Overall Equipment Effectiveness is a measure of how well assets in a production/manufacturing process are utilised. It's expressed as a percentage of the plant's full or theoretical maximum capacity and is calculated as follows:

OEE = Availability x Performance x Quality

Where:
Availability = Operating Time / Scheduled Time
Performance = (Parts Produced x Ideal Cycle Time) / Operating Time
Quality = (Units Produced - Defective Units) / Units Produced


An indicator of productivity, OEE is seen as a key metric by manufacturers looking to understand the causes of inefficiency within their operations. Because it can be universally applied, OEE is also used to benchmark improvements and draw comparisons between processes, sites or companies.

The 'OEE Estimator' below can be used to gain familiarity with this metric. Enter information related to your business, or play around to get a feel for the impact different inputs have on the final result.


OEE Estimator

Availability

How many hours per week is production scheduled?
Include for scheduled maintenance and rota'd breaks, but not breakdowns or unplanned events


In a typical week, for how long is production stopped during the scheduled running time?
Include for breakdowns, resolving quality issues and other unplanned events


Performance

What's maximum throughput, under ideal circumstances?
Likely never achieved


What production rate is typically achieved?
Regardless of quality


Quality

How many defects are produced when operating at the rate above?
Units which don't meet quality criteria, so need to be scrapped or reworked


NOTE: Data entered below isn't stored, so if you want to record your results you need to screenshot or print this page.


OEE

0%

Availability

0%

Performance

0%

Quality

0%


What does good look like?

Due to the nauture of the calculation, achieving a high OEE is challenging. Scores of 95% in each of the 3 areas only gives an OEE of just under 85.7%. World-class is considered between 75% - 90% depending on product complexity and variety, and 60% manufacturers .

As such, lower scores are common. If you entered data for your process above and got a lower result than you were expecting, know that many companies start out with scores < 40%.

Depending on your product and process the different components can be easier or harder to improve. It's rare for a company to get similar scores in each area - particularly those just starting out - and it's not likely to be helpful to aim for this.

Like any KPI, pursuing improvements in OEE without regard for the characteristics of your specific product, market and processes is unlikely to bring about sustainable improvement. Using the measurement effectively involves looking at performance in detail. To do this users of OEE consider "Six Big Losses", common causes for inefficiency.


Six Big Losses

Each OEE component has 2 main types of loss:

Availability

Equipment failure - e.g. breakages, emergency shutdowns, faults
Planned stops - e.g. cleaning, retooling, starting up/shutting down

Performance

Speed loss - e.g. inconsistent inputs, lack of maintenance, machine age/condition
Minor stops - e.g. jams, clearing obstructions, adjusting settings

Quality

Start up defects - e.g. incorrect settings, equipment warming up/cooling down, incompatibility
Production defects - e.g. incorrect settings, operator error, starting up/shutting down