Poka-Yoke
What is it?
Poka-yoke is a device or solution designed to prevent errors or make them immediately obvious when they occur. In Lean Production, Poka-yoke is an error-proofing tool that builds quality into the process, preventing defects from moving downstream.
How can I help?
Implementing Poka-Yoke reduces operational errors, defects, and rework, lowering non-quality costs and increasing process reliability. It is particularly effective for repetitive tasks and critical operations: a simple design improvement or a sensor can prevent incorrect assembly or immediately signal an out-of-tolerance measurement. Integrated with Standard Work and Jidoka, it helps make problems visible and speeds up corrective actions.
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Types Poka-Yoke and practical examples in production and in offices
Designed by Shigeo Shingo within the Toyota Production System, the Poka-Yoke (literally “avoiding unintentional mistakes”) makes a distinction between prevention (physically prevent the error from occurring) and immediate detection (lock the cycle or alert the operator as soon as an anomaly occurs). In the plant, it is divided into three main methods:
- Contact method (shape, size or asymmetry): Spines, connectors or asymmetrical mounting plates that allow the part to be inserted in a correct direction, making reverse mounting impossible.
- Fixed value method (counting): pre-shaped trays (kitting) or screw drivers stuck to the PLC that count the exact number of tightening operations performed and do not release the part until all the screws have been tightened to the prescribed torque.
- Method of movement-step (sequence): Photoelectric barriers on component containers or guided digital checklists (also in office processes and ERP order entry) that prevent moving on to the next step if the previous verification has not been completed.
Frequently asked questions Poka-Yoke (FAQ)
What is a system Poka-Yoke in Lean Production?
It Poka-Yoke is a technical or procedural device that is error-proof (error-proofing) designed to prevent human distraction from turning into a product or process defect, eliminating late quality checks at the end of the line.
What is the difference between Poka-Yoke control Poka-Yoke and warning?
The Poka-Yoke control unit physically stops the machine or blocks the workpiece’s progress until the anomaly is corrected; the warning Poka-Yoke unit instead signals the deviation via acoustic or visual alarms (Andon), requiring the operator’s intervention.
How is Poka-Yoke the Jidoka principle connected?
It Poka-Yoke is the practical tool with which Jidoka (self-organization) is realized: it gives machines and workstations the ability to automatically distinguish a normal condition from an abnormal one, building quality directly into the process.
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