Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 554)

Surface Grinding Fixed Cycles
Chapter 16
16-4
Reciprocation
ATTENTION: Reciprocation differs from conventional axis
motion in that the reciprocating axis has no final destination.
Once axis reciprocation begins, it continues through program
block execution until stopped by a G80 or an end of program
(M02, M30, M99). This means pressing single block or cycle
stop does not necessarily stop the reciprocating axis.
Important: The motion of the reciprocating axis and, consequently, the
grinding cycles can be significantly altered through the control’s PAL
program. See your PAL reference manual and/or the literature prepared by
your system installer.
Important: The reciprocating axis cannot be mirrored (G51.1) and cannot
be rotated (G68) before or during reciprocation.
The reciprocating axis is the axis that sweeps back and forth across the part
surface (or under the grinding wheel, depending on your machine
configuration). Programming a G81 causes reciprocation mode to become
active. The reciprocation axis is whichever axis is programmed in the G81
block. Only one axis name can be programmed in a G81 block.
For the surface grinding cycles (G82 through G86) the reciprocation axis is
always an axis that is not in the active plane. For example, if you have
G19 (YZ) active and configured as shown above, then typically the X axis
would be programmed as the reciprocating axis for the surface grinding
cycles. Any other axis not in the active plane (U, V, or W for example)
could instead be programmed as the reciprocating axis.
The reciprocating motion is divided into a primary reversal and a
secondary reversal. The reversal points of the primary and secondary
reciprocation moves are defined by the numeric values associated with the
reciprocating axis name and the reciprocating axis integrand. Reversal
points can be an incremental distance from the start point (G91 active), or
an absolute position (G90 active).
Axis motion can be commanded while reciprocation mode is active. If the
axis to be moved is independent of the reciprocation, then motion begins as
soon as the block is executed.