Poka Yoke – eliminate mistakes in company
The name Poka Yoke comes from the Japanese poka, meaning mistakes, and yokeru, meaning prevention. It is one of the techniques of lean, or more precisely, continuous improvement, and means preventing or signaling errors created by inattention and lack of concentration. Poka Yoke also means devices, lean tools or software that prevent defective or substandard products from being passed on to subsequent production stages.
1. Poka Yoke Method
Poka Yoke are divided according to their functions and the methods used. For adjusting devices, control and warning methods are used. For setting devices, contact and necessary step or set value methods are used.
- The control and warning method involves stopping the machine or equipment when a product defect occurs or is detected, and restarting only after the defective product is removed or repaired. Built-in control functions allow the machine to be stopped when a fault or defect is detected. Light effects or sound signals warn the operator that a defect has occurred. Unfortunately, the operator’s failure to react allows production to continue with defects, which is something we want to avoid.
- A contact method possible to stop a defect, such as using a forced hole arrangement that determines how the part is positioned and does not allow other than the required one. Or optical cameras that check the color of the product, the shape or compare the tested part with a standard. They detect nonconformity, give a signal and stop the process at the same time.
- The necessary step method involves detecting an error created by not fulfilling the sequence of actions/steps, or keeping the time set for each operation.
- The set-value method is the checking of a certain number of items or movements according to set standards. Movement counters, for example, are used for this.
2. Examples of Poka Yoke applications
Use of pick-to-light devices during order picking. These devices, through light signals, indicate to operators the type of product, the place of picking and the quantity required for picking, thus eliminating human errors that occur during the picking process (incomplete orders, the wrong quantity or the wrong article).
Warehouse software used to determine the sequence of tasks. The system sends information about the sequence of activities to the device, the employee, after receiving the information/command, confirms the task to receive the next command. In this way, employees perform their duties faster, more efficiently and without making mistakes, according to the concept of Lean Management.
Security fences to protect the working area of automatic equipment from unauthorized persons and accidents. The emergency stop system of the equipment will bring it to a halt if it enters this zone, for example, by a worker’s mistake.
Examples of Poka Yoke devices can be seen not only in the manufacturing company, but also in the activities that accompany us every day. When withdrawing money at an ATM, we have an exact time to collect the bills. In addition, when wishing to use an ATM, we can only place the payment card in it in one position. The ATM will also not dispense money unless the card is removed from it beforehand.
The elevator is also an example of a Poka Yoke device, as it is equipped with sensors that prevent the doors from closing when there is a person or object between them eliminating the occurrence of accidents.
3. Why use Poka Yoke in a company?
- Eliminate human and system errors.
- Reducing the number of defective products, and thus fewer complaints.
- More effective process control.
- Improving the quality of products, services, and processes.
- Reduced process execution time, resulting in increased production capacity.
- Reducing repair costs.
Implementing Poka Yoke solutions therefore results in more efficient production processes. Fewer defects, defects and errors of various kinds mean more profit and satisfaction for both employees and customers. Lean implementations bring great benefits, see for yourself.
We recommend using poka yoke at the product design and process design stages. The investment of time in preventing errors will pay off at the startup stage.