2. Poka-yoke (ポカヨケ) is a Japanese term that means "mistake-
proofing". A poka-yoke is any mechanism in a lean
manufacturing process that helps an equipment operator avoid
(yokeru) mistakes (poka).
The concept was formalised, and the term adopted, by Shigeo
Shingo as part of the Toyota Production System. It was originally
described as baka-yoke, but as this means "fool-proofing" (or
"idiot-proofing") the name was changed to the milder poka-yoke.
Poka-Yoke example: Ethernet cable plug is designed to be
plugged in, in only one orientation.
3. Poka Yoke over Errors
Help operators avoid mistakes in their work caused by choosing
the wrong part, leaving out a part, installing a part backwards,
Involves the implementation of fail-safe ways methods that
detect or prevent human and machine error at or near the
Provides instant feedback and prevention of quality problems
4. Poka-Yoke as a...
Poka Yoke as Prevention Device: Examples: Part locators, Part
Poka Yoke as Detection Device: Examples: Vision system,
7. Why is it important ??
Helps people and processes
Refers to techniques that make it impossible to make
Helps drive defects out of products and processes and
substantially improve quality and reliability.
Used to fine tune improvements and process designs from six-
Use the ideas and methods in product and process design
which can eliminate both human and mechanical errors.
9. When to use it?
It is a technique, a tool that can be applied to any type of
process be it in manufacturing or the service industry.
Poka-yoke can be used wherever something can go wrong or
an error can be made.
Errors can be of any type –
• Processing Error
• Setup Error
• Missing Part
• Improper part/item
• Operations Error
• Measurement Error
10. How to use it?
Step by step process in applying Poka-yoke:
1. Identify the operation or process
2. Analyze the 5-Ws and understand the ways a process can fail.
3. Decide the right Poka-yoke approach, such as using a,
• Shut out Type: Preventing an error being made, or
• Attention Type: Highlighting that an error has been made.
4. Determine whether a
• Contact Method
• Constant Number or Counting Method
• Motion-Sequence Method
5. Trial the method and see if it works.
6. Train the operator, review performance and measure success.
11. Methods in Detail
Contact Methods:- The contact method identifies product defects
by testing the product's shape, size, color, or other physical
Constant Number or Counting Method:- The fixed-
value (or constant number) method alerts the operator if a
certain number of movements are not made.
Motion-Sequence Method:- The motion-step (or sequence)
method determines whether the prescribed steps of the process
have been followed.
12. Day to Day Examples of Poka-
File cabinets, opening one drawer locks all the rest, reducing the
chance of the file cabinet tipping.
Central locking in modern cars
Key locks in mobiles
Beeps in automobiles if key is left in ignition
13. Characteristics of Poka-Yoke devices
Simple and cheap
Part of the process, permitting 100% inspection
Placed close to where the mistakes occur, providing quick
Designed to stop a particular mistake
It will catch the errors before a defective part is manufactured
100% of the time.