Mean time between failures or MTBF is a KPI commonly used to describe the reliability of an manufacturing line. A failure is an unplanned downtime event (red stops). MTBF can be seen on the Live page KPI section.
In Factbird we calculate this KPI over a given time period e.g. 8 hours. Within this time window we calculate the time from the last event of unplanned downtime to the next unplanned downtime event.
If there are any planned downtime in between that time is subtracted from the time between failure. At last we calculate the median value of the time between failures.
We do not take into account changeovers, planned downtime and unmanned time because all of these are related to availability and not reliability of the line.
If you want to look at MTBF for individual stops we recommend looking at the scatter plot instead. Looking at the scatter plot for one or more stops allows us to get more nuances on frequency and duration of stops. The scatter plot is found on the Analytics page.