Stop classes

The stop class identifies the faulty machine when there are multiple machines in the line. Every reason for a machine to stop is associated with a specific stop class.

These stop classes are available:

• Stop: The machine has stopped for a legitimate reason.
• Blocked: The material cannot pass through this machine because a subsequent machine has stopped.
• Starved: The material is not reaching the machine because the preceding machine has stopped.
• Unknown: Sometimes, when machine stops are recorded by PLCs, the reason for the stop can remain unknown. This indicates that the stop classification is also unclear. However, if the operator provides an explanation for the machine stop, both the reason and the classification become identified.

If a machine on the line stops for a valid reason, these issues can arise:

• Machines further along the production line can be starved of material, causing to stop.
• Machines that are currently processing materials can become blocked if the materials cannot move to the next stage, which can also lead to a halt in operations.

Machines that are blocked and starved propagate from the root cause machine, which is initially only the machine that is stopped. Eventually, the machines upstream and downstream become blocked and starved.

If buffers exist between machines, the line can operate longer without causing blockage or starvation of the machines. However, if the root cause machine remains blocked for an extended period, eventually all machines in the line gets affected.

If the bottleneck machine frequently becomes blocked or experiences starvation, then MES reports can help identify the underlying cause. This information can assist continuous improvement teams in conducting further investigations and making necessary improvements to the root cause machine, ultimately reducing the frequency of bottleneck interruptions.