Until now, we have been discussing the background on thruput and what you need to know to find it. Let’s take a look at a couple real world examples:
Here is an example of how to calculate the POR or Probability of Run. If you think about the logic of the formula you will see that all you are doing is a simple percentage calculation of the amount of time the machine is running (MTBF) as a percentage of the total time (MTR+MTBF).
- Rate = 175 Products per Minute
- MTR = 3 Minutes
- MTBF = 60 Minutes
- POR = ?
POR = MTBF/(MTR+MTBF)
POR = 60/(3+60)
POR = 60/63
POR = .9523
In essence, there is no difference, except for moving the decimal place between POR, Efficiency, or Uptime %. What we are looking for is the probability, at any given time, that a machine will be up and running. In this scenario, it is 95.23% of the time.
Now that we have the Probability of Run calculated, we can now find the Net Output with another simple calculation:
- Rate = 175 Products Per Minute
- POR = .9523
- Net Output = ?
Net Output = Rate * POR
Net Output = 175 * .9523
Net Output = 166.65
If the machine runs 95.23% of the time and it runs at 175 products per minute, then the other 4.77% of the time it is not running. Therefore, over the entire time period, it produces at an average rate of 166.65 products per minute.
Next installment of our Thruput Series will be how to exactly find the constraint in your line using these equations.