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Topic First DMAIC Project (Manufacturing)

First DMAIC Project (Manufacturing)

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This topic contains 3 replies, has 4 voices, and was last updated by  Chris Seider 9 months, 2 weeks ago.

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  • #698926 Reply

    I’m just about to do my first DMAIC project. I’m doing it as part of a Specialist Diploma in Six Sigma course I’m doing part time in university so the project is not being pushed by the company. I am the one who is leading the project and as such I do not have major resources at my disposal or a black belt to work lean on. From talking to a few people, knowledge of six sigma is not common and from what I see it doesn’t operate in a lean manner.

    I’m looking for some advice on doing a Process Capability study under normal operating conditions. The company I work with manufacture sheet metal parts on laser cutting machines. There are defects associated with the parts due to a variety of reasons including:

    Incorrect part quantities specified or shipped to customer
    Wrong parts shipping to wrong customer (very rare)
    Incorrect material specified
    Rework of parts due to incorrect machine specs
    Downtime due to maintenance/machine problems
    Rush jobs due to defects which effect the schedule and push out jobs resulting in missed delivery dates
    Miscommunication (no communication) between departments
    Sub-optimal cutting files being loaded onto machines

    From reading I have determined that In most cases one will initially perform a Short Term Capability Study whereby one collects approximately 50-75 data points under normal operating conditions. I’m not sure what my data points would refer to in the process that I am working on. In my mind I need to be working with something like a dimension on a part that is being mass produced but given the way the process I am working with operates, there are many different types of parts being produced on the same machine throughout the day.

    Should I be picking one CTQ characteristic and using that as a data point to measure?

    #698964 Reply

    Keep it simple…………

    1. What is the problem you are working on?
    2. What number of parts are being processed?
    3. What number of defects are detected?
    4. What are the root causes of the defects?

    There are important peripheral questions such as how do the defects affect the customer? If you can resolve the problem before it gets to the customer then so much the better. How many parts have multiple defects? Do the high level stuff first and then get down into the detail.

    Just my opinion…………..

    #698967 Reply

    In order to perform Process Capability Study you have to pick up one of the key characteristic/ dimension and perform measurement under normal operation condition, without setting up machine parameters (continuous run in one shift, on one machine).Base on tolerances for specific dimensions (USL, LSL) you have to collect measurement data on one more decimal points, than tolerance required. No. of data points you have specified (50-75) should be sufficient for 95% confidence. Process Capability Study (Minitab, or some order software) will give you Cp/ Cpk ( Pp/Ppk) values, DPMO, which characterize you capability to produce part within 3,4,5 or more process Sigma. Base on customer requirements you will find out, are you meeting or not acceptance criteria. For example: If you achieve required Cp/Cpk value (i.e.1.33) you don’t need to perform 100% of inspection, and you can do statistical measurement of sample size (AQL), which is significant cost savings.

    #698971 Reply

    @andy-parr nice input!

    @donbosco Follow the advice above. One doesn’t just do process capability for a process–one does it for process inputs and/or outputs ONE at a time although product/process sampling can occur with a plan simultaneously.

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