Lmc

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  • Lmc

    I need a good explanation of why I can use bonus on a LMC true position. The customer is telling me I cant do that. Im not sure how to put in words how the cmm does it. Help please
    Attached Files

  • #2
    Originally posted by simcityguy View Post
    I need a good explanation of why I can use bonus on a LMC true position. The customer is telling me I cant do that. Im not sure how to put in words how the cmm does it. Help please

    LMC is just the opposite of MMC. The smaller the ID the more bonus you get & at MMC the larger an ID gets the more bonus.Also look here.

    http://www.tec-ease.com/tips/december-02.htm
    Last edited by bw_bob; 02-16-2007, 04:00 PM.
    sigpic.....Its called golf because all the other 4 letter words were taken

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    • #3
      If LMC is in the FCF you most certainly can use it. If it is not in the FCF then you will most definately lose an argument that you can because it is not implied, never was as far as I know.

      Is this another one of those cases of the supplier educating the customer on his own drawings? Again...........
      <internet bumper sticker goes here>

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      • #4
        Yes I think thats what its turning into. There telling me that if the core is on the larger side I get none.

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        • #5
          Is LMC in the feature conrol frame? Is the feature within the size and orientation specification? If so you can apply LMC as long as you are appling it only to the features that the modifier is attached to. If it is in the feature control frame where your target zone size is specified it is applied to the feature. If it is also on a datum it can be applied to the datum that LMC is attached to. As long as all of your feature's (including datums) size and orientation are good you can aply it. Unless there is something I am missing.
          <internet bumper sticker goes here>

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          • #6
            This is how both TP's look on the print.
            Attached Files

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            • #7
              I was under the impression the larger hole got or the smaller a shaft got
              was least material condition ???????

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              • #8
                Originally posted by BillP View Post
                I was under the impression the larger hole got or the smaller a shaft got
                was least material condition ???????
                MMC = the larger the ID gets the more bonus you get.
                LMC = the smaller the id gets the more bonus you get.
                sigpic.....Its called golf because all the other 4 letter words were taken

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                • #9
                  Originally posted by simcityguy View Post
                  This is how both TP's look on the print.
                  As long as the diameters are in tolerance & not at the max or min range depending if ID or OD then you get bonus tolerance for L in FCF.
                  sigpic.....Its called golf because all the other 4 letter words were taken

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                  • #10
                    The largest hole is LMC as it gets smaller additional positional tolerance can be applied. The smallest shaft is LMC as it gets larger additional positional tolerance can be applied. By the looks of that callout you can apply additional positional tolerance to the feature as it departs LMC. Is there something in particular to your method that they question or just the fact that you are doing it?
                    <internet bumper sticker goes here>

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                    • #11
                      Just the fact that Im doing it, They said if the core is on the larger side even if it is in dim, I dont get LMC I had one part that the TP check .510 and it showed good with LMC and they say I cant do that. Goofy People.lol

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                      • #12
                        bw_bob
                        I went to the url in you'r post and checked term, did I mis-read it ???

                        http://www.tec-ease.com/gdt-terms.htm

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                        • #13
                          Originally posted by BillP View Post
                          bw_bob
                          I went to the url in you'r post and checked term, did I mis-read it ???

                          http://www.tec-ease.com/gdt-terms.htm


                          No you read it correctly. What that means pertaining to LMC
                          The ID...If the hole is at its largest then you get zero bonus, but when it starts getting smaller you start getting extra bonus

                          The OD... The shaft at its smallest gets zero tolerance, but when it starts getting larger the bonus kicks in.
                          sigpic.....Its called golf because all the other 4 letter words were taken

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                          • #14
                            per ASME y14.5-1994

                            2.8.4 Effect of LMC
                            Where a positional tolerance is applied on an LMC basis, the allowed tolerance is dependent on the actual mating size of the considered feature. The tolerance is limited to the specified value if the feature is produced at its LMC limit of size. Where the actual mating size of the feature has departed from LMC, an increase in the tolerance is allowed equal to the amount of such departure. The total permissible variation in position is maximum when the feature is at MMC, Likewise, referencing a datum feature on an LMC basis means the datum is the axis or center plane of the feature at the LMC limit. Where the actual mating size of the datum feature has departed from LMC, a deviation is allowed between its axis or center plane and the axis or center plane of the datum.

                            hope this helps ya
                            Which one gets ridden today? MPH vs MPG..tough choice, both are FUN
                            sigpic

                            Starrett RGDC 4028-24 :alien:
                            Demon vintages 3.7, 4.1, 4.2, 4.3, 2009

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                            • #15
                              Typical use of MMC is the larger the hole (within tolerance) the more tolerance you get.

                              Typical use of LMC is the smaller the shaft (OD), again within tolerance, the more tolerance you get.

                              My take on it,

                              TK
                              sigpicHave a homebrew

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