The OEE figure for a machine can be calculated as *Availability × Productivity × Quality × 100%*

- The
**Availability**is the total production time divided by the planned production time. - The
**Productivity**is the planned cycle time divided by the actual cycle time. - The
**Quality**is the quantity of good parts produced divided by the total quantity of parts produced this takes into account all scrapped parts).

The Actual production time is the time the machine is available to run, i.e. is not stopped for any breakdown or material or tooling issues etc.

The Planned production time is the total shift time for the machine less any planned stoppage. i.e for planned maintenance, warm up, clean down, lunch breaks etc.

The Planned cycle time is the projected time to produce one part. This normally would be the CNC machining time plus the loading and unloading time for each part.

The Actual cycle time is the time the machine was producing parts divided by the total number of parts produced (scrapped parts included).

The quantity of good parts is simply the number of parts produced that would pass inspection; this is the total number of parts produced minus the number of scrapped parts.

Each figure has to be available for each job on each machine for the OEE calculation to be carried out correctly.

The machine stoppages need to be entered into the database by the operators, normally using a bar code reader, to signal the reason each time the machine tool stops. And the planned cycle and handling times must be entered either into the CIMCO database, or into an Excel spreadsheet.