I have setup an analysis that should cause a "bottle neck" and it seems to be the case that the machine causing the "bottle neck" does indeed show red and in severe cases has a usage of over 100%
Carl van Rooyen
I already tried an example depends on : Load/Upload Time ,Setup/Processing Time & Time between stations based on the speed of transportation means.
It doesn't find the Bottle Neck between stations.
I have noticed with the calculation for machine utilization, that there seems to be no allowance for batch size. This may affect your results. This is what I have come up with.
As it stands this is the calculation
Machine Utilization for a station = ((setup time + processing time) *daily desired production rate for all jobs at the station / (N of shifts * shift hours * percent uptime)) *100%
From a document posted on this thread http://forums.autodesk.com/t5/Autodesk-Factory-Des
There is no batch size worked into the production rate. I believe that the Production Rate should be divided by the Batch Size to obtain the correct Machine Utilization. I have run some tests by setting daily production rate and batch size, then looked at machine utilization (+- 3700%). I then divided Production Rate by Batch size and reduced batch size to 1 and got a Machine utilization of +- 30% (More realistic according to data gathered).
The equations I used to calculate by hand are as follows
Machine Utilization=(Time Used / Time Available) * 100%
=(((Setup time + Processing Time) * (daily desired production rate for all jobs at the station /Batch Size)) / (N of shifts * shift hours * percent uptime)) * 100%
I believe this may need to be looked at by Autodesk.
Forgot to mention in my previous post that in the case that I used for my calculations, the operations performed per machine, operates on the entire batch at once.
Maybe there should be an option under the machine properties to set how many of the product pass through the machine per operation.
An example would be a machine that fills 5 bottles per operation, but the batch size is say 60. Therefore the machine would perform 60 / 5 operations. This would be worked into the Machine utilization calc.
It's so simple.
The Utilizations means :the ratio between the desired production rate & the actual production rate.
It depends upon time, Machines used for every stations.
You can find it as follows:
1- calculate the Machined time for one Part= Processing tme + Setting up Time
2-Total Parts Machined in one Shift= Machined time for one part/ No. Of Hours per Shift
3-Actual Production Rate per day = Total Parts Machined in one Shift x No. Of Shifts per day.
4-UTILIZATION = Desired Production Rate(/workday)/ Actual Production Rate per day / uptime %age x 100.
for reasonable results it shall not exceed 100%.
uptime %age may depends on the state of Physical Machines in the stations.
But Again No any indicator for a bottle Neck
In Factory design suites, it is using the following fomulars for the machine utilization:
Machine Utilization for a station=Standdard time(actual production needed time)/Takt Time(actual working time)*100%
Then Machine Utilization=(Setup time+Processing time)*Daily desired production rate/(No. of shifts *shaift hours*precent uptime*60)*100%
I understand how the equations work. My questions is.
Does the calculation take into account the batch size?
An example of my problem is as follows.
One mixing operation produces 60kg of compound
Takes 30s to setup and 3min to process
We are required to produce 10 000kg per day
A work day is 2 8 hour shifts.
Uptime of the machine is 96%
I get a machine Utilization of about 3776% (unrealistic since the information is what is currently being used)
If I divide the required production rate by the batch size then machine utilization is about 63% (more realistic)
Inputting this information into the equations the batch size is ignorred and only the required daily production is used. Should the daily production not be divided by the batch size to obtain the amount of opperations (Running time) of the machine?
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