How OEE is calculated
OEE, overall equipment effectiveness, is three percentages multiplied together:
OEE = availability × performance × quality
- Availability: run time ÷ planned production time. It’s what downtime costs you.
- Performance: what you made ÷ what you could have made at the ideal rate in the run time. It’s what running slow costs you.
- Quality: good count ÷ total count. It’s what scrap costs you.
Worked example from the template: Line 1 had 450 minutes of planned production and lost 47 minutes to a die change and a jam, so it ran for 403 minutes. Availability 89.6%.
At its ideal 600 metres an hour it could have made 4,030 m; it made 3,900 m. Performance 96.8%.
3,780 m of the 3,900 m were good. Quality 96.9%. OEE = 89.6% × 96.8% × 96.9% = 84%.
Getting honest numbers
- Planned production time is the shift minus planned stops such as breaks and planned maintenance. Everything else that stops the machine is downtime.
- Use the ideal rate, not the average. If you use the average, performance will always look fine and you’ll never see slow running.
- Keep the reasons list short. Eight to ten reasons get used properly; forty get ignored.
When the spreadsheet stops being enough
Mannin Systems does all of this as part of the day’s work: booked at the station as it happens, checked automatically, and linked to the jobs, stock and people involved. No retyping, and no Friday afternoon catching up.
