VSM Studio
VSM guide / Lean tools / OEE calculator
OEE calculator
Overall Equipment Effectiveness in one screen. Enter planned time, stops, ideal cycle time and part counts: see OEE, the three factors and exactly where the time goes. Free, no sign-up.
How OEE is calculated
Availability
Run time ÷ planned production time. Run time is planned time minus stops: breakdowns, setups and adjustments, material shortages.
Performance
(Ideal cycle time × total parts) ÷ run time. It catches small stops and slow running that never show up as downtime.
Quality
Good parts ÷ total parts. Scrap and rework count as losses, even when the part is fixed later.
OEE
Availability × Performance × Quality. 85% is considered world class; most plants start between 40% and 60%.
From OEE to TPM
OEE tells you how much capacity is hiding in the machine and which of the six big losses is biggest. Total Productive Maintenance goes after them: autonomous maintenance by operators, planned maintenance, quick changeovers for setup loss, and root-cause fixes for defects. Attack the biggest bar first.
In the VSM Studio builder, open OEE on any process box: it starts from that step's uptime, cycle time and scrap, and Apply to map updates the box so the load chart, lead time and simulation reflect the real capacity.
Questions
What is a good OEE score?
World class is about 85% (90% availability, 95% performance, 99.9% quality). Most discrete manufacturers start between 40% and 60%, which means there is a lot of capacity to win back before buying equipment.
What is the difference between OEE and uptime?
Uptime only covers availability. OEE also counts running slower than the ideal rate and making defects, so it is always lower than uptime and closer to the truth about capacity.
What ideal cycle time should I use?
The fastest rate the process is designed to run a good part, from the machine spec or the best sustained rate you have seen. Not the average, or performance losses hide inside it.
Should planned maintenance count as downtime?
If it is scheduled outside planned production time, leave it out of planned time. If the machine is supposed to run and is stopped for maintenance, count it as a stop.