G76: Fine Boring Cycle for Milling
This cycle performs a precision boring operation. Upon reaching the bottom of the hole, the spindle stops at a predefined angle, and the tool tip is retracted from the machined surface before the retract operation is executed.
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Format: |
G76 X_ Y_ Z_ R_ Q_ P_ F_ K_ |
X: Hole position X-axis coordinate
Y: Hole position Y-axis coordinate
Z: Hole bottom coordinate
R: The Z safe rapid descent coordinate
Q: Retraction distance from the surface at the bottom of the hole
P: Dwell time at the bottom of the hole (unit: ms)
F: Cutting feedrate
K: Number of repetitions
Before programming the G76 command, spindle rotation must be activated with an M code.
The M code specified on the same line as the G76 command is executed once during the initial positioning. However, the drilling operation begins without waiting for the completion of the M code. If multiple boring operations are to be performed with the same command, the M code given with G76 is executed only once during the first operation.
To perform the boring operation, one of the X, Y, Z, R, or other axes must be specified as a command.
When programming the G76 code, the R and Q values must be specified in the first line of consecutive G76 commands. These are not mandatory in subsequent boring lines. Since the Q value in the G73 and G83 cycles is used for pecking depth, it should be used carefully when working with the G76 cycle. The previously specified Q value is retained in memory.
When tool radius compensation is active, the G76 code cannot be executed. Before using the G76 code, turn off tool radius compensation with G40. Tool length compensation commands can be used with G76.
Canned cycle commands should not be programmed on the same line as Group 1 G-codes (G0, G1, G2, G3). If they are, the canned cycle commands will be canceled.
For this command to function properly, spindle orientation parameter settings and ladder program implementation must be done. The axis and direction of the retract movement at the hole bottom can be adjusted with PRM314.
Example:
M3 S500 (SPINDLE CW ROTATION)
(PERFORM BORING OPERATION AT X100 Y-250)
(RETURN TO R POINT AFTER BORING OPERATION)
G90 G99 G76 X100. Y-250. Z-150. R10. Q5. P1000 F120.
X200. (2ND DRILLING OPERATION)
Y0. (3RD DRILLING OPERATION)
X100. (4TH DRILLING OPERATION)
G98 Y250. (5TH DRILLING OPERATION)
G80 G53 Z0. (GO TO Z AXIS REFERENCE)
M5 (SPINDLE STOP)