Uptime, sometimes referred to as run time, is a key performance indicator (KPI) used to evaluate Lean manufacturing processes and prevent downtime. This metric takes into account all possible stoppages, both scheduled and unscheduled, for a more complete representation of the amount of time a production line is up and running. Manufacturers who keep track of uptime can identify any increase in stoppages and are more likely to spot maintenance issues or plant breakdowns early on.
Plant uptime is calculated by dividing scheduled operating time by the process’s actual operating time. In this formula, the actual operating time is the total available time to run after subtracting scheduled and unscheduled downtime. Downtime, the periods of time in which the production line is not operation and/or not available to operate, is seen as one of the biggest wastes in manufacturing. Causes of downtime include planned maintenance, employee breaks, adjustments, changeovers, etc., Excessive downtime not only wastes time and money, but it can easily lead to issues with quality and performance.
While plant uptime or production uptime are common calculations in manufacturing and industrial environments, some facilities measure downtime incurred during a shift and others will characterize each downtime “event” as being caused operationally, electrically, or mechanically. This can help to measure failures in industrial production equipment or provide more accurate data about the specific error, malfunction, outage, or cause of downtime.
The metric of uptime is very similar to the OEE factor availability and like plant uptime, takes total run time, planned stops, and unplanned stops into account; any unplanned downtime will lower the availability percentage. In order to effectively reduce downtime with the OEE formula, an accurate availability ratio is key. Furthermore, the more accurate data a manufacturer keeps, the easier it is to analyze trends, plan improvement projects, and evaluate success.
