Specifications

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CONCISE GUIDE FANUC 32
3.8 “G97” FIXED REVOLUTIONS SPINDLE ROTATION
Function G97 prepares the spindle speed in revs/min (fixed revs) set by the code S. When this function is
active the programmed S value represents the actual number of revolutions per minute of the spindle.
(e.g.: S50, S160, S500, S1200, S3200, S5000 etc.). G97 is automatically activated when the control is
switched on, therefore it is not necessary to specify its activation in the program. It is a modal function
and can be cancelled by programming G96 (cutting speed set Vt [m/min.]).
This function is recommended when drilling and thread cutting, and is necessary for tapping.
Programming an S value with G97 active, and knowing the working diameter, the cutting speed value can
be calculated using this formula:
To calculate the cutting speed for machining performed at 1500 rpm on a diameter of 40:
Vt = ? [m/min.]
π = 3.14
D = 40 mm
n = 1500 rpm.
A block containing G97 is programmed:
N4 T101
N5 G97 S1500 M4
N6 G0 X100 Z3 M8
Where:
• G97 => Spindle speed set in rpm
• S1500 => Number of spindle rpm
• M4 => Spindle direction of rotation
Vt =
π x D x n
1000
Where
Vt => cutting speed [m/min]
π => 3.14
D => work diameter
n => rpm
1000 => m to mm conversion
Vt =
3.14 x 40 x 1500
1000
= 188.4