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Capability On Rolled Product

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  • #43769

    Fontanilla
    Participant

    Hello-  I am new to the world of quality and 6 Sigma
    I work for a rolling mill.  We need to provide process capability on our product.  Because the line produces a continous line of product we do not have indivdual parts.  In this case, how do I subgroup?  We normally cut a length of product (10-20 feet) and take 100 measurements along the length of that bar.  Would this mean I have a subgroup of 100 or 1?  I am confused on how to most accuratly analyze this capability. 
     
    Dan

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    #139308

    Anonymous
    Guest

    Dan,
    Continuous webs are typically multivariate processes – other examples include float glass, large silicon wafers, and film handling systems.
    My approach would be to use exploratory data analysis and process engineering knowledge to try and understand the sources of variation.
    Once you’ve found this out you can test the stability of the process over time using one chart for the process mean and another for the process uniformity.
    Regards,
    Andy

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    #139695

    melvin
    Participant

    How often do you take the sample of 10-20 ft?
    In thinking of subgrouping – what variation do you want to view as common cause / noise & what variation as special cause? 
    Are you interested in viewing the macro sample as the subgrouping level or in looking within the macro sample.
    Exploratory data andlysis &/or using existing knowledge in combination with the objective of your study will help establish the answer for you. 
    Bob
     

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