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What is the Maximum Speed of the Machine

For the performance rate, the maximum speed of the machine must be determined in order to calculate the theoretical production capacity. The value of the Theoretical output answers the question: ‘How much could the machine have produced THEORETICALLY during its Running time’.

Definition of ‘Theoretical output’

The maximum speed of the machine can be seen from two angles. The first is the Name Plate Capacity or NPC. The second is the Standard (here further referred to as Theoretical Speed). Both are used in calculating the Performance rate. Below both types of speed are described.

Two types of maximum speed

The maximum speed of the machine can be seen from two angles. The first is the Name Plate Capacity or NPC. The second is the Standard (here further referred to as Theoretical Speed). Both are used in calculating the Performance rate. Below both types of speed are described.

Name Plate Capacity

The maximum speed of the machine can be seen from two angles. The first is the Name Plate Capacity or NPC. The second is the Standard (here further referred to as Theoretical Speed). Both are used in calculating the Performance rate. Below both types of speed are described.

Product specific speed

On most machines several different products are produced and these products are made at different speeds and under different conditions.

There are two major explanations to the difference in production speed:

  1. Some products are ‘harder’ to produce than others. The difference in speed is actually an indicator of the fact that we do not always control the process for each product. In terms of OEE, the maximum speeds for all these products should be set the same, namely the highest speed! After all, we want to reach our goal of eliminating the losses caused by ‘difficult products’, and, therefore, we must make them manifest!
  2. There are physical reasons that determine the difference. The fact is that, under the same circumstances, it takes longer to bring 1 liter of liquid to a certain temperature than 0.5 liter. In such a situation, a product of 0.5 liter could be produced twice as fast as another product of 1 liter.

The Standard (= Theoretical Speed)

In situations as described under point 2, the performance rate is not measured with the NPC but with the maximum speed of that product on the machine.

The maximum speed that is specific for a particular product-machine combination is called the Standard.

A certain machine might have a different maximum speed for each product and thus have more than one Standard, whereas there is only ONE NPC.

One product, produced on several machines, might have a different standard on each machine, depending on the design of the machine. The actual output can NEVER be higher than the theoretical speed!

Plan Speed

More than once we notice resistance against using the real maximum speed of the equipment to calculate OEE.

It is stated this would not be realistic since others calculate or plan with more realistic speed settings.

Since OEE Coach wants to visualize ALL losses on the equipment, using the speed that is actually planned with, would hide the difference between what could be done theoretically.

This is why OEE Coach also allows to define the speed where planners hope for.

This value can be used to show the team whether they are ‘on target’ or above or below. Plan-speed can also be different for each product on a specific machine.

Set Speed

Usually the operator will explain why he cannot run the machine at what is considered to be the maximum speed for a specific product. He will set the speed at such a value where he is experiencing as little problems as possible, in other words: he searches the speed where the process is most in control.

The set speed can be different from product to product and even from run to run, depending on many parameters, like the used raw materials, the temperature or humidity etc. When the set-speed gauge of the machine works correctly, there can be no more actual output as the machine is set to produce.

Reduced Speed

The difference between the theoretical maximum speed of the equipment and the speed the equipment is set to run to (‘Set Speed’), is called Reduced Speed. Reduced-speed therefore is caused by deliberately setting the equipment to run at a lower speed.

Minor Stops

The difference between the speed the machine is set to run at (‘Set Speed’) and what actually was brought out, is called ‘Minor Stops’.

Any speed fluctuations and short interrupts causing to reduce the output are caught here. Usually these stops are smaller than 1 minute. They are not actually being registered but calculate by comparing the expected output at the set speed with the actual output. As with reduced speed, minor stops lower the performance rate.

Short Stops

Where MINOR stops are calculated, thus not actually detected, the SHORT stops are really identified as such, however they are too small to be individually assigned a reason-code.

Short stops lower the availability and are all grouped together in the container ‘Short Stops’

Since it all just a matter of definition, the user can define how long a stops should take in order to place it in which category:

  • Smaller than 1 minute usually go into minor stops. (Performance loss)
  • Between 1 and 5 minutes go into Short Stops. (Availability Loss)
  • Larger than 5 minutes are identified with reason. (Availability Loss)

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