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Thread: root cause analysis-advice for eliminating diameter variations in cnc turning centres

  1. #1
    Associate Engineer
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    Post root cause analysis-advice for eliminating diameter variations in cnc turning centres

    Im doing my final year project on root cause analysis in a cnc industry.

    After receiving the rejection details we made a pareto chart and found out the main problem as the variation of diameters both ID & OD.

    We were able to list out few causes and we are struck up after that.

    I need some advices on how to proceed like the possible causes for diameter variation and commonly available solutions for elimination...request you people to guide me..
    Last edited by Kelly Bramble; 02-13-2013 at 01:39 PM. Reason: Punctuation

  2. #2
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by seenu1905 View Post
    I need some advices on how to proceed like the possible causes for diameter variation and commonly available solutions for elimination...request you people to guide me..
    The following come to mind..

    Internal stress/strain within the material
    Worn out machinery
    Worn out tooling
    Thin Wall design
    Aggressive materials removal
    Target tolerance structures out of manufacturing process capability

  3. #3
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    Depending on the tolerances desired, the stability of the machine tool castings during ambient temperature swings can play a big part. I know HAAS offers some machines with active cooling systems running through the bases. They have a small refrigeration unit that circulates coolant throughout the machine structure to keep tight tolerances.

    Back in the days of Jig Borers, the German and Swiss machines were legendary for temperature offsetting systems that were all completely mechanical.

    Vibration on a turning center should be something easily included in the design phases and not show up as a problem during production. Go look at a Monarch or Hardinge for vibration free operation. I cannot see it being a problem if the machine is designed and manufactured correctly.

  4. #4
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    is there any possibility of giving temperature compensation through cnc programs??? im on my way of learning cnc programming..

    we are also planning to recommend the usage of collet chucks instead of 3 jaw chucks..your comments on that???

  5. #5
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    You need to think about this some more instead of just asking. That's just plain lazy. Give the temperature compensation via GCode some serious thought and them come back an d ask questions based around your reasoning. Life is not about getting your work done by others.

    Again, YOU need to do some research on the difference between collets and chucks and why they are different and why both have their places in the machine shop.

    I am sure I speak for all of the regulars here when I say, we are more than willing to keep you on the right track with the thinking but we are not going to do the thinking for you. Take another quick read of my signature...

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