G81 drilling cycle is used for simple drilling/spot drilling operations.
G81 X... Y... Z... R... K... F...
|X||Hole position in x-axis.|
|Y||Hole position in y-axis.|
|Z||Depth, tool will travel with feed to Z-depth starting from R plane.|
|R||Position of the R plane.|
|K||Number of cycle repetitions (if required).|
Once G81 drilling cycle is defined, the canned cycle is repeated at every X-Y position in sequential blocks. So G81 drilling cycle must be cancelled with G80.
N30 G81 X10 Y30 Z-17 R2 F75 N40 Y10 N50 X30 N60 Y30 N70 X90 N80 Y10 N90 G80
In the above example drilling will start with G81 drilling cycle at X10 Y30, so first drill will be at X10 Y30, then second at Y10, third at X30, fourth at Y30, fifth at X90 and the last one at Y10, because next block have G80 code, so drilling cycle will no more be repeated.
Here is briefly described how G81 drilling cycle operates,
1- Rapid traverse to the specified x,y axis position (drilling position).
2- Rapid traverse to the R plane position.
3- Drilling with specified Feed from R-plane position to Z-depth position.
4- Rapid traverse to Initial level or R-plane depends on G98, G99 modes.
G98 G99 Modes
After completing drilling depth the return is made with Rapid feed, the return height can be controlled through using G98 or G99.
G98 Drill will return to the Initial level
G99 Drill will return to R-plane.
G98, G99 can be used multiple times during G81 drilling cycle.
N30 G81 X10 Y30 Z-17 R2 F75 N40 Y10 N50 G98 X30 N60 G99 Y30 N70 X90 N80 Y10 N90 G80
With G81 drilling cycle drilling operation can be repeated multiple times. The drilling is repeated K times when that parameter is given with G81 drilling cycle.
Repeat drilling is normally used with G91 Incremental mode, and a good example of repeated drilling is Grid-plate drilling. the example for repeat drilling is given below.
N10 T1 M06 N20 G90 G54 G00 X30 Y25 N30 S1200 M03 N40 G43 H01 Z5 M08 N50 G81 Z-10 R2 F75 N60 X80 Y50 N70 G80 G00 Z100 M09 N80 M30
G98 G99 Example
N10 M06 T1 N20 G90 G00 X12.5 Y10 Z12 S1000 M03 N30 G99 G81 X12.5 Y10 Z-17 R2 F75 N40 Y30 N50 G98 X57.5 N60 G99 Y10 N70 G91 G80 G28 X0 Y0 Z0 M05 N80 M30
Repeat Drilling Example
T1 M6 G00 G90 G40 G21 G17 G94 G54 X0 Y0 S1000 M03 G43 H1 Z100 Z3 G81 G99 G91 X20 Y20 R3 Z-20 K3 F100 M08 G80 G00 G90 Z100 M30
T1 M6 G00 G90 G40 G21 G17 G94 G54 X20 Y20 S1000 M03 G43 H1 Z100 Z3 G81 G99 R3 Z-20 F100 M08 G91 X20 Y20 K2 G80 G00 G90 Z100 M30