One of the important parameters of lean manufacturing is customer satisfaction and in today’s competitive environment and urgencies of project majority of chances to bypass quality as well as safety during production or service activity. The solution to improve both parameters applies Poka-yoke or error-proofing techniques to your organization to reduce or remove repetitive errors.
Poka-yoke helps to improve Quality errors as well as improve bad safety practices, Where kaizen helps to small – small improvements on day to day basis & 6 ‘S’ Methodology helps to systematically arrange the workplace.
What do you learn from this article?
- Basic History.
- What is poka-yoke?
- practical implementation Steps for poka-yoke.
- Practical examples of poka-yoke.
- Approaches of poka-yoke.
- Types of poka-yoke.
- Implement poka-yoke.
- 6 key principles to implement poka-yoke.
History of poka-yoke
Developed By- Shigeo Shingo in 1960.
First implemented by – the Toyota production system.
What is poka-yoke?
Poka-yoke is a Japanese word, the meaning of poka-yoke is error proofing or mistake proofing. In worldwide industries using poka-yoke to minimize error during the production process & safety perspectives. In short, Poka-yoke helps to produce defect-free products & improve more reliability of products as well as processes.
What are the examples of poka-yoke?
- Pen drive & USB socket on laptop or desktop.
- Mobile charger & socket – directly fitted without error.
- Water bottle with its cap design.
- Pen with its refill design.
What are the approaches of poka-yoke?
- Control Approach: – In the control approach when an error occurs in the system, immediately processes stop at that point in time. Qualified staff checks what is the error & they start the process again after the clear error.
For example – in the food manufacturing industry food products pass on a conveyor belt & metal detector is attached for indication purpose, when metal detect on the conveyor belt of the food products line immediately stop.
- Warning Approach: – In the warning approach when an error occurs in the system Poka yoke gives a warning but they didn’t stop any activity, basically, poka-yoke gives a signal to passing errors & qualified staff immediately take action.
Example: – In the food industry, measure oil temperature periodically based on the temperature measuring instrument. It is attached to an oil tank so this instrument is a poka-yoke they give a warning of the temperature rising but could not stop the burner – that is warning poka-yoke.
Types of poka-yoke
- Contact type:- the contact type poka-yoke is contact with two different segments like a pen drive & USB socket, writing pen & cap.
- Fixed value type:- fixed value type poka-yoke is one part of the two segments is partially fixed – to develop the design of the fixed part in such a way that it gives signals for another part is missing or not. Ex.- Eggs & Its tray.
- Motion step type: – motion step type poka-yoke is ensure that the operator going to follow the correct number of steps, like – the seat belt of the car.
Review below attached poka yoke format for record improvement opportunities.
The poka-yoke format fill-up guide is similar to the kaizen format fill-up guide, review the kaizen article.
What are the 6 key principles of poka-yoke?
After a basic understanding of the poka-yoke background, approaches, types & implementation steps, now very important things to know is what is the reason behind the implementation of poka-yoke. The answer is simple to remove or minimize the error during processes right? The key important point during poka-yoke implementation is we deeply understand errors as well as the root cause behind errors. Otherwise, we implement error-proofing techniques but do not impact on final results.
Now we going to understand each basic principle of poka-yoke implementation.
1. Elimination
The elimination principle uses to design processes in such a way as to eliminate errors from processes or products. Suppose your design manufacturing process & outcomes found during inspection is not satisfied with customer requirement. Now in elimination principle says that you identify the error that comes from which process & design this process in another way. There will be major changes to errors that will not come in the future with similar principles.
In the elimination principle, there is no chance of repetitive error.
2. Prevention
During poka-yoke, design prevention principles suggest modifying the processes, not re-design processes. Process modification is done based on the trial & error method. For example, if you found an error during processes & you want to implement poka-yoke with a prevention approach. Now the modify process & check the comparison of the previous & modified process results.
In prevention, principles attach some limit switches and sensors to stop the process. In this case, minimum chances of mistakes during processes performed.
Example: – In a manual drilling machine operator’s task is to drill a 10 Nos hole in a plate. During quality, the check inspector found an error in interchangeability. Now we redesign the process & drilling tool guiding the jig to be attached to the drilling process. Outcomes to eliminate error from processes.
3. Replacement
Replacement principles say that without changing process design as well as without modifying the process, plan to minimize error. For example, initially, we work on manual processes & in the modified version we install semi-automatic machines to minimize human error.
Example: – Installation of semi-automatic, fully-automatic, robotics in processes to minimize manual work & manual work transferable to human error.
4. Facilitation
Facilitation is low-cost & widely used principle. To minimize errors with the help of visual control, and color coding, the attached checklist for pending activities is easy identification.
Examples: – During the 6 ‘S’ Implementation workstation wise items are color-coded due to no chance of item mismatch.
5. Detection
Detection principles are used to detect errors before manufacturing. Attach some signal or sensor to the machine or workplace to give the alarming signal for the process not performing as per specification.
Example: – Andon signal used to detect errors from processes. No punch counting mechanism installs in the press machine to minimize error.
6. Mitigation
The main key objective of the mitigation principle is to minimize the effect of the error. This principle says if your processes outcomes in product rejection, then put extra design margin provide to products so at least transferable zone into product rework.
Some of the safety sensors suggest that the process is going to a critical situation that follows the mitigation principle.