Programming of CNC Machines. Ken Evans

cycles E User Macro Character F Feed rate; (Turning) Precise designation of thread lead G Preparatory Function H Tool Length Offset number I Incremental X coordinate of circle center; (Turning) parameter of fixed cycle J Incremental Y coordinate of circle center K Incremental Z coordinate of circle center; (Turning) parameter of fixed cycle L Number of repetitions (subprogram, hole pattern); Fixed offset group number M Miscellaneous Function N Sequence or block number O Program number P Dwell time, program number, and sequence number designation in subprogram; (Turning) Sequence number start for multiple repetitive cycles Q Depth of cut, shift of canned cycles; (Turning) Sequence number end for multiple repetitive cycles R Point R for canned cycles, as a reference return value; Radius designation of a circle arc; Angular displacement value for coordinate system rotation S Spindle-Speed Function T Tool Function U Additional linear axis parallel to X-axis V Additional linear axis parallel to Y-axis W Additional linear axis parallel to Z-axis X X coordinate Y Y coordinate Z Z coordinate

COMMON SYMBOLS USED IN PROGRAMS
SYMBOL	MEANING
–	Minus Sign, Used for Negative Values
/	Slash, Used for Block Skip Function
%	Percent Sign, Necessary at program beginning and end for communications only
( )	Parentheses, Used for comments within programs
:	Colon, Designation of Program Number
;	Semicolon, End-Of-Block character
.	Decimal Point, Designation of fractional portion of a number

Part 1 Study Questions

      1. Programming is a method of defining tool movements through the application of numbers and corresponding coded letter symbols.

      T or F

      2. A lathe has the following axes:

      a. X, Y, and Z

      b. X and Y only

      c. X and Z only

      d. Y and Z only

      3. Program coordinates that are based on a fixed origin are called:

      a. Incremental

      b. Absolute

      c. Relative

      d. Polar

      4. On a two-axis turning center, the diameter controlling axis is:

      a. B

      b. A

      c. X

      d. Z

      5. The letter addresses used to identify axes of rotation are:

      a. U, V, and W

      b. X, Y, and Z

      c. A, Z, and X

      d. A, B, and C

      6. The acronym TLO stands for:

      a. Tool Length Offsets

      b. Total Length Offset

      c. Taper Length Offset

      d. Time Length Offset

      7. When referring to the polar coordinate system, the clockwise rotation direction has a positive value.

      T or F

      8. In Figure 1-17, in which quadrant is the part placed?

      9. A program block is a single line of code followed by an end-of-block character.

      T or F

      10. Each block contains one or more program words.

      T or F

      11. Using Figure 1-15, list the X and Y absolute coordinates for the part profile where Workpiece Zero is at the lower left corner. (The corner cutoff is at a 45° angle.)

      12. Using Figure 1-15, list the X and Y incremental coordinates for the part profile where workpiece zero is at the lower left corner.

      13. How often should the machine lubrication levels be checked?

PART 2

       CNC MACHINE OPERATION