Stop classes
Every machine stop reason also has a stop class associated with it.
The stop class is used to identify the root cause machine when there are multiple machines in the line.
These are the available stop classes in Infor MES:
- Stop: The machine is stopped for a genuine reason.
- Blocked: The material cannot pass through this Machine, because a later Machine is stopped.
- Starved: There is no material reaching this machine because an earlier machine is stopped.
- Unknown: Sometimes, when machine stops are recorded by PLCs, the stop reason is unknown. This means the stop class is also unknown. If the operator explains the machine stop, then the reason and the stop class become known.
If a machine in the line stops for a genuine reason, then these issues can occur:
- Machines further down the process will be starved of material, and will therefore stop as a result
- Machines earlier in the process will be blocked from creating new material because the material cannot progress down the line, and will therefore stop as a result
Blocked and starved will propagate out from the root cause machine, so it might initially be just the root cause machine which is stopped. Eventually, the machines up and down stream become blocked and starved.
If there are buffers between machines, then the line can cope for longer without machines becoming blocked or starved. However, if the root cause machine stays blocked for long enough, eventually all machines in the line are affected.
If the bottleneck machine is regularly blocked or starved, then MES reports can help detect the root cause machine. This can aid the continuous improvement teams to do further investigation and improve the root cause machine to reduce bottleneck stops.