Demensional Prints or GD&T Prints?

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  • Demensional Prints or GD&T Prints?

    I am working with a lot of Ford prints. Almost everything is dimensionalized. Now with GM the they have what they call GD&T Prints (8x11 sheets)., which on 1 page show all the Datums, One will show the Critical Points, on some they have TP and Profile call outs, and a page with default dimensions. Now my question is, are most of the prints you get are they like Ford or GM.

    Secondly, when ask to do a Cap Study do they request all the dimensioal callouts Like Ford or do the pick out what they want like GM. It amazes me how many the Ford engineers want everything on a print to be capable. Basically they want PPAP Program, to be Capable. Do you think that is over KILL?
    sigpicSummer Time. Gotta Love it!

  • #2
    Re; dimensional / gd&t

    Paul,

    Most prints that I work with gm, chrysler, use gd&t.
    Typically they will have some sc points (special characteristic), and some cc points (critical characteristic).

    These points are what we would perform cap studies on.

    With respect to your Ford engineers, it is ridiculous to expect to perform cap studies on every dimension (definetely overkill).

    Do have engineers at your facility that could talk to the ford engineers, and determine which characteristics are most important, i.e. cc or sc points?

    Regards,
    ZydecoPete
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    • #3
      The Key diff I see is, GM's drawings are in body position. Alex Krulikowski (I believe) used to drive this. He was (is?) the lead dim. eng. Mgr for GM. I think he has since turned it over to someone else. (Alex also drove the rather large GM addendum to the 14.5 standard, and continues to 'sit' on the 14.5 editing committee. )
      I now mostly do tier 2 work for the '3'. So I see a lot of xxx drawings. Those are another story (Sorry J.S.).
      I do however see a lot of CC and SC points, or items designated to be capable per an attribute check. These we also perform cap studies on...
      kb
      RFS Means Really Fussy Stuff

      When all you have is a hammer - everything looks like a nail....
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      • #4
        I am currently working on a Ford part. It is roughly 4 feet long, 8 inches wide, it is the reinf. header for over the 2 side doors. It has 6 SPC points on the fixture (data collector bushings) and that is what we will do the 30-pc study on when it comes time to sell the tools. However, I will also have to do 3 full checks on the parts to show that they are either 100% P.I.S.T. or that what is out is acceptable (deviation allowance write-up / fit and function). However, none of the full check points will have to pass SPC, they just all have to be in tolerance. YES, sometimes the bonehead in charge of buying off the tools have no clue as to what SPC means and what it is really for. We recently sold off a part that was 2.5"x1.5"x0.75". It kind of looked like one of those metal caps you get on fixtures that cover the tooling balls. They wanted 13 SPC points on this part! Heck, the full check was only checking 22 points! The top of the cap was the A-datum (no checks), and hole in the cap was a datum (not checked, on a solid pin and clamp covered it), and a spot on the edge of one of the 'feet' was the other datum. So, no checks on the top of the cap. 2 edge points (with surface) on the side of each foot (6 on each foot, 12 points total) and 2 on the 'vertical' edge of each of the foot-to-cap trim edge (8 points) and 1 surface point on the connector of the 'foot to cap' surface, right in the middle, on each side of the cap. Then, 13 of those were SPC? WAY over-board! I have even had Ford parts in here that had NO spc points. Frame rails, required was 10 full checks (almost 300 points each) with all either in tolerance or acceptable for fit and function, but no SPC.
        sigpic
        Originally posted by AndersI
        I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

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        • #5
          On this part there is a "Dummy Bump" all it is used to is so that the guys on the line know which way to line up and install the unit that assembles into that hole cut out. it is H2.5mm, W4.5mm, L7.5mm, it is on a 52 degree angle from the hole alignmet. Must be capable, so for me to get good readings I must change my tip so that I can get down low enough to get good reading for the width and lenth, I asked if I could use a height gage for the height, it would be faster, and more accurate. Nope, I have to scan the numb, and get the HighPoint.
          sigpicSummer Time. Gotta Love it!

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          • #6
            Tell 'em to scan their own nub!
            sigpic
            Originally posted by AndersI
            I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

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            • #7
              He want my raw data on the cap studies I did on the Radii that he wanted that I used Raduis gages to do. ROFLMAO
              sigpicSummer Time. Gotta Love it!

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