Poka-yoke can be implemented at any step of a manufacturing process where something can go wrong or an error can be made. For example, a fixture that holds pieces for processing might be modified to only allow pieces to be held in the correct orientation, or a digital counter might track the number of spot welds on each piece to ensure that the worker executes the correct number of welds.
Three types of poka-yoke for detecting and preventing errors in a mass production system
- The contact method identifies product defects by testing the product’s shape, size, color, or other physical attributes.
- The fixed-value (or constant number) method alerts the operator if a certain number of movements are not made.
- The motion-step (or sequence) method determines whether the prescribed steps of the process have been followed.
Three-step analysis of the risks to be managed
- Identification of the need
- Identification of possible mistakes
- Management of mistakes before satisfying the need