It is very difficult to manage the timing of an assembly line without a conveyor: all stations must have completed their tasks at the same time to be able to move forward. Line yields without conveyor are 80%, compared to 90 to 100% for lines equipped with conveyor. Without a digital system, these yields are impossible on assembly lines without conveyors. This is why it seems necessary to set up a Yo-i-Don system to pace production at the rate of takt time and thus claim the same performance as lines with conveyor.
Andon used to raise alerts
Implementing an Andon system (Yo-IDon) on assembly lines allows operators to raise incident alerts. The various alerts allow actions to be prioritised and thus prioritise interventions. Les Chantiers de l’Atlantique (shipyard) categorised their levels of priority with colours:
- Green: the task is complete,
- Flashing yellow: a call has been triggered,
- Constant yellow: the request has been acknowledged,
- Red: the problem is ‘fatal’: stop the production line.
It makes operators responsible for their work area and allows them to be selfmanaging: Initially there are many support requests, but as operators come to trust the system, alerts become less frequent.
This allows managers to intervene rapidly; productivity is therefore improved. Stress is also reduced in team leader activity as they have a better overview of the production line. At Chantiers de l’Atlantique (shipyard) the system ensures that all operators have the same level of production-line information in real time.
Displays to monitor activity
Andon alone coupled to the visual management system provides transparent information on activity to all involved. Everyone knows what their priorities are and the progress of other areas. Takt time is displayed on screens in the workshop, restarts are accompanied by an audible signal and incidents are categorised and logged. With a better understanding of the overall situation, operators and team members are reassured because delays are ‘justified’ when requesting managers to assist. The production rate is more fluid, thanks to this transparent communication. For Chantiers de l’Atlantique (shipyard) the rate of advance on the line was quartered and productivity increased by 10%.
And everyone has the same working and resting times which improves morale. The manager fulfils more of a team support role than one of watching over team members. The Andon system displays alerts on screens but also via SMS and emails allowing the relevant people to be notified as soon as possible.
And the interface can be configured to display the required data (working time, user profiles …) and (the number of) incidents as a graph. Data communicated by Andon is precious and when analysed, allows managers to anticipate activity and improve overall company productivity.