
B–61404E/08
9. SPINDLE SPEED FUNCTION
(S FUNCTION)
PROGRAMMING
103
G96 (constant surface speed control command) is a modal G code. After
a G96 command is specified, the program enters the constant surface
speed control mode (G96 mode) and specified S values are assumed as a
surface speed. A G96 command must specify the axis along which
constant surface speed control is applied. If address P is omitted, P0 is
assumed. A G97 command cancels the G96 mode. If an S value is
omitted in a G97 block, the last speed specified in the G96 mode remains
valid. When constant surface speed control is applied, a spindle speed
higher than the value specified in G92S_; (maximum spindle speed) is
clamped at the maximum spindle speed. When the power is turned on,
the maximum spindle speed is not yet set and the speed is not clamped.S
(surface speed) commands in the G96 mode are assumed as S = 0 (the
surface speed is 0) until M03 (rotating the spindle in the positive
direction) or M04 (rotating the spindle in the negative direction) appears
in the program.
The spindle speed (rpm) almost coin-
cides with the surface speed (m/min)
at approx. 160 mm (radius).
Radius of work
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300
(n)
3000
2800
2600
2400
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
0
Spindle speed (rpm)
50
100
200
300
400
S 600m/min
Fig. 9.3 (a) Relation between workpiece radius, spindle speed
and surface speed
Explanations
D Constant surface speed
control command (G96)