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Defect Vs Defective for DPMO Calculation

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  • #51234

    Perera
    Member

    Hi,
    I have started using six sigma concepts and i have one basic question on the DPMO calculation.
    If we are taking the defect as base for DPMO. How can we define that defect and how it is different from defective.
    Can any one help me out

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    #177275

    Clive
    Participant

    How I take this and I’m not saying I’m right is that if your final product has 10 ways of being wrong and your measuring each of these then your measuring defect, (10 opps) but if you say well that it’s either good or bad then your measuring defectivies (1 opp).
    In my opinion measuring defectivies measures what the customer feels so is the better of the two. Defects can easily be used to make your system look a lot better than it is by adding in a couple of opps which never fail.

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    #177277

    Perera
    Member

    Rejections in Nos
     
    Base Line Sigma

    Stage 1 Loss 
    Stage 2 Loss
    Customer Returns
    Total
    Production Qty
    Loss Percentage
    DPMO
     Short Term
    Long Term

    DPO

    Case 1
    Apr’08
    9383
    13523
    0
    22906
    243116
    9.42
    94218
    2.8
    1.3

    Case 2
    Apr’08
    9383
    13523
    0
    22906
    243116
    9.42
    7851.53
    3.9
    2.4
    In case 1 i have taken PPM
    In case 2 i have considered 12 types of difects can occur in any of this defect products.

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    #177284

    Pramod
    Participant

    Suresh,
    A unit of product may have many types of defects. Any one non-confirmity is a “defect” and a unit with a defect or many defects is called a “defective” unit. This is the fundamental difference between defect and defective. For example, one product has only one defect, that product is a defective unit-more than one defect in one product is also called a defective unit. For DPMO calculation you need to consider no. of defects in each unit.
    Best Regards,
    Pramod

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    #177286

    Pramod
    Participant

    DPMO = DPU x 1,000,000

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    #177301

    Mike Carnell
    Participant

    Suresh,You haven’t gotten a correct answer yet.Good luck

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    #177313

    Perera
    Member

    We are producing components and having 4 stage process the product will be rejected due to 12 types of defects ( all type of defects will not be present in one rejeced sample)
    Total Productin Qty – 4,18,534
    Total Rejected Qty – 22210 
    Total types of defects considered 12
    DPO = {22210/(418534×12)} = 0.44
    DPMO = DPO x 1000000 = 0.44 x 1000000 = 440000
    Is it Ok
     

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    #177322

    Pramod
    Participant

    Suresh,
    What is your Y?
    Pramod

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    #177323

    Mike Carnell
    Participant

    Suresh,You need to use your head and think about the advice you are getting. If you want to use DPMO then you need to start with the number of opportunities you have. It has nothing to do with the possibilies to makes types of errors. It is the opportunities to do something correctly. The simplest calculation and is somewhat conservative is parts plus connections.Going from Number of opportunities it should be pretty straightforward to calculate defects per opportunity (DPO) and if you want DPMO you multiply by……It doesn’t have anything to do with DPU or what your Y is.You need to think about what the words mean and stop being a sucker for such crappy advice. You should be able to figure this out for yourself.Good luck.

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    #177338

    Mikel
    Member

    Use a “c” chart for the number defective.
    Use a “u” chart for the number of defects.
    There’s volumes on the net explaining these two charts.
    … ooops … but neither of these have anything to do with “six sigma” defects and six sigma’s “sigma” can’t be used either !!!!
    Anyone who believes in “3.4 defects” needs his head examined.
     
     

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    #177339

    Thilanka Marasinghe
    Member

    Hi,
     
    Can anybody propose us a good theme/slogan for our company six sigma community 
     
    TM

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    #177340

    Hiro
    Participant

    Stan,
    if your actual process is free of any shifts and is perfectly normal it produces 0.002 defects

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    #177342

    Craig
    Participant

    Sick Sigma
    Opporunity count inflaters
    Deming Slogan Committee
    Just a few options
     

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    #177346

    Sridhar Sukumar
    Member

    Hi Suresh,
    Assume you are a manufacturer of Gear Box with 10 gears in it. If you supply this gear box to a car or a stationary machine you treat failure of individual gears seperately so defects(DPMO) is what you see. If you supply this gear box to an Aeroplane, the criticality of each gear is high so any failure would be equal to failure of the gear box, the entire unit. Here it is defective(DPU).
    Regards
     

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    #177352

    Jonathon Andell
    Participant

    I’ve always been fond of “Old Hat, New Feathers.”

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    #177359

    will
    Participant

    Suresh,
    Send me your email address. I will send you an Excel file which shows the difference between a DPMO calculation and a defective calculation (Yield).
    Cyrus

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    #177473

    Perera
    Member

    Dear Cyrus,
    Here is my E mail ID :
    [email protected] 
    [email protected]
    Suresh

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