DRILLING CYCLE (G81)

DRILLING CYCLE (G81)

The G81 cycle is intended for drilling.

Program: G81 X~ Y~ Z~ A~ R~ L~

The G81 Cycle is as follows:

  • Step 1: Preliminary canned cycle motion.
  • Step 2: Move the Z-axis only at the current feed rate to the Z position.
  • Step 3: Retract the Z-axis at traverse rate to clear Z.

EXAMPLES

These examples demonstrate how the G81 canned cycle works in detail. Other canned cycles work in a similar manner.

EXAMPLE

The current position is (1, 2, 3), the XY-plane has been selected, and the following line of code is interpreted: G90 G81 G98 X4 Y5 Z1.5 R2.8

This means that it’s in absolute distance mode (G90), old Z retract mode (G98) and the G81 drilling cycle is performed once. The X number and X position are 4. The Y number and Y position are 5. The Z number and Z position are 1.5. The R number and clear Z are 2.8. The following moves take place:

  1. G00 motion parallel to the XY-plane to (4,5,3)
  2. G00 motion parallel to the Z-axis to (4,5,2.8)
  3. G01 motion parallel to the Z-axis to (4,5,1.5)
  4. G00 motion parallel to the Z-axis to (4,5,3)
EXAMPLE

The current position is (1, 2, 3), the XY-plane has been selected, the following line of code is interpreted: G91 G81 G98 X4 Y5 Z-0.6 R1.8 L3

This means that it’s in incremental distance mode (G91), old Z retract mode, and the G81 drilling cycle is repeated three times. The X number is 4, the Y number is 5, the Z number is -0.6 and the R number is 1.8. The initial X position is 5 (=1+4), the initial Y position is 7 (=2+5), the clear Z position is 4.8 (=1.8+3) and the Z position is 4.2 (=4.8-0.6). Old Z is 3.0.

The first move is a traverse along the Z-axis to (1,2,4.8), since old Z < clear Z. The first repeat consists of three moves:

  1. G00 motion parallel to the XY-plane to (5,7,4.8)
  2. G01 motion parallel to the Z-axis to (5,7, 4.2)
  3. G00 motion parallel to the Z-axis to (5,7,4.8)

The second repeat consists of three moves. The X position is reset to 9 (=5+4) and the Y position to 12 (=7+5):

  1. G00 motion parallel to the XY-plane to (9,12,4.8)
  2. G01 motion parallel to the Z-axis to (9,12, 4.2)
  3. G00 motion parallel to the Z-axis to (9,12,4.8)

The third repeat consists of three moves. The X position is reset to 13 (=9+4) and the Y position to 17 (=12+5):

  1. G00 motion parallel to the XY-plane to (13,17,4.8)
  2. G01 motion parallel to the Z-axis to (13,17, 4.2)
  3. G00 motion parallel to the Z-axis to (13,17,4.8)
Example code using G81 cycle:

(Sample Program G81EX18:)

(Workpiece Size: X4, Y3, Z1)

(Tool: Tool #6, 3/4” HSS DRILL)

(Tool Start Position: X0, Y0, Z1)

N2 G90 G80 G40 G54 G20 G17 G94 G64 (Safety Block)

N5 G90 G80 G20

N10 M06 T6 G43 H6

N15 M03 S1300

N20 G00 X1 Y1

N25 Z0.5

N30 G81 Z-0.25 R0.125 F5 (Drill Cycle Invoked)

N35 X2

N40 X3

N45 Y2
N50 X2

N55 X1

N60 G80 G00 Z1 (Cancel Canned Cycles)

N65 X0 Y0

N70 M05

N75 M30

DRILLING CYCLE (G81)