Downtime
The time during which an asset or production line is not available for use.
How it works
Downtime is split into two kinds:
- Planned downtime: scheduled stops for maintenance, changeovers, cleaning, or shutdowns. You know it is coming and can prepare.
- Unplanned downtime: stops caused by failures, missing material, or other surprises.
Downtime is usually measured in minutes or hours per asset or per line, and often tagged with a reason code so that causes can be compared.
Why it matters
Unplanned downtime is where maintenance costs show up on the production side. A stopped line loses output, may scrap work in progress, and can delay customer orders. That is why many maintenance strategies aim to turn unplanned stops into shorter planned ones.
Downtime is also the input for availability, one of the three factors in OEE.
In practice
Teams record when a stop started, when it ended, and why. The reason matters more than the minutes. "Breakdown" as a reason tells you little; "conveyor drive tripped on overload" tells you where to look.
Be clear about where the clock starts and stops. Does downtime include waiting for a technician, waiting for parts, and the restart and first good part? Different answers give very different numbers, so pick one definition and keep it.