Eliminating error and safety is the main function of a poka yoke. However, for those who have tried to make a poka yoke, always something else seems possible that doesn’t make the poka yoke 100% perfect or mistake proof.
Basically, when no system is present to correct or detect and inform the error, the so called error is produced through the actions of an operator:
- by mistakenly altering the sequence or
- while mounting using a “wrong” direction of an object
- wrong position of a tool
- by not respecting the process parameters of a tool or machine
- pushing buttons in the one exception the programmer didn’t consider yet
- standing in the path of a moving object resulting in an incident or accident.
Hence it is possible to perform an non-compliant action resulting in a mistak
e or error.
A (technical) poka yoke is any system that results in the correction of the action while performing it OR a system that detects an error in the making and gives a sign to the person or machine performing the action. The best poka yoke doesn’t add any extra time for the process to complete but are parallel operating. We should be careful when applying the concept of poka yoke eg. sorting, filtering out bad parts doesn’t prevent bad parts so it can’t be called poka yoke. If the machine produces bad parts the device that olves it, is not a poka yoke. A human interaction is actually needed to talk about poka yoke. If a device checks the part after it has been made, I wouldn’t call this a poka yoke.
What we learn from this is that an error can only be made through human action and the right conditions. If the system isn’t used or in operation no real issue is at hand. If you can eliminate the action no error can be produced. The action requires a change of “energy”. Changing the type of energy needed to create the error sometimes helps to prevent it. In a later blog I will come back to this. So if we can’t eliminate the action, parallel checking and informing or stopping is the only alternative.
Most poka yoke’s focus on the end of operation or by checking initial conditions are met, but also the action itself can be checked, reaching closer to a 100% poka yoke.
Arkite developed a poka yoke to check the process. One of the key features is without adding extra operator handlings (confirmations) and thus time, Arkite’s product – Human Interface Mate – informs the operator in real time of any potential human process deviations. What’s new is that it can actually check if an operation is performed like stirring a spoon, making a torque action, cleaning a surface.
People matter! Don’t automate, autonomate.
In an example an operator has to drill holes but sometimes chooses one of the wrong holes. Using the Human Interface Mate the process will be navigated and when any potential deviation would occur the operator would visually be notified to prevent any possible error. Typical alternative solutions will check after the drilling but at this point you’ll have a scrap part. Arkite brings through HIM the logical poka yoke.