Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 523)

Dresser/Wheel Radius Compensation
Chapter 15
15-35
Figure 15.25 and Figure 15.26 assume that the number of blocks not
containing axes motion in the currently selected plane, following G40
before the exit move takes place, does not exceed an amount selected in
AMP by your system installer. If the number of non-motion blocks
following G40 exceeds the limit, the control generates its own exit move.
This can often cause overcutting of the part because this move is a linear
path directly back to the programmed dresser/wheel path.
I and K Vector in an Exit Move
By including an I and/or K word in the exit move, you can modify the path
that the dresser/wheel takes for an exit move. Only the I or K words that
represent values in the current plane are programmed in the block
containing the exit move. I and K are integrand words corresponding to
the X and Z axes respectively.
The I and K words in the exit move block define a vector that the control
uses to redefine the end-point of the previously compensated move. You
always program I and K words as incremental values regardless of the
current mode (G90 or G91).
Use I and K to define an endpoint of an imaginary block in dresser/wheel
radius compensation. By programming an I, K, the control assumes that
this is the end-point of an imaginary linear block. The control applies
compensation to this imaginary block to modify the end-point of the last
compensated block programmed. I and K allow you to compensate for
future moves or protect areas that should not be machined.
Figure 15.27
Exit Move Defined By An I, K Vector
Compensated path
using I, K vector
Compensated path if
no I, K in G40 block
I, K
r
Compensated path
Programmed path
Compensated path
Programmed path
r
Exit move Exit move
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