Overall Equipment Efficiency OEE

Definition of OEE

The Overall equipment efficiency OEE is a Key Performance Indicator or KPI use to evaluate how effectively a manufacturing process is utilized. Basically, the OEE is a ratio which compares the Actual production with the theoretical maximum production capacity.

Calculation of OEE

It’s a combination of 3 main ratios:

Availability, Performance and Quality for a given period of time (day, week, month…)

OEE = Availability ratio x Performance ratio x Quality ratio

Availability ratio of OEE

• Availability ratio = Actual production time / Theoretical production time
  
  

- Actual production time (hours) = Theoretical production time (hours) – Downtime (hours)

- Theoretical production time (hours) = Number of working hours

- Downtime (hours) = Number of hours where machines are down

Performance ratio of OEE

• Performance ratio = Cycle time x Actual Production/ Actual Production time

- Cycle time (hours/item) = 1 / Maximum production capacity (items/hour)

- Actual Production = Quantity of manufactured items (including rejected products)

Quality ratio of OEE or Yield

• Quality ratio or Yield = (Actual Production - Rejected Production)/ Actual Production

- Rejected Production (items) = Quantity of manufactured items that didn’t reach quality requirements

• Try our free online Overall Equipment Efficiency OEE calculation tool