CNC Lathe G75 Groove Cycle Tutorial with Program Example
G75 is an excellent CNC group cycle, one of the best advantages of which is that this command does not require repeated code writing, but rather contains complete logic in a single command. This code is a great way to save time, protect the tool, and achieve better quality.
G75 is typically used for radial grooving or packing grooving, in which the cutting tool cuts the material in small steps rather than going full depth at once.
This cycle is especially useful when a wide groove needs to be made on a shaft, pipe, or workpiece. The G75 command is used for step cutting rather than cutting to a greater depth in one go, which reduces stress on the tool and produces a better finish.
G75 Command Syntax
G75 R(1);
G75 X Z P Q R(2) F;| R(1) | Return amount: The distance the tool retracts after each peck to break the chip. |
| X | Final Diameter: The absolute (X) or incremental (U) finish depth of the groove. |
| Z | Final Z-axis position: The end point of the groove width. |
| P | X-axis Peck Increment: Depth of each cut in microns (no decimal point). |
| Q | Z-axis Shift: The horizontal shift amount between grooves (if cutting a wide groove). |
| R(2) | Relief at bottom: Tool retraction at the end of the cut to avoid rubbing. |
| F | Feed rate: Cutting speed in mm/rev or inch/rev. |
Rapid Move: The starting position of the tool. This position is written in the program before the G75 block starts.
The Peck: The tool is not overloaded. The tool plunges into the material a certain distance. This depth or distance is determined by the value of P. This process is called “pecking”.
The Retract: After each cut (Peck), the tool retracts a little. This distance is determined by the value of R in the first line. The purpose is to break up the “chips” (thin pieces of metal) so that they do not get stuck in the tool.
The Final Depth: When the tool reaches its final depth (X coordinate), it either dwells there for a while or returns directly to its starting position.
The Shift: You can create a wide groove using the Z and Q values. After completing one cut, the tool moves forward by the amount of Q and repeats the process until the desired width is achieved.
Simple G75 Simple Groove Cycle Example
Below is a basic G75 Groove Cycle example (Fanuc-type CNC lathe) with step-by-step explanation.
G97 S800 M03
G00 X30.0 Z2.0
G75 R1.0
G75 X20.0 Z-10.0 P200 Q300 F0.15
G00 X100 Z100
M30
