Poka-yoke in Japanese means ‘Mistake-proof’. A poka-yoke refers to any type of mechanism in Lean manufacture which helps an equipment operator to avoid (yokeru) mistakes (poka).
Poka-yoke eliminates product defects through prevention, correction, or spotting human errors as and when they occur. Shiego Shingo adopted this concept and made it a part of the production system of Toyota. Its original name of ‘Poka-yoke’ meaning “idiot-proofing” was then changed to the milder poka-yoke.
The implementation of poka-yoke can be done during any step in a manufacturing process when it is determined that something could go wrong or there is a possible error. For example, to ensure execution of required numbers of welds by the worker, a digital counter might be set to capture the count of spot welds.
Methods
The following three poka-yoke methods were recognized by Shiego Shingo with regard to detection and prevention of errors in production process:
- Contact method – Product defects are identified by testing the size, shape, color – the physical attributes of the product.
- Fixed Value (Constant Number) method – The operator is alerted if he is missing certain movement counts.
- Motion-Step (Sequence) method – Checks whether the process has followed the prescribed steps.
According to Shingo’s lexicon, a Warning poka-yoke alerts the operator when he is about to make mistakes. A Control poka-yoke prevents a device from making mistakes. In Shingo’s point of view, appropriate implementation of poka-yokes can result in quick identification of mistakes and elimination of defects. Since defects can be eliminated at source, cost efficiency is gained.
An effective process performance management includes proactive and reactive actions. For this, the senior management level should work with key executives in arriving at strategic decisions. In this manner, you can clearly define and achieve the goals which would be reliable, relevant, and timely. The process performance should be able to track its progress to reach the goal.
The process performance management should be:
- Formal – It should be well-defined and easy to understand
- Frequent – It should perform dissemination of information consistently
- Relevant – It should contain information and decision which is relevant to the department
- Reliable – It should not contain be imprecise
- Timely – It should ensure the process is ended at the planned time
- Tied to outcomes – The performance of everyone is in the path of achieving the goals.
- Feedback – It should provide continuous feedback about functioning of the process
- Group work – People from all the departments discuss changing processes and make day-to-day operational decisions.
Benefits of poka-yoke implementation in manufacturing
Technically, the poka-yoke is the best tool for manufacturing units. Because it has better mechanisms to prevent mistakes and defects processes. Here are some benefits of this method implementation in manufacturing:
- Reducing Scrap & Rework. When we implement mistake proofing technique in the processes, it may help to reduce the defects by its specific mechanisms. Hence, the possibility of scraping as well as rework will be significantly reduced.
- It saves overall production & resources time, as well as reduce unfair utilization of resources.
- Enhancement in productivity. If your manufacturing processes are streamlined, productivity will increase. The poka-yoke will be helpful to focus on value-added tasks, so that the processes will be organized in streamline.
- On implementation of poka-yoke, the manufacturing processes’ rework, inspection, and correction will be reduced. Hence, efficiency will be increased in line with implementation.
- It will be costs saving technique, the costs that are associated with reworks, re-inspection, material returns, etc.
- When the manufacturing facility deploys sensors detection devices at the machines may be safe for worker’s hand in case in wrong position, it may prevent from the accident.
In short, implementation of fool proofing may be a helpful technique to improve the product quality, efficiency, productivity as well increase the profitability.