Controlling Threading Infeed Angle with Fanuc G76 Threading Cycle



Briefly described how to control thread infeed angle while machining threading on a cnc machine with fanuc cnc control.

You better watch the video ( Thread Infeed Tips from Sandvik Coromant a Video ) which briefly describes the difference of thread infeed angles and benefits and weaknesses of different thread infeed angles.

Fanuc G76 threading cycle gives us full flexibility to thread the way we like.

Fanuc G76 Threading Cycle

N5 G76 P010060 Q100 R0.05
N6 G76 X30 Z-20 P1024 Q200 F2
Controlling Thread Infeed Angle with Fanuc Threading Cycle G76

Controlling Thread Infeed Angle with Fanuc Threading Cycle G76

G76 : Threading Cycle Parameter P P actually consists of multiple values which control the thread behavior,

  • 01 : Number of spring cuts, you can change it at your will.
  • 00 : Thread run out at 45 degree
  • 60 : Thread Infeed Angle / Flank angle

All the parameters of Fanuc threading cycle G76 are fully explained here. The values with P are actually 03 pairs of values, the last pair is to control the thread infeed angle of each pass for threading, You can see the bold line above with value 60.

G76 Threading Cycle with 60 Degrees Infeed Angle for 60 Degree Threads (Compound Infeed/ Flank Infeed)

If you put 60 for the infeed angle, this will put most of the load on the front edge of the threading insert.

G76 Threading Cycle with 55 Degrees Infeed Angle for 60 Degree Threads

If you put 55 for the infeed angle for the standard 60 degree threads, this will put most of the load on the front edge or leading edge of the threading insert and will also put a small load on the back edge of the threading insert.

G76 Threading Cycle with 0 Degrees Infeed Angle ( Radial Infeed)

If you put 0 for the infeed angle, this will put the load on the full profile of the threading insert.

Square thread always need a straight radial infeed (plunge infeedĀ ).

G76 Threading Cycle Recommended Infeed Angles

The following indeef angles should be used as infeed angles with G76 fanuc threading cycle. 80, 60, 55, 30, 29, 00


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