Availability measures one thing: the share of the time the line was supposed to be producing during which it was actually producing. The denominator is planned production time, which is the shift length minus any time you deliberately chose not to run, such as scheduled breaks, planned meetings or a shift with no orders. The numerator is run time, which is planned production time minus all unplanned and planned-but-productive-loss stops.
The judgement call is what counts as a stop. On most bottling lines a changeover between bottle sizes or flavours counts as downtime because the line was scheduled to produce and did not. Breakdowns, waiting for material, waiting for a quality release and cleaning after a spill all count. A rule many plants use is that any stop long enough to be written on the log sheet (often 2 to 5 minutes or more) is downtime; shorter interruptions are handled under Performance.
Availability = Run Time ÷ Planned Production Time. Keep the two numbers in the same unit, usually minutes, and never let planned production time include breaks you intentionally scheduled.
Standard Procedure
- 1Start with the shift length in minutes.
- 2Subtract scheduled non-production time (breaks, planned meetings, no-order periods) to get planned production time.
- 3Add up every logged stop, including changeovers and breakdowns, to get downtime.
- 4Subtract downtime from planned production time to get run time.
- 5Divide run time by planned production time.
Lesson Summary
- ✓Planned production time excludes deliberate non-run periods; downtime includes changeovers and breakdowns.
- ✓Set a clear threshold for what gets logged as a stop so every shift calculates Availability the same way.