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author's profile photo Former Member
Former Member

Reg:MTBF Calculation

Posted on Nov 28, 2012 at 08:48 AM 412 Views

Hello Experts,

My client needs to have MTBF Formula which is to be customized .The formula used is MT BF = total no of machines(total available hours-total B/D Hours)/total number of B/D 's.

But in standard SAP there is ONLY MTBR Formula which is not same as MTBF. i WANT To know from where we take total B/D Hours for the formula from MCJB Report we are getting output for total b/d hours .but its difficult for me to find wher the data is getting stored to calculate for the formulae.

Can any body show more light or possible suggestions for calculating MTBF or can we derive the formulae from MTBR.

REGARDS,

SATISH.

PLM Enterprise Asset Management (EAM)/Plant Maintenance (PM)
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5 Answers

  • Best Answer
    author's profile photo Former Member
    Former Member
    Posted on Nov 28, 2012 at 09:57 AM

    Hi Satish,

    What I understand is if MTBF=total uptime / no of breakdowns, then its is equivalent to MTBR.

    So u can take MTBF =MTBR in SAP (T code MCJB /MCI7)

    Regards,

    Ebin

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    • Former Member Former Member
      Nov 29, 2012 at 03:18 PM

      Hi Satish,

      As per ur formula MTBF = total no of machines(total available hours-total B/D Hours)/total number of B/D 's.

      Total number of breakdowns /total avaialble hours / total down time for ur client means sum of no of breakdown of all equipments available/ total available hours of all equipments /total down time of all equipments?

      If thats the case the formula looks strange.U cant derive it from MTBR of SAP.U need to go for development.

      regards,

      ebin

  • author's profile photo Former Member
    Former Member
    Posted on Nov 28, 2012 at 09:07 AM

    Hai Sathish

    MTBF=Sum of up time periods / number of uptime periods

    Suppose our widget machine is scheduled to run nonstop for 480 minutes. Instead, it runs 63 minutes, jams and goes down for 16 minutes, runs 102 minutes, blows a fuse and is off line for 30 minutes, then runs 200 minutes before smoking a belt and going down for the rest of the shift. The MTBF would be calculated as 63 Minutes + 102 Minutes + 200 Minutes ÷ 3 Occurrences = 121.7 Minutes MTBF

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  • author's profile photo Former Member
    Former Member
    Posted on Nov 30, 2012 at 04:29 AM

    Hi Satish,

    The std. formula for calculating MTBF is

    MTBF = MTTR + MTBR

    Please check at your end, may be helpful to you....

    Regards

    Ritesh

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  • author's profile photo James Prabaharan
    James Prabaharan
    Posted on Nov 30, 2012 at 05:23 AM

    Hi,

    Please go through the following link to know SAP calculations on MTTR and MTBF.

    http://help.sap.com/erp2005_ehp_06/helpdata/EN/c1/37699d449a11d188fe0000e8322f96/content.htm

    James Prabaharan

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  • author's profile photo Akhilesh Singh
    Akhilesh Singh
    Posted on Nov 28, 2012 at 11:02 AM

    Hi Satis,

    As per MTBF/MTTR calculation:-

    MTBF = Mean Time Between Failures

    To calculate MTBF, use this formula:

    MTBF = Total uptime for a period of time / number of stops during the same period

    In other words, MTBF is the average time between downtime periods. For example, if during a week of production you have 30 hours of uptime and 10 stops then the MTBF would be 30 / 10 = 3 hours.

    MTTR = Mean Time to Repair

    To calculate MTTR, use this formula:

    MTTR = Total downtime for the same period as used for MTBF / number of stops

    Put simply, MTTR is the average time of a failure. For example, if during a week of production you have 10 hours of downtime and 10 stops then the MTTR would be 10 / 10 = 1 hour.

    And you can take this report from TC- MCJB/MCI7

    Regards,

    Akhilesh

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    • Former Member
      Nov 29, 2012 at 01:52 PM

      hi, akilesh

      MTBF and MTBR Formulae is not same.pls see MTBF Formulae used by my client in my post and compare with MTBR std formulae.

      satish