Calculate Reliability of a machine with use of failure rate (Weibull)

[koen91]

Hi all,

This is my first post. Had a question regarding a calculation i am trying to make regarding the reliability of machine. I have done this before but can't figure out how I did it I attached the file with the calculations I made previously (I only included the first 20 data inputs in order to keep it clean)
I got the failure times of the machine and I want to end up with a Weibull graph showing the reliability of that machine.

What I remember so far is that you need to:
1. calculate time between failures (column E)
2. Determine probability (Column H)
3. Create Timesteps (Column M)
4. Determine another time till next failure (Column N)
5. Determine likelihood (Column P)
6. Log likelihood (Column q)
7. Determine reliability (R(t)) and failure rate (F(t))
8. Graph R en F

However I can't seem to recall how to determine step 4 and excel does not show any calculations. Therefore it is impossible to do the other steps as well
I have been looking on the internet but can't seem to find anything. If anyone could help me that would be greatly appreciated,
Thanks in advance!

Kind regards

Koen

[loginjmor]

Hi -

This isn't so much an Excel question as it is a statistics question concerning Weibull distributions and analyses.

I looked at your data, briefly and graphed the Time to Next Failure, and it is not linear data. It has an upward trend, but I can't figure out how those numbers were determined. I'm not sure if they're tied to the time step increments, or what those time increments represent. Percent of days? I have no idea.

I think you will need to search for and study Weibull Distribution testing and follow the procedure to come up with your desired outcome. To my knowledge, there is no Excel function or guidance to do this for you.

[koen91]

Cheers , thanks for your help. I couldnt figure that out myself either but I ll take a look at Weibull procedure