Definition OEE definition - Overall Equipment Effectiveness - Definition of A (Availability)


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I am going to post a side question here.
We are working with defining the OEE. A discussion that we hasent solved is the definition of the factor A (Availability).
We have a total time of 24 hours which is our theoretical production time, we have a planned preventive maintenance time for 3 hours and of course we have our unplanned stop time.
Depending on how we choose to define A we can get two factor A numbers
87.5% or 100% (if you calculate the unplanned stoptime to zero).
We are also going to implement SMED, and the first focus would be to look at the 3 hours of planned preventive maintenance.


Fully vaccinated are you?
My understanding is it would be 87.5% because the equipment is technically not available for production during preventive / predictive maintenance.

Below are the basics - I'll let the folks who use this a lot discuss your specific question of the definition of the A (Availability) factor.

OEE means overall equipment effectiveness. It is a method to find out overall effectiveness of equipment. It is obtained by multiplication of three ratios.

1. Availability ratio - Time for which equipment was available for operation divided by total calender period for which OEE is being calculated.
2. Quality Ratio - Quantity of "A" grade/Prime grade material produced divided by total production (Off grade+Prime grade)
3.Performance Ratio - Rate of production divided by Capacity of machine to produced.

Normaly OEE is presented in terms of percentage.

OEE definition - Overall Equipment Effectiveness - Definition of A (Availability)

Elsmar Cove Wiki: Overall Equipment Effectiveness


Hi DavidB,

In order to achieve a calculation according definition of OEE you should define A as:

A = ((Calendar Time - (shutdown losses + major stoppages)) / Calendar Time) x 100%

shutdown losses - planned maintenance loss + shutdown maintenance loss
major stoppages - equipment failure loss+ processo failures loss

Rob Nix

Availability, as part of the OEE calculation, has to be determined and defined in advance by the group concerned with the outcome. Different organizations are concerned with different stats.

The SAE R&M Guidelines identifies several different types of "avaliability": 1) achieved, 2) intrinsic, 3) operational, and 4) overall equipment...

Before becoming too dogmatic about what the "A" stands for, we must get the concerned parties together and agree on what is expected.



See the attachment. I should have some more in my archieve, I will look for, and post it.
I like page no. 9, where results from 2 shifts are compared. As always, it is true, that you have to know, what is behind the numbers, for a good interpretation. In my interpretation, the key elements, is planned versus unplanned, and target versus results.


  • OEE_guide_Vorne.pdf
    1.5 MB · Views: 774


Re: Oee

A discussion was had at work the other day debating the application of scheduled lunches and its impact to the OEE target. Historically our organization has taken a "hit" for counting a scheduled lunch as available time even though no technicians were available to run the equipment. My contention is that it is scheduled downtime, or scheduled to be non-productive and we should adjust our targets accordingly. On the flip side there are some occasions where we staff the line through the scheduled lunch. On those days our OEE is slightly inflated due to our use of available manpower.

How should we measure ourselves?
Thank you for any help.


Involved In Discussions
Hi David,

A - Should be

A = Operating Time/ Planned production time

Planned production time = Shift length- breaks
Operating time= Planned production time - downtime

Normally getteing 85% OEE is considered as world class, my current company OEE is between the range of 72 ~80 % . It also depends on how every company interprets the result.

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