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MTBF-MTTR

mtbf-mttr.png

How would you interpret this input to the MTBF-MTTR function for uptime and downtime, (time in seconds) how will it behave during the simulation, I input these data in a serial line assembly line, for each station, and most the time the stations are down, during the run time decreasing the total output.

My understanding is that the machines will run for a period of time given by the uptime distribution and then it will go down any number between 10 minutes to 180 minutes.

any help will be appreciated

FlexSim 18.1.1
mtbf mttr
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tannerp avatar image tannerp commented ·

Hi @yoni A,

For a detailed explanation of how to interpret your MTBF/MTTR input, you can refer to the User Manual section dedicated to this tool. I've uploaded this image of how to quickly access this in the software.

Hopefully this helps!

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Emily Hardy avatar image Emily Hardy ♦ tannerp commented ·

@yoni A, did this answer your question?

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yoni A avatar image yoni A tannerp commented ·

no, @Emily Hardy

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1 Answer

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tannerp answered tannerp edited

@yoni A

Thank you for clarifying your initial question. To try and answer your question more directly, we can refer to the following sections in the User Manual:

First Failure Time

"This picklist returns the time of the first failure. Returning a negative number will cause the first failure to be ignored."

Up Time

"This function determines how long the objects controlled by this MTBF MTTR object will run before they go into a broken-down state. The Up Time is specifically defined as the span between the time that the object resumes from its last down period and the time that it starts its next down period."

Down Time

"This picklist returns the Mean Time To Repair for the objects controlled by this MTBF MTTR object. This function determines how long they will stay in a broken-down state before resuming normal operations again. All of the controlled objects will go back to their original states at the same time."

So, to interpret your input:

1) Your first failure will be at Time = 10.

2) The up and down times for your machine will respectively follow functions "duniform(11160,33120)" and "duniform(600,10800)."

3) This means that your machine will run for a time value between 186 mins. and 552 mins. Then, upon breaking down, the object will be broken down for a time between 10 mins. and 180 mins. Consider this to be a "Mean Time To Repair."

Does this explanation help?

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yoni A avatar image yoni A commented ·

yes it does, thanks @Tanner P

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