An Andon system makes abnormalities visible and creates a disciplined response path. It is most effective when signaling, response, containment, problem solving, and leadership behavior are all designed together.
Definition
An Andon system is a visual or audible signaling method used to alert a team that an abnormal condition needs attention. It may appear as a light, sound, board, cord, button, screen, message, or digital alert. In Lean systems, Andon is closely connected to Jidoka, or building quality into the process by detecting abnormalities and responding before defects continue downstream.
The purpose is not only to signal trouble. A good Andon system defines what counts as abnormal, who responds, how quickly they respond, what containment is required, when the process stops, and how the issue is learned from afterward. It turns problems into visible events that can be addressed at the source.
History
Andon is associated with the Toyota Production System and visual workplace control. The word originally referred to a Japanese lamp or signal. In manufacturing, the concept evolved into a practical mechanism for operators to call for help, signal abnormalities, and prevent defects from continuing through the process.
As Lean spread, Andon moved beyond assembly lines. Today it can be used in healthcare, service operations, logistics, software support, laboratories, call centers, and office processes. The physical signal may change, but the management principle stays the same: make abnormal conditions visible and respond with urgency, respect, and problem-solving discipline.
When to Use
Use an Andon system when abnormalities need immediate attention and the team benefits from a clear escalation path. Good triggers include quality defects, missing materials, equipment faults, safety concerns, tooling problems, unclear work instructions, blocked flow, customer-impacting service failures, and process conditions that could create rework or delay.
Andon is most valuable where people are expected to stop, call, and wait for support rather than hide problems or work around them. It is less useful if the organization punishes signal use, has no response capacity, or treats every alert as noise. Before implementing Andon, leaders must decide which problems deserve a signal and how support will be provided.
Step-by-Step
- Define abnormal conditions. Specify the defects, delays, shortages, safety concerns, equipment states, or process gaps that require an Andon signal.
- Design the signal method. Choose a visual, audible, physical, or digital signal that is clear, fast, and visible to the people who must respond.
- Define response roles. Identify the first responder, backup responder, escalation owner, and decision authority for stopping or restarting the process.
- Set response expectations. Define target response time, containment actions, communication steps, and restart criteria.
- Train users and leaders. Teach operators when to signal, how to signal, what to expect after signaling, and why raising problems is part of good work.
- Pilot and tune the system. Start in a focused area, track signal frequency, response time, root causes, false signals, and unresolved issues.
- Link to problem solving. Use repeated Andon signals to drive root cause analysis, standard work updates, poka-yoke, maintenance improvements, or material system fixes.
- Sustain through daily management. Review Andon performance during tier meetings, leader standard work, and continuous improvement routines.
Examples
- Assembly line quality issue: An operator detects a missing component and pulls an Andon cord. A team leader responds, contains the unit, checks recent units, and escalates repeated misses to material presentation and standard work review.
- Equipment fault: A machining cell uses stack lights to show normal running, waiting for material, tool change, quality hold, or maintenance needed. The color states help support teams respond to the right issue quickly.
- Healthcare process: A clinic uses a digital Andon board to signal rooms waiting for lab results, provider review, or discharge documents. The board makes delays visible before patients experience long waits.
- Service operations: A customer support team flags cases that exceed response-time thresholds. The signal triggers supervisor review and helps identify recurring knowledge-base gaps.
- Warehouse flow: Pickers use a button to signal missing inventory or location errors. Repeated signals are reviewed to improve inventory accuracy and slotting discipline.
Common Pitfalls
- No response discipline. If signals do not receive timely support, people stop using the system or work around problems.
- Punishing the signal. Andon must make problems safe to expose. Blaming the person who signals destroys the system.
- Too many vague alerts. If everything is an Andon, the system becomes noise. Define abnormal conditions clearly.
- No containment logic. The team must know whether to stop the process, hold product, call maintenance, add inspection, or continue under controlled conditions.
- Tracking counts without solving causes. Andon frequency is useful only if repeated signals lead to improvement.
- Technology before management behavior. Screens, lights, and buttons cannot compensate for poor response routines or weak leadership follow-through.