Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 411)

Axis Motion
Chapter 12
12-39
Figure 12.21
Part Spindle Speed Modified for CSS
Part speed (N
p
)
Part
Part diameter
(D
p
)
Wheel speed
(N
w
)
Wheel diameter
(D
w
)
Part speed is modified to
maintain constant surface
speed
12034-I
Use the following equation to determine part speed in RPM when CSS is
active. This equation is for reference only. The value obtained here is
calculated automatically by the control and there is no need to program it.
(S
program
)(K)
N
p
= (--------------)
D
p
Where : Is :
N
p
Speed of part wheel (rpm) 1
S
program
Surface speed programmed in the G96 block (m/min or feet/min) 1
K Constant 318.31 (1000/
π
) for metric system or 3.8197 (12/
π
) for inch system
D
p
Diameter at which part is being ground (mm or inch)
1 if using units of seconds, make sure all S and N values are entered in seconds
Since the wheel spindle is not controlled by the S--word, grinding wheel
surface speeds relative to a stationary wheel dresser cannot be held
constant using CSS. Instead the wheel spindle speed should be a
compromise speed (in RPM) that best accommodates the variations in
surface speed as the wheel is dressed at different diameters.