G95 (Feed Per Revolution) modal G-code is the code which commands the CNC machine control to set the feed commands to IPR (Inches Per Revolution) or MMPR (MM Per Revolution) of the spindle.
G01 F0.02. [CNC program code]
The preceding coding will result in the advancement of the axis to 0.02 mm per revolution of the CNC spindle.
While the G95 code is running active, then the values of the feed will be coded as: F0.05, F0.15, F0.3, F0.5 and so on.
N12 G95 ; Program with G95 (F= mm/rev.)
N13 G1 Z-20 F0.2
What is a g95?
G95 (Feed Per Revolution) is a modal G-code which when remains active, the revolution of the spindle will result in a travel distance set out by the feed value. If Setting 9 is fixed to inch, then F (feed value) will be considered as inches per revolution. If the Setting is set to mm, then the value of F will be accordingly considered as mm per revolution.
When the G95 code is running active, then both Spindle and Feed Override will influence the CNC machine behavior. If the Spindle Override is chosen, then any change in the speed of the spindle will cause an adjacent change in the feed override in order to maintain an uniform chip load. Conversely, by selecting a Feed Override, any change in the value of Feed Override will influence the feed rate but not the spindle.
In order to put the active feed rate mode to UPR mode ( Units Per Minute), code G95 should be utilized.
An F word is used to indicate the controlled point must move with length per revolution of the spindle for a particular number of times, based on the type of length unit being used. G95 isn’t applicable for threading. You should use either G33 or G76 for threading.
There is an error if:
- the feed rate (inverse time) mode is active, plus, a line with G01, G02, or G03 (implicitly or explicitly) doesn’t have the F word.
- no new feed rate is specified when switched to G95 canned cycle return level – G99.
Example and Explanation of G95 Code in Simple CNC Lathe Program
Demo CNC Program:
N2 G97 S500 M03
N3 G42 G00 X0 Z0
N4 G01 X25 G95 F0.3
N5 G01 Z-7.5
N6 G01 X40 Z-15
N7 G01 Z-25
N8 G01 X60 Z-35
N9 G40 G00 X200 Z100
N1: Tool number 1 with offset number 1 FANUC Control
N2: Clockwise spindle rotation with 500 Revolution Per Minute
N3: P0 tool nose radius active compensation
N5 to N8: P1 to P4
N9: Tool nose radius compensation cancel
The above example will do for the beginners to understand the working by which G95 instructs the CNC control to interpret the feed rate as per the units mentioned earlier in this article.