Internal threading is a critical process in CNC machining, allowing for the creation of detailed threads inside a bore. The Fanuc G76 threading cycle is a two-line command widely used for this purpose, offering precision and repeatability.

Usage Format

The G76 threading cycle is initiated by specifying the threading parameters across two lines of code:

G76 P010060 Q100 R0.05
G76 X Z P Q F R E K

• P defines the thread depth, clearance, and angle.
• X and Z denote the final thread dimensions.
• Q sets the thread start angle.
• F is the thread pitch.
• R specifies the last thread height.
• E controls the thread taper amount.
• K determines the number of thread passes.

Explanation

The G76 cycle automates the threading process by calculating the necessary cuts. The first line sets up the cycle, while the second line dictates the threading specifics. The control uses these parameters to execute precise, consistent threads.

Example

Let’s create an M6 thread with a pitch of 1mm inside a bore:

G76 P010060 Q100 R0.05
G76 X6.0 Z-12.0 P1000 Q150 F1.0 R0.01 E0 K9

Text Diagram:

|-----------------|
|                 |
|                 | <- Start of bore
| ***             | <- Thread start
| ***             |
| ***             | <- Thread depth
|                 |
|                 | <- End of bore
|-----------------|

In this example, the G76 cycle will produce an M6 thread with a 1mm pitch, starting 15 degrees from the top of the bore and making 9 passes to achieve the final thread depth.