Facing Cycle in Fanuc Control G72 or Transverse Roughing Cycle
Programming format:-
Not only can we rough turn along the Z-Axis using the G71 roughing cycle we can also rough turn on the X-Axis using the G72 facing cycle. The G72 works in much the same way as the G71 but cuts in a facing direction towards the center line of the part.
What is the G72 facing cycle?
With this cycle, the tool will cut along the X-Axis towards the centerline of the component. This is used when we wish to turn a spigot at the front of the part or that we wish to remove material in that direction. The cycle will follow the contour of the profile by using a subroutine that we place between 'N' numbers then recall that subroutine using the G72 command. Finishing allowances are added by using 'U' and 'W' to leave material on for a finishing pass that will clean up the surface of the part.
G72 facing roughing cycle
G72 facing cycle on a CNC lathe
The G72 cycle uses two lines of G-Code to tell our Lathe how we wish the cycle to perform. Some machines may use the one line version that I mention at the end of this article
Each command or word in these two lines are broken down and explained below.
G72 W(1) R;
G72 P Q U W(2) F;
G72 - FACING CYCLE
W(1) - DEPTH OF CUT
R - RETRACT VALUE
P - FIRST LINE OF SUBROUTINE
Q - LAST LINE OF SUBROUTINE
U - AMOUNT LEFT ON FOR FINISHING IN ANNOUNCEMENT
W(2) - AMOUNT LEFT ON FOR FINISHING IN Z
F - FEED RATE
G72 is our G-Code that tells the machine that we wish to use the roughing facing cycle that cuts towards the centerline of the part.
The 'W' on the first line is the depth of cut in Z-axis. The' R' refers to the distance that the tool pulls off of the material when moving rapidly in to the next starting point.
The 'P' and 'Q' values ​​define the start and end point of our subroutine respectively. These values ​​can be any value as long as it matches the 'N' numbers of the subroutine. This will look like the code below.
N200;
SUBROUTINE OF PROFILE;
N300;
In the above example, 'P' would be P200 and 'Q' would be Q300 so they match the 'N' numbers.
The 'U' on the second G71 line defines the amount of material we wish to leave on for a finish cut in X.
The 'W' on the second line is the amount of material we wish to leave on for a finish cut in Z.
And 'F' is our feed rate.
Rough turning with the radial toolpath roughing cycle on mastercam software for those of you who want to learn.
If the clip is useful, please like, share, and subscribe to the channel to motivate me to make the next videos!