
PROGRAMMING
B–63124EN/01
14. FUNCTIONS TO SIMPLIFY
PROGRAMMING
163
WARNING
1 Neither T code nor M code should be commanded in G75
block.
2 The repositioning amount of the workpiece holder is
specified by a numerical value following address X in G75
command. If repositioning is made in the +X direction of the
work coordinate system, specify it by a positive numerical
value.
3 Other M codes may be used for M10 and M11 depending
upon machine tool builders.
4 Programming is made, assuming that the workpiece is fixed
and a tool moves along the workpiece.
However, the workpiece moves, while the tool is fixed
generally. Accordingly, the movement direction of the
workpiece, or, the movement direction of the workpiece
holder, is contrary to the movement direction of the tool.
This means that, when the workpiece holder moves in the
+X and +Y directions of the work coordinate system, the tool
must be regarded to move in the –X and –Y direction
respectively. Accordingly, the command in (2), (3), (4)
blocks is opposite to movement direction in the work
coordinate system of the workpiece holder.
5 In G75 command, the relief quantity of the workpiece holder
from the workpiece is equal to the return quantity of the
workpiece holder to the workpiece in the absolute value of
its movement amount.
However, if a workpiece is uneven, the workpiece holder
depresses the workpiece, causing the workpiece to be
deviated, assuming that the workpiece holder returns by the
relief quantity as it is.
For such a work, change the relief quantity and return
quantity by the following programming.
M10;
G91Y y
1
;
X –x
;
Y –y
2
;y
1
differs from y
2
.
M11;
Even in the above command, internal processing is made
in NC so that the tool position remains unchanged in the
work coordinate system, irrespective of the movement of
the X and Y axes.
Accordingly, it is not necessary for programming to take this
movement into consideration in the subsequent
commands.
However, since the workpiece cannot be held if such a
command is given again, it is necessary to take these
circumstances into consideration when performing
repositioning again.
6 It is not recommended for cycle time and machining
accuracy to repeatedly execute repositioning by a program.
7 The single block stop is made after five sequential motion,
if G75 is executed by a single block operation.