CNC Programming Examples - Drilling

Fanuc G72.1 G72.2 Figure Copy Program Example (Bolt Hole Circle)

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This CNC program example shows how both G72.1 and G72.2 figure copy functions can call one-another in one part program, read Programming Notes below carefully.

Programming

Fanuc G72.1 Rotational Copy

Using G72.1 Rotational Copy G-code a figure specified by a subprogram can be repeatedly produced with Rotational movement.
Read G72.1 definition with program example Fanuc G72.1 Rotational Copy (Figure Copy Function CNC Mill)

Fanuc G72.2 Linear Copy

Using G72.2 Linear Copy G-code a figure specified by a subprogram can be repeatedly produced with Linear movement.
Read G72.2 definition with program example Fanuc G72.2 Linear Copy (Figure Copy Function CNC Mill)

Fanuc G81 Drilling Cycle

G81 drilling cycle is used for simple drilling/spot drilling operations.
Read G81 drilling cycle definition with program examples Fanuc G81 Drilling Cycle

Programming Notes

Specifying two or more commands to copy a figure

1. G72.1 cannot be specified more than once in a subprogram for making a rotational copy (If this is attempted, alarm PS0900 will occur).
2. G72.2 cannot be specified more than once in a subprogram for making a linear copy (If this is attempted, alarm PS0901 will occur).
3. In a subprogram that specifies rotational copy, however, linear copy can be specified. Similarly, in a subprogram that specifies linear copy, rotational copy can be specified.

Fanuc G71.2 G72.2 Program Example

Main program

O4000 ;
        N10 G90 G00 G17 X240. Y230. Z100. ; (P0)
        N20 G72.1 P4100 X120. Y120. L8 R45. ;
        N30 G80 G00 X240. Y230. ; (P0)
        N40 M30 ;

Sub program Rotation copy (G72.1)

O4100 N100 G72.2 P4200 I0 J20. L3 ;
        N200 M99 ;

Sub program Linear copy (G72.2 )

O4200 N110 G90 G81 X120. Y180. R60. Z10. F200. ; (P1)
        N210 M99 ;

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Fanuc G81 Drilling Cycle

G81 drilling cycle is used for simple drilling/spot drilling operations.

Syntax

G81 X... Y... Z... R... K... F...

Parameter	Description
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) .
F	Feedrate.

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.

Usage

            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.

Working

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.

G81 drilling cycle working

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.

Example

            N30 G81 X10 Y30 Z-17 R2 F75
            N40 Y10
            N50 G98 X30
            N60 G99 Y30
            N70 X90
            N80 Y10
            N90 G80

Repeat Drilling

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.

Working Examples

G81 Drilling Cycle Example

            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

G81 drilling cycle usage with G98 G99

            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

Repeat drilling with G81 Drilling Cycle

            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

OR

            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
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Fanuc G82 Drilling Cycle

G82 drilling cycle is also called G82 counter boring cycle.
G82 is a normal drilling cycle the only difference is that it dwell for specified time at the bottom of the hole, normally used for accurate depth drilling.

Syntax

G82 X... Y... Z... R... P... F... K...

Parameter	Description
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.
P	Dwell at the bottom of hole.
K	Number of cycle repetitions (if required) .
F	Feedrate.

Usage

                N30 G82 X10 Y30 Z-17 R2 P1000 F75
                N40 Y10
                N50 X30
                N60 Y30
                N70 G80

Once G82 drilling cycle is specified with it’s parameters in a program block, this will keep drilling at every axis movement, until cycle is ended with G80

Working

How G82 drilling cycle works
1- Rapid traverse to x, y position
2- Rapid traverse to R-plane position
3- Drilling with feed from R-plane to Z-depth position.
4- Dwell for specified time at hole bottom.
5- Rapid traverse to R-plane or Initial-level depends on G99, G98 mode.

G82 drilling cycle working

G98 G99 Modes

How G82 drilling cycle behaves upon G98 or G99 mode,
G98 Drill will return to the Initial level
G99 Drill will return to R-plane.
For a working example see G81 drilling cycle.

Example

                N30 G82 X10 Y30 Z-17 R2 P2000 F75
                N40 Y10
                N50 G98 X30
                N60 G99 Y30
                N70 X90
                N80 Y10
                N90 G80

Repeat Drilling

If K parameter value is given with G82 drilling cycle, then drilling will repeat the number of times given with K. An effective use of repeat drilling is while drilling multiple same distance holes, this way G82 cycle is used in G91 incremental mode. See G81 drilling cycle for repeat drilling example.

Working Example

G82 drilling cycle example

                N10 T1 M06
                N20 G90 G54 G00 X30 Y25
                N30 S1200 M03
                N40 G43 H01 Z5 M08
                N50 G82 Z-10 R2 P1000 F75
                N60 X80 Y50
                N70 G80 G00 Z100 M09
                N80 M30

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