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Question on 6 sigma

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  • May 6, 2002 at 7:00 am #29386

    Sachdeva
    ★ 10 Years ★
    Member

    A basic question – If not the only one, one of the definitions of six sigma is 3.4 defects per million.I have seen so many companies following six sigma ranging from Cell phone manufacturer to Aircraft mfg. How can we apply the same standards for all industries ?
    e.g It could happen that an aircraft manufacturer cant affford 3.4 defects per million. so he may need 7 or 8 sigma ?
    corollary of this – are the companies with low accuracy/ precision products spending a lot to maintain a 6 sigma quality ?

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    May 6, 2002 at 8:54 am #75167

    Manu
    ★ 10 Years ★
    Participant

    Vikram,
    you are very right in saying that an aircraft industry would require higher 6 sigma level.
    But in general more industries in US are between 3-4 sigma level. 6 sigma level is a benchmark for those industries to improve their processes to achieve a 6-sigma quality. Since 6-sigma works upon a common basics for all industries like Total units produced, defective units, defects etc and has a systematic process to improve, it can be applied to any industry.
    The companies with low precision/accuracy are not maintaining 6 sigma quality at all and thus their defect level eat into their profits more. So its not a question of spending to maintain quality but the erosion of earnings due to high defect level.

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    May 6, 2002 at 11:26 am #75168

    Dewi Lloyd
    ★ 20 Years ★
    Participant

    Hello
    As far as industries such as aviation are concerned, the way that these issues are dealt with is to build in redundancies as opposed to necessarily achieving phenomenal levels of quality; so if you have a situation where both a normal process and a backup process both have to fail before failure occurs, then exceptional levels of sigma performance are not necessarily needed.
     
    Regards
     
    Dewi Lloyd
     

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    May 6, 2002 at 2:33 pm #75190

    Six Sigma BB Coordinator
    ★ 20 Years ★
    Member

    Some who utilize Six Sigma are not interested in meaning 3.4 ppm at all. We are more interested in Six Sigma methodology and Six Sigma system. Some companies strive for only 3 sigma processes while using Six Sigma approach.
    Then consider how much sigma level you need for your business and use Six Sigma as a tool to go there. You may not want to go to 6 sigma or even want to go beyond 6 sigma. It is up to you.
    Six Sigma Black Belt Coordinator

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    May 8, 2002 at 11:43 am #75257

    RR Kunes
    ★ 20 Years ★
    Member

    You must have a basic knowledge of 6 sigma methodology to ask questions.
    The 3.4 DPMO is a measurement not unlike MPH, or feet per second.
    the mechanism to calculate a sigma value is the methodology you should try to learn more about.

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    May 8, 2002 at 4:26 pm #75270

    Balpreet
    ★ 20 Years ★
    Participant

    Vikram:
    Six Sigma is actually a Problem Solving Tool. Its upto the industry as to what Defect Rate they can live with. Like the NASA people cannot afford a single defect so for them Zero Defect should be the focus.
    Moreover, reaching 6 sigma level is very difficult and is a great challenge for industries.
    Balpreet

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    May 8, 2002 at 8:22 pm #75278

    Martínez
    ★ 10 Years ★
    Participant

    Hello Vikram, Your thinking is on track with Mikel Harry. He said he could compare spark plugs to jet engines. How? DPMO. This means using opportunities for a defect rather than just defectives. e.g. a spark plug may have two or three opportunities for a defect, but a jet engine has thousands. So you would need many spark plugs to compare to one jet engine. Supposedly if you compare DPMO to DPMO everything will have equal footing. There are significant problems with this assumption but I won’t go into that.
     

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    May 8, 2002 at 9:04 pm #75280

    Sambuddha
    ★ 20 Years ★
    Member

    Six Sigma can be understood/perceived at three levels:

    Metric: 3.4 Defects Per Million Opportunities and NOT Defects per million. DPMO allows you take complexity of product/process into account. Rule of thumb is to consider atleast three opportunities for a physical part/component – one for form, one for fit and one for function, in absence of better considerations. Also you want to be six sigma in the Crtical to Quality characteristics and not the whole shebang.
    Methodology : DMAIC/DMADV stuctured problem solving roadmap and tools
    Philosophy : Reduce variation in your business and take customer-focused, data drive decisions.
    I think MBB has pointed out the right points. I just saw a post that pointed out a narrower perspective of Six Sigma than one I am ready to accept. Hence this post.
    Hope that helps.
    Best,
    Sambuddha

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