We’re going to unravel the mystery of ‘Overall Equipment Effectiveness,’ or OEE for short. Imagine you have a super gadget that can do amazing things. OEE is like a report card for this gadget, telling us how well it’s performing compared to its full potential
So, how do we calculate this super-important score? OEE is a bit like a recipe with three key ingredients: Availability, Performance, and Quality. Each of these ingredients plays a crucial role in determining the effectiveness of our equipment.
OEE = Availability × Performance × Quality
First, let’s talk about ‘Availability.’ It’s like checking if your super gadget is ready for action when you need it. If your machine is supposed to run for 8 hours but only runs for 6 because it breaks down or lacks materials, its availability is reduced. We measure this by comparing the scheduled run time to the actual run time. This part of OEE helps us understand how much production time we’re losing when our machine isn’t running as planned.
Availability = Run Time / Planned Production Time
Run Time is Planned Production Time minus Stop Time, where Stop Time is defined as all time when the manufacturing process was intended to be running but was not due to Unplanned Stops for example Breakdowns or Planned Stops such as Changeovers and retooling.
Run Time = Planned Production Time − Stop Time
As per the example above:
Availability = 6 / 8 = 0.75
Next is ‘Performance.’ Think of this like checking if your super gadget is working at its fastest and most efficient speed. If it’s supposed to make 100 widgets an hour but only makes 80, it’s not performing at its best. We calculate this by comparing the machine’s actual cycle times to the ideal cycle times. This shows us how much production we’re losing because our machine isn’t running as fast as it could.
Performance= Actually Produced Parts/ Maximum Possible Parts Prodcution
As per the example above:
Performance= 80/ 100 = 0.8
Performance can also be calculated as the ratio of Net Run Time to Run Time.
Performance = (Ideal Cycle Time × Total Count) / Run Time
Ideal Cycle Time is the fastest cycle time that your process can achieve by the machine. So, when it is multiplied by Total Count the result is Net Run Time, or the fastest possible time to manufacture the parts.
Because the rate is the reciprocal of time, Performance can also be calculated as:
Performance = (Total Count / Run Time) / Ideal Run Rate
Performance should never be greater than 100%. The maximum performance is the maximum possible speed of the equipment.
Finally, we have ‘Quality.’ This is all about ensuring that the super gadget makes products that are up to the mark. If it makes 100 widgets, but 10 are defective, then it’s not producing quality work. We measure this by comparing the number of good products to the total produced. This tells us how much time and resources are wasted on making products that don’t meet our quality standards.
Quality = Good Count / Total Count
As per the example above:
Good parts 100-10=90
Quality = 90/100 = 0.9
To get our OEE score, we multiply the Availability, Performance, and Quality scores together. This gives us a powerful number that shows how effectively we’re using our equipment. It’s like having a health check-up for our machines, making sure they’re in top shape and giving us the best value for our investment.
Putting it all together
OEE = 0.75*0.8*0.9=0.54
How do you know if your calculated OEE is good? Well, any OEE score greater than 85% is considered world-class. Most manufacturing operations have an OEE score between 65% and 85%. It’s safe to assume that the processes of any plant with an OEE score of less than 65% suffer from considerable deficits.
Remember, a high OEE score means our machines are available when we need them, running at their best speed, and producing top-quality products. So, let’s aim high and keep our equipment effectiveness in top gear!
