Definition
A sound-and-light signal board hung above the production line, used to flag abnormal conditions visually and audibly. Color meanings: red = needs immediate maintenance / yellow = running low on parts / green = normal / (optional) blue = changeover within 5 minutes; the precondition is to have a response plan in place before installing the light.
In detail
Andon is an audio-visual signal board suspended above the production line, used to visually and audibly indicate abnormal conditions. Color semantics are typically: red = requires immediate maintenance, yellow = parts running low, green = normal, with optional blue = changeover within 5 minutes. The prerequisite is to have a response plan before installing the lights; otherwise, unattended lights will train employees to ignore alarms. Andon is a key tool for in-process control in Excellent Daily Management (DM), complementing the visual management of 5S. It typically outputs abnormal alarm records and response time statistics to drive rapid response.
Example in practice
After installing andon on an assembly line, operators pulled the yellow light when parts were missing, and material handlers delivered within 5 minutes; they pulled the red light for equipment failures, and maintenance responded immediately. Through andon records, management found a workstation with frequent red lights, analyzed it, and optimized the equipment maintenance plan. Andon not only reduced line stoppage time but also cultivated employees' problem awareness.