Program Mode vs Iterative Alignment

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  • Program Mode vs Iterative Alignment

    I have always used "Iterative" alignments to marry part model with program and have been very successful. What are the rules for using "Program Mode"? And why would one use "program mode" as oppose to "iterative" alignments?

  • #2
    Prismatic Parts

    If your parts have square faces and well defined datums, then Program Mode alignments are simple enough.

    If your parts are contoured surfaces with no flat sides nor square corners, then iterative alignment is the way to go.

    You can also use iterative alignments in prismatic parts (1st paragraph) but it is your choice.


    • #3
      I concurr with what Don had said and in addition, there is another reason for choosing to go the "program mode" route (also sometimes referred to as basic 3-2-1 alignment mode).

      If you have no model to work with or the model is corrupt or otherwise unusable, and if the part as Don stated, has "well define datums", then a program mode alignment is the way to go. It is also in some cases more preferred in that the program mode doesn't take nearly as long to establish it's alignment.
      Thomas Stewart
      Quality Technician/CMM Programmer

      2010 MR1
      Mitutoyo BN715
      CMMC-3 Controller


      • #4
        Gentlemen-Thanks for your input.


        • #5
          We find that different axes often have different datum points so we use program alignments quite frequently. If anybody has any ideas how to get iterative alignments to do that or if they do that by default please let us know


          • #6
            Different Axes?

            I suspect by this you mean that the Z datum is not always the top of the part?

            In the ierative alignment dialog, when you select the first 3 points, instead of AUTO you can select which plane this represents. Is this what you are referring to?


            • #7
              not exactly, often the level item will be a datum for one axis. the rotate item a datum for another and a single point the datum for the third axis. no one measured point is the datum for all three axis. I suspect our engineers might be a little distrustful of a constructed datum point


              • #8

                I'm not sure I understand the problem then. What you describe is how the iterative alignment should work now. The level points set the datum for one axis, the rotation points another axis, and the origin point is only used for the final axis. Some of this depends on which types of features you use though. . .


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