When any defective product occur, we can detect it, eliminate it or correct it by using Poka Yoke.
 - This concept was used in the 1960s by Shigeo Shingo as a part of TPS (Toyota Production System).

History of Poka Yoke

 - Poka Yoke was first used in Japan in 1960s by Shigeo Shingo engineer in Toyota.
 - The initial term was Baka Yoke means " Fool Proof", but due to term's offensive connotation it was changed to Poka Yoke.
 - Poka Yoke helps to prevent defects from occuring in the first place.

Examples of Poka Yoke

 - Airbags quickly deflate after an accident to prevent injury.
 - When you closed washing machine door then only washing machine start.
 - USB cable enter facing one side only.
 - Machine automatically stopped when any object comes under sensor.
Examples of Poka Yoke


Steps to Implement Poka Yoke

1. Problem Identification
2. Set Priority
3. Identify root cause
4. Find and Implement solutions
5. Measure the result

Poka Yoke Techniques

Poka Yoke Techniques

1. Elimination

 - In this technique we have to eliminate the steps which are responsible for mistake.
 - Remove Non value added activities and redesign the product also modified the process.

2. Replacement

 - When elimination is not possible then replace the step with more reliable mistake proof one.
 - Do RPA(Robotic Process Automation) for repetitive activities.
 - E.g Welding robots

3. Prevention

 - Third technique is prevention means change product or process to prevent mistake.
 - It is a physical barrier to prevent undesired acton.
 - E.g No go and Go gauges

4. Facilitation

 - Facilitation technique help someone to take correct decision.
 - Control the process or product by visual controls like colour coding, visual instructions, sign boards etc.

5. Detection

 - Detection means detect and identify the defective part or wrong process immediately after it happens.
 -Sensors, Light sensors, Proximity sensors, limit switch etc are used for detection.

6. Mitigation

 - If all above five  techniques are not possible then last option is mitigation.
 - Mitigation means minimize the effect of failures. This technique is used when the mistake or error cannot be eliminated.

Types of Poka Yoke

Types of Poka Yoke

1. Contact Method

 - Locating pins, limit switches and proximity switches are used to in contact method.
 - It is a method to detect the defects like shape, size, colour etc.

2. Fixed Value Method

 - This method is used when same activity is repeated several times.
 - It is method that uses physical and visual methods to identify all the components are available in right quantities.
 - Counters can be used for this method.

3. Sequence Method

 - This method ensure that correct number of steps are followed before moving to the next step.
 - This method not allowing the mistake to be made in the first place.

Benefits of Poka Yoke

 - Remove defects easily from source
 - Faster defect correction and detection
 - Improve workers safety
 - Immediate action when problem occur
 - Reduce number of rejections

3 simpl rules for error proofing system
Poka Yoke / Error Proofing / Mistake Proofing


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