TABLE OF CONTENTS Feedrate is the closest programming companion to spindle function. While the spindle function controls spindle speed and spindle rotation direction, feedrate controls how fast the tool will move, usually to remove excessive material (stock). In this handbook, subject of rapid positioning, sometimes called a rapid motion or rapid traverse motion, is not considered a true feedrate and will be described separately, starting on page 147.
Cutting feedrate is the speed at which the cutting tool removes the material by cutting action
A cutting action may be a rotary tool motion (drilling and milling, for example), rotary motion of the part (lathe operations), or other action (flame cutting, laser cutting, water jet, electric discharge etc.). Feedrate function is used in CNC program to select correct feedrate amount, suitable for the desired action.
Two feedrate types are used in CNC programming:
Feedrate per minute - mm/min or in/min
Feedrate per revolution - mm/rev or in/rev
The most common types of CNC machines, machining centers and lathes, can be programmed in either feedrate mode. In practice, it is much more common to use the feedrate per minute on machining centers and the feedrate per revolution on lathes.
There is a significant difference in G-codes used for machining centers and lathes.
| FEEDRATE | Milling | Turning Group A | Turning Group B | Turning Group C |
|---|---|---|---|---|
| Per minute | G94 | G98 | G94 | G94 |
| Per revolution | G95 | G99 | G95 | G95 |
G-code Group A is the most commonly used on...
