Production and OEE
What is Andon?
An andon is a visual signal that shows machine or line status and calls for help when there is a problem: stack lights, cords, boards and digital andon alerts.
Quick answer
An andon is a visual and audible signal that shows the status of a machine or line and calls for help the moment something goes wrong. It can be a stack light, a pull cord, a push button or a digital board. The idea is to surface problems immediately so they are fixed at the source.
Updated 30 October 2026. Written by the Ajinkya Technologies engineering team, reviewed by Amey Kadle.
Andon explained
Andon comes from the Toyota Production System, where any operator can stop the line or call a team leader when they see a problem. It supports jidoka, the principle of building quality in by stopping to fix abnormalities rather than passing them on.
The classic hardware is the stack light on a machine: green for running, amber for a warning or waiting, red for stopped. Pull cords and buttons let operators raise calls for maintenance, quality or material. Andon boards above a line show which station needs help, and the response team walks to it.
Digital andon connects those signals to software. A stop on a machine raises a call automatically, the right team gets a message on a phone or a smartwatch, response and repair times are recorded, and the event lands in the downtime and OEE records with its reason. The cultural part matters as much as the technology: andon only works if people are thanked, not blamed, for raising it, and if someone responds quickly every time.
Key concepts
- Visual and audible status signals
- Operators can call for help or stop the line
- Supports jidoka, building quality in
- Digital andon routes calls to the right team
- Response and repair times are recorded
Questions
What do andon light colours mean?
Common conventions are green for running, amber for a warning or waiting state, and red for stopped or a fault. Plants should define and display their own standard so every line uses the same meaning.
What is digital andon?
An andon system where machine signals and operator calls go to software that notifies the right team, tracks response time and records the event against downtime and OEE.
Does andon slow production down?
Stopping to fix a problem costs minutes; passing defects or hidden faults downstream usually costs far more. The goal is fewer, shorter stops over time.
References
How we help with andon
Our MES and connected worker systems turn stack light and button signals into routed alerts, record response and repair times, and feed each event into downtime and OEE dashboards.
Interactive 3D demo with simulated data: watch OEE, counts and the plan react to a stop.
Related terms
Want this measured on your own line?
Tell us your process, machines and ERP. An engineer, not a salesperson, replies within 24 hours with what we would measure first.