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Edge of limits in the DoE

Discussion in 'DOE - Design of Experiments' started by leomac83, Aug 22, 2019.

  1. leomac83

    leomac83 Member

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    Hi,
    I've just started to study the QbD, so what I understand is that the QTPP is what matters to the actual user including the doctors and the patients. Clinical studies and CQAs is what matters to the manufacturers, what we test at the end before we ship the product out.

    So my question is, numerically speaking, are the edge of limits of the DoE the tolerance values of the QTPP and CQA parameters?

    Thanks in advance.
     
  2. Miner

    Miner Moderator Staff Member

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    Please spell out all of your acronyms. You have so many acronyms that the question is unclear.
     
  3. leomac83

    leomac83 Member

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    ? OK ...
    QbD = Quality by Design
    CQA = Critical Quality Attribute
    QTPP = Quality Target Product Profile
    DoE = Design of Experiment
     
  4. Miner

    Miner Moderator Staff Member

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    Thank you. I better understand your question, but cannot find any information regarding "edge of limits". The rest of the Quality by Design material makes sense. It appears to be a version of Design for Six Sigma with different acronyms. What is meant by edge of limits? Could this be "edge of failure"?

    Edge of Failure is the boundary to a variable or parameter, beyond which the relevant quality attributes or specification cannot be met. The edge of failure is the farthest Design Space modeled boundary beyond which a QbD specification criterion cannot be met, even with the adjustment of orthogonally linked and offsetting process parameters.

    If you intended edge of failure, this means the extreme process (input) variable settings (typically found by DOE) that would result in the CQA (output) crossing the QTTP tolerance.
     
    Last edited: Aug 22, 2019
  5. leomac83

    leomac83 Member

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    Yes, sorry my mistake with the translation. I meant Edge of Failure.

    Could you be a little clearer? I can't understand what you mean.
     
  6. Miner

    Miner Moderator Staff Member

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    A process converts inputs into outputs. A CQA is an output of the process. Changes in inputs result in changes in outputs as well as changes in a CQA. There will be an input setting such that the output (CQA) will no longer meet the requirements of the QTPP. This input setting is an Edge of Failure. A DOE is an efficient tool for identifying these Edge of Failures.
     
  7. leomac83

    leomac83 Member

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    Perfect but practically talking, the edge of failure is a range of numbers, a tolerance of the input setting. Input settings = CMA (Critical material attribute) and CPP (critical process attribute).

    For example, if the CPP is the temperature 30°C, the edge of failure is the +- 1°C.

    Is it right?
     
  8. leomac83

    leomac83 Member

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    CPP = Critical process PARAMETERs
     
  9. Miner

    Miner Moderator Staff Member

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    That is my understanding.
     
  10. leomac83

    leomac83 Member

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    Ok, thank you very much
     

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