Numerical Control Programming
Chapter 2
How Does Numerical Control Work?


Review Questions

  1. What is the function of an N/C program?
  2. N/C programs always assume the cutting tool moves around the workpiece even though the the workpiece actually moves around the tool. (T / F )
  3. Name the three axes of motion in an N/C mill.
  4. Name the axis that moves right and left on a vertical spindle N/C mill.
  5. Name the axis that moves toward and away from the operator on a vertical spindle N/C mill.
  6. Name the axis that moves toward and away from the operator on a horizontal spindle N/C mill.
  7. Name the axis that is parallel to the spindle on an N/C lathe.
  8. Name the axis that doesn't exist on an N/C lathe.
  9. Explain what an "origin" is and how its location is determined.
  10. The two N/C positioning methods are _____________ and _______________.
  11. N/C commands that stay in effect until changed or canceled are said to be _________________.
  12. One-shot N/C commands are said to be ___________.
  13. What is a group of N/C commands that is similar to an English language sentence called?
  14. Describe the function of the EOB character.
  15. Which key on the keyboard or data-entry terminal usually generates the EOB character?
  16. Which N/C format has the characteristic that every block must have exactly the same number of characters.
  17. Which N/C format has the characteristic that unneeded command data can be "skipped over?"
  18. The special-purpose electronic "pigeon holes" in an N/C controller that store command data are called ___________.
  19. List the more commonly used address words and describe their functions.
  20. Explain the significance of each group of characters in the following EIA-274-D data format specification:
        N4.0 G2.0 XYZIJK2.4 F2.1 S4.0 M2.0
  21. To what does EIA refer?
  22. To what does EIA-274-D refer?
  23. Describe the purpose of tool length offsets (TLOs).
  24. Describe how TLO data are loaded into a TLO register.
  25. When writing a program for an N/C machine that has no TLO registers, how does a programmer account for the difference in length of the various cutting tools?
  26. Describe how the controller executes a subroutine.
  27. Describe what a loop does in an N/C program.
  28. Describe the three "elements" that must be present in an N/C program loop.
  29. Describe "nesting" of loops and subroutines.
  30. Describe the three essential N/C programming elements.
  31. The three factors used to calculate an IPM feedrate for an N/C machining operation are
    1. _________,
    2. _________, and
    3. _________.

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Updated Jan. 9, 2002
Copyright 1988-2002 by George Stanton and Bill Hemphill
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