Andon: Real-Time Visual Alerts for the Shop Floor

Andon is a lean manufacturing visual management system that signals production status and alerts teams to problems in real time. The Japanese word "andon" literally means lantern or lamp. In this manufacturing glossary entry, we explain how Andon works, provide measurable examples, and show why it matters for scheduling.

What Is Andon?

Andon is a communication tool that gives operators the power to signal when they encounter a quality defect, equipment malfunction, material shortage, or any abnormal condition. The signal can be a stack light mounted on a machine, a large overhead display board visible across the shop floor, or a digital notification in a manufacturing execution system.

The core principle behind Andon is Jidoka — the lean concept of building quality into the process by stopping to fix problems immediately rather than passing defects downstream. When an operator pulls the Andon cord or presses the Andon button, the system communicates three things:

1. Where — which workstation or machine has the problem.
2. What — the type of issue (quality, equipment, material, safety).
3. Urgency — how quickly a response is needed.

How Andon Works in Practice

A modern Andon system operates on a simple escalation model:

• Level 1 (Yellow): Operator identifies an abnormality and triggers the Andon signal. A team leader has a defined window — typically 60 to 90 seconds — to respond.
• Level 2 (Red): If the team leader cannot resolve the issue within the response window, the line stops and a supervisor is notified. The problem is now a priority.
• Level 3 (Escalation): If the issue persists beyond a second threshold — say 10 minutes — maintenance, engineering, or management are paged automatically.

Every Andon activation is logged. Over time, the data reveals patterns: which machines trigger the most alerts, which shifts have the most stoppages, and which problem types recur. This data drives targeted continuous improvement efforts.

Example with Numbers

An electronics assembly plant running two shifts tracked these results after installing an Andon system across 8 production lines:

• Average response time to problems dropped from 12 minutes to 2.5 minutes — operators no longer had to leave their station to find a supervisor.
• Defective units reaching final inspection decreased by 35% in the first quarter because problems were caught and corrected at the source.
• Unplanned downtime decreased by 20% because recurring issues were identified through Andon data and permanently fixed through root-cause analysis.
• Daily throughput increased by 8% because less time was lost to cascading defects and extended stoppages.

The Andon system did not fix problems itself — it made problems visible immediately so that people could fix them faster.

Why Andon Matters for Production Scheduling

Andon directly affects scheduling reliability:

• Faster problem resolution means fewer and shorter unplanned stoppages, reducing the gap between scheduled and actual production.
• Real-time visibility lets planners see which lines are running, which are stopped, and why — enabling faster rescheduling decisions.
• Data-driven maintenance from Andon logs helps predict equipment issues before they cause schedule-breaking breakdowns. This connects directly to TPM (Total Productive Maintenance).
• Accurate capacity assumptions improve when chronic problems are eliminated. Scheduling software like RMDB produces better results when the underlying capacity data reflects reality.

As the lean manufacturing guide explains, Andon is one of the two pillars of the Toyota Production System through its connection to Jidoka — building quality in at every step.

Related Terms

• Jidoka — The lean principle of autonomation (automation with a human touch) that Andon supports by empowering operators to stop production for quality issues.
• Visual Management — The broader system of visual tools including Andon boards, Kanban cards, and production status displays.
• Poka-Yoke — Error-proofing devices that prevent defects from occurring, complementing Andon which detects them when they do occur.

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See all lean and scheduling terms in the Manufacturing Glossary.