When something goes wrong on a production line — a machine stops, a part fails inspection, material runs out — the most expensive thing is the time it takes for the right person to find out. In many factories, operators walk off to find a supervisor, phone the maintenance office or simply wait. An andon system fixes this by giving every operator a fast, visible way to call for help, and by making sure someone responds.
Where andon comes from
Andon originated in the Toyota Production System, where operators could pull a cord to stop the line when they found a problem. The idea is respect for the operator's judgement and a culture where problems are surfaced immediately rather than hidden. Modern andon systems keep the principle and add digital tools: tablet buttons, mobile alerts, escalation rules and data.
How a digital andon works
- Operator raises a call: on a tablet or button at the machine, choosing the call type — maintenance, quality, material, supervisor, safety.
- Responders are notified: on mobile phones, screens or stack lights, with machine, call type and time.
- Acknowledgement: a responder accepts the call, so others know it's handled.
- Arrival and resolution: the responder records arrival, cause and action taken.
- Escalation: if a call isn't acknowledged or resolved within set times, it escalates to the next level.
- Closure: the operator confirms production has resumed.
Call types
- Maintenance: machine breakdown or malfunction.
- Quality: suspected defect, first-off approval needed, measurement doubt.
- Material: shortage, wrong material, need for replenishment.
- Tooling: tool change or tool damage.
- Supervisor: instruction needed, staffing, schedule change.
- Safety: hazard or incident — always top priority.
Escalation rules
Escalation turns andon from a notification system into a response system. A typical rule: maintenance must acknowledge within five minutes; if not, the maintenance supervisor is notified. If the problem isn't resolved within thirty minutes, the production manager is notified. Rules vary by call type and machine criticality. The point is that no call can sit unnoticed.
Andon boards
Large screens on the shop floor show the status of each machine or line: running, stopped, open calls and elapsed time. Everyone sees problems at once, which creates urgency and helps supervisors prioritise. Boards can also show shift output against target, giving context to stops.
Learning from andon data
Every call is a data point. Over weeks, andon data shows:
- Which machines raise the most calls, and of which type.
- Average time to acknowledge and resolve by call type and shift.
- Recurring causes — the same jam, the same material shortage, the same quality doubt.
- Response bottlenecks — for example, night shift maintenance coverage.
Reviewing andon data in daily meetings turns firefighting into improvement. See tier meetings.
An example: material calls on an assembly line
An electrical equipment manufacturer introduced tablet-based andon on its assembly lines. Within the first month, material calls outnumbered all other types. The data showed most came at the start of shifts and after lunch, when line-side stock ran out because replenishment rounds were scheduled at fixed times regardless of consumption. The company changed to kanban-triggered replenishment and staged materials before shift start. Material calls fell sharply, and line output rose without any change to the assembly process itself.
Culture matters
Andon only works if operators feel safe raising calls. If calls lead to blame or are ignored, they stop. Supervisors should thank operators for raising problems, respond visibly and share what was fixed. Managers should look at call volume as information, not as a sign of poor performance.
Common mistakes
- Installing lights without defined responders or escalation rules.
- Too many call types, confusing operators.
- Not recording cause and action, so data can't be analysed.
- Treating many calls as bad, discouraging operators from raising them.
How software helps
Digital andon on tablets and phones, linked to machines, shifts and work orders, gives fast calls, reliable escalation and data for improvement. Combined with downtime tracking and OEE, it shows how quickly problems are resolved and how much capacity they cost. See shop floor management software.
Talk to us about a digital andon for your shop floor.
Measuring andon response
Three timings matter for each call: time to acknowledge, time to arrive and time to resolve. Tracking them by call type, shift and responder shows where response breaks down. Long acknowledgement times usually point to too few responders or poor notification; long resolution times point to skills, spares or root causes that need deeper work. Set realistic targets for each and review them weekly.
Linking andon to downtime and OEE
An andon call usually coincides with a machine stop. When the two are linked, the stop gets a reason automatically from the call type and the responder's notes, which improves downtime data without extra work for operators. Andon then becomes part of the loss picture rather than a separate system.
Getting started
Start with one line and three call types — maintenance, quality and material — with named responders and a simple escalation rule. Review the data in the daily meeting for a month, fix the most frequent causes, then expand to more lines and call types.
Frequently asked questions
What is an andon system?
A way for operators to signal problems — a stop, a quality issue, a material shortage — and get the right help quickly. It ranges from a pull-cord and light to digital calls on tablets and screens.
Do we need lights and sirens?
Not necessarily. Many factories use tablet buttons, screens and mobile notifications. Stack lights can be added where visual signals help.
Who responds to andon calls?
Defined responders for each call type — maintenance, quality, stores, supervisors — with escalation to managers if not acknowledged or resolved in time.
What data does andon produce?
Calls by type, machine, shift and reason, with time to acknowledge and time to resolve. This reveals recurring problems and response bottlenecks.
Can andon work in a job shop?
Yes. The principle — signal problems immediately and respond quickly — works in any environment.
