Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 629)

Turning Operations
Chapter 18
18-13
Axis feedrates - When threading, the speed of the grinding axis is
determined by the spindle speed and the thread lead through the
following equation:
axis feedrate = (S) / (F threads per inch)
= (S) / (E threads per inch)
= (S)(E inches per thread)
Where : Is :
S the actual speed of the spindle (programmed spindle speed times the spindle
speed override switch setting in percent).
F threads per inch or millimeter depending on the current active mode
E threads per inch or inches per revolution as determined in AMP by your
system installer.
The programmer should use this equation to verify that the feedrate
resulting from the thread parameters does not exceed the maximum
allowable feedrate for the grinding axis. Otherwise an error results and
axis motion is stopped. This equation can also be applied to face
threads and tapered threads.
Pullout angles - During threading passes, the control synchronizes the
moves and speeds of the X, Z, and spindle axes. This occasionally
forces the X-axis to move quite rapidly in order to produce the desired
thread taper or pullout angles at the rates dictated by the active spindle
speed. Compounded with the fact that many machines have X-axis
feedrate limits lower than those for the Z-axis, velocity limitations can
result. This is best prevented by first executing a Feed Check prior to
actually grinding the threads and then reducing spindle speed or
changing the pullout angle where necessary.
Tapered Thread Lead - When grinding a tapered thread, the thread
lead (E or F word) is applied to the axis that travels the greatest distance
from the start to the end of the threading pass.
Infeed - Plunge infeed relies on a grinding wheel dressed at the exact
thread angle so that two sides of the grinding wheel are grinding as it is
fed perpendicular to the work on successive passes. On larger threads,
this type of infeed can cause vibration. In that case, angular infeed can
be preferred. This results in the grinding wheel being fed along the
thread flank with each successive pass, meaning only one side of the
grinding wheel grinds. Figure 18.11 illustrates plunge and angular
infeed.