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Manufacturing & Maintenance 7 min read Published 24 August 2026

Andon systems: the lean tool everyone installs and most plants stop believing

By Frank Guo · Technology & Product Leadership, addanode

TL;DR — An andon system makes production problems visible the moment they happen: a light, a board, an alert that says "this station needs help now". The hardware ladder runs from stack lights (hundreds of rand, manual) through wireless call buttons to digital andon boards fed by real machine data. Most andon installations decay the same way: lights that stay red with no response, boards fed by manual entry nobody trusts, escalation that exists on a poster but not in practice. The fix is architectural, not motivational — trigger from machine signals where possible, escalate automatically to phones (not just the ceiling), and log every event with a response time. Done that way, andon becomes the front end of your downtime data instead of decoration above it.

What andon is — and the ladder of ways to build it

Andon (行灯 — the lantern) is the lean principle that problems must announce themselves immediately and visibly, so help arrives while the problem is small. In hardware terms, South African plants meet it at four rungs:

RungWhat it isHonest assessment
Stack lightsRed/amber/green towers per machine, wired to machine state or a switchCheap and instantly understood — but only as good as the line of sight and the response culture
Wireless andon / call buttonsOperators press for maintenance, materials, quality; receivers buzz or displayGood for help-calls people must initiate; adds radio reach; still manual, still unlogged in basic kits
Digital andon boardsScreens showing line status, calls and counts, fed manually or from machinesPowerful when machine-fed; when manually fed, they inherit every problem of manual dashboards — and die the same death
Data-driven andonMachine signals trigger status automatically; escalation goes to phones with timers; every event loggedThe version that survives — because the light, the alert and the downtime record are the same event

Why andon projects decay — three predictable failures

  • The unanswered light. A red lamp with no escalation path is a decoration. Within weeks the floor learns that red doesn't summon anyone, and the system is dead — still lit, but dead. Working andon has timers: unacknowledged calls escalate — station → supervisor's phone → maintenance manager — automatically.
  • Manual triggering under pressure. When operators must stop to press the button, the busiest (worst) moments go unrecorded — precisely the moments andon exists for. Machine-triggered status (from counters, current, run signals — the same retrofit sensing that feeds OEE) fires whether or not anyone has a free hand. Buttons stay for what machines can't know: materials, quality, "come look at this".
  • No memory. A light that turns green leaves no record — so andon events never become Pareto charts, and the same station calls for help every Tuesday forever. Logged events with response times turn the andon system into the front end of downtime analysis: the call is the reason code.
Three predictable ways andon dies Andon decays in the same three ways: a light nobody is obliged to answer, a button that cannot be pressed when things are worst, and a system with no memory of what it signalled. Each has a mechanical answer — an escalation timer, machine-triggered status, and a logged event with a response time — and none of them is about the colour of the lamp. The failure, and its answer What actually happens The unanswered light A red lamp with no escalation path is a decoration. Within weeks the floor learns that red summons nobody — still lit, and dead. Working andon has timers: station, then supervisor's phone, then maintenance manager. Manual triggering under pressure If an operator has to stop and press a button, the busiest moments go unrecorded — which are precisely the moments andon exists for. Machine-triggered status instead Counters, current and run signals fire whether or not anybody has a free hand. Buttons stay for what a machine cannot know: materials, quality, come and look at this. No memory A light that turns green leaves no record, so andon events never become a ranked list and the same station calls for help every Tuesday forever. Logged events with response times Turn the andon system into the front end of downtime analysis, because the call is the reason code.
Three predictable ways andon dies An unanswered light, a button nobody can reach, and a system with no memory. Failure and answer → What happens The unanswered light A red lamp with no escalation path is a decoration. Within weeks the floor learns that red summons nobody — still lit, and dead. Working andon has timers: station, then supervisor's phone, then maintenance manager. Manual triggering under pressure If an operator has to stop and press a button, the busiest moments go unrecorded — which are precisely the moments andon exists for. Machine-triggered status instead Counters, current and run signals fire whether or not anybody has a free hand. Buttons stay for what a machine cannot know: materials, quality, come and look at this. No memory A light that turns green leaves no record, so andon events never become a ranked list and the same station calls for help every Tuesday forever. Logged events with response times Turn the andon system into the front end of downtime analysis, because the call is the reason code.
The three decays above, each with the mechanism that prevents it. None of them is about the lamp — an escalation timer, a machine-triggered status and a logged response time are what separate a working andon from a lit one.

Andon in the South African context

Two local specifics change the design. Load shedding: an andon system that dies with the power tells you nothing during exactly the chaos of restart — edge-buffered, UPS-backed andon (like any monitoring surviving load shedding) keeps the record through the event. Distributed supervision: with lean staffing across big floors, ceiling lights alone assume someone is looking; escalation to WhatsApp/SMS reaches the supervisor wherever they are — which in practice is what converts response times from "when noticed" to minutes.

A sensible buying path

  • Have nothing? Stack lights on the bottleneck line plus a written response rule. Cheapest possible start; teaches the culture.
  • Lights ignored? Don't buy more lights — add escalation and logging. That's a monitoring-layer problem, not a lamp problem.
  • Scaling up? Machine-triggered status with operator reason-tagging, digital boards fed from the same data, phones in the escalation chain. At this rung andon, downtime tracking and OEE are one system with three faces — which is exactly how we build it on addaNet.

Frequently asked questions

What is an andon system in manufacturing?

A visual (and increasingly digital) alerting system that signals production problems the moment they occur — via lights, boards or phone alerts — so help arrives while the problem is small. It's a core lean manufacturing tool originating from the Toyota Production System's principle that abnormalities must be visible immediately.

What's the difference between andon lights and a digital andon system?

Lights show current status to whoever happens to look; a digital system adds automatic triggering from machine signals, escalation with timers to phones, and a logged history of every event and response time. The lights are the display; the digital layer is what makes the display answered — and analysable afterwards.

How much does an andon system cost?

Stack lights run a few hundred rand per tower; wireless call-button kits from a few thousand; data-driven andon rides on production monitoring infrastructure (indicatively R40,000–R120,000 per line, covering OEE and downtime tracking too — see our price guide). If you're instrumenting for OEE anyway, andon is nearly free on top.

Why do operators stop using andon systems?

Because pressing the button stopped producing help. Every unanswered call trains the floor that the system is theatre; three weeks of that and usage collapses. Escalation timers that guarantee a response — and visible response-time stats — are what keep an andon system believed. Culture follows architecture.

Can andon work on old machines without PLCs?

Yes — the same non-invasive sensing that retrofits OEE (counters, current clamps, run-state detection) triggers andon status automatically on machines that predate digital anything. Operator buttons then cover the human-judgment calls. No PLC required, no control changes made.

Related reading

Guide

Why production dashboards fail

The trust problem andon inherits.
Guide

Shop floor data collection

The signals that drive automatic andon.
Solution

OEE management

Andon, downtime and OEE as one system.

Primary sources

Make red mean "help is coming" again.

Tell us how your floor calls for help today. We'll propose andon that triggers itself, escalates to phones, and leaves the record your CI programme needs.

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