Lean encourages and systemizes the process of unhiding and solving problems. There are many tools like 5S, visual factory in place to make sure wastes are unhidden and bought to spotlight. Sometimes the problem itself provides the trigger to start the problem solving action. For an example, if the inventory is piling up in one place, higher inventory on the work floor itself will catch the attention and will initiate the problem solving process. But on the other hand, there can be some instances where when you find a problem, quality or process related, you have to pass a signal to the respective people. For an example, if your machine is not functioning properly, you will have to convey that message to the mechanical or technical divisions to get it sorted. This is where Andon signals come to play.
Main purpose of Andon is getting attention to the problem. Common practice is to use a light (In Red most of the cases). When there is a problem in a particular area, user will switch that light on. This will trigger the problem solving process. Sometimes, lights are combined with a sound making device (like a siren) to get the message out. These devices can be arranged in different formations like Andon boards or as work cell Andons.
Some times Andon signal can tell in particular whose attention is required, while sometimes it can just convey the message “Attention Required”. For an example when there is a problem with a machine, the person who is reporting the error will be able to direct the problem to engineering department by selecting the relevant button. But if that person is not sure of who should be informed, he might just put up a common problem indicator so that supervisor or the team leader will be able to work to solve the problem.
Andon can be built into machinery and other equipments as well. For an example, if your machine is overheated, there can be an Andon signal to indicate that to you. This can act as a problem prevention or PokaYoke as well.
Although the common practice is to use lights, there are very high end solutions like computer integrated systems. They serve the same purpose, but the observers can get information from one screen. There can be very simple solutions on the other hand. For an example hanging a red colored card can serve the same purpose. Id doesn’t matter what is the mechanism you are using, as far as you can send the message across.
Andon is a critical part of visual factory concept. Mostly used with other tools like 5S, Poka Yoke, and work cells.