Every methodology is imperfect until it is made perfect with the use of various tools and techniques. Achieving perfection is a never-ending process and by perfection we mean ‘zero defects.’ It is human behavior to make mistakes and in order to prevent those mistakes Shigeo Shingo adopted the poka-yoke technique in the Toyota Production System (TPS).
The term poka-yoke is derived from Japanese, which means ‘mistake proofing.’ In Lean Six Sigma, it is another helpful tool, which is used for continuous improvement.
Types of poka-yoke can include:
Defect Detection – The objective of adapting the poka-yoke technique is to eliminate any errors or mistakes, and to ensure that its recurrence is eradicated once and for all.
Defect Prevention – This is a technique which warns users about the occurrence of an error and predicts the possibility of a defect. This capability of a poka-yoke mechanism is very effective because a corrective action is implemented as soon as the error is detected and it doesn’t allow such errors to pass on to the next process.
A classic example of a poka-yoke device is electric sockets. The sockets are shaped in such a manner that when they are plugged in, it goes the right way. So, the question of making a mistake is ruled out in this case.
Having an error-free system is great and it has some additional benefits as well, such as:
- In Lean manufacturing, poka-yoke ensures that there is an absolute reduction in the number of defects, which would result in the production of high quality items.
- Eventually, safety measures are enhanced as there is a reduction in the rate of errors.
- There is improvement in the production process because of the non-value added element or waste removal.
- Poka-yoke devices are inexpensive and easy to implement.
- The ultimate advantage of installing these devices is the improvement in customer satisfaction through improved quality and delivery performance.