computer numerical control programming basics - Industrial Press

Fig. 6 A workpiece dimensioned in the incremental system mode. (Icon Corporation)
• A “X plus” (X+) command will cause the cutting tool to be
located to the right of the last point.
• A “X minus” (X-) command will cause the cutting tool to be located
to the left of the last point.
• A “Y plus” (Y+) command will cause the cutting tool to be
located toward the column.
• A “Y minus” (Y-) will cause the cutting tool to be located away
from the column.
• A “Z plus” (Z+) command will cause the cutting tool or spindle
to move up or away from the workpiece.
• A “Z minus” (Z-) moves the cutting tool down or into the workpiece.
In incremental programming, the G91 command indicates to the
computer and MCU (Machine Control Unit) that programming is in
the incremental mode.
Absolute program locations are always given from a single fixed
zero or origin point (Fig. 7). The zero or origin point may be a
position on the machine table, such as the corner of the worktable
or at any specific point on the workpiece. In absolute dimensioning
and programming, each point or location on the workpiece is given
as a certain distance from the zero or reference point.
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