Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 434)

Axis Motion
Chapter 12
12-62
Your system installer can install an optional external deceleration switch if
desired. Typically this is a mechanical switch mounted on the machine
axes inside the hardware overtravel switches (refer to documentation
prepared by your system installer for details on the application and location
of this switch).
When this feature is active, any axis moves that are to take place at a
grinding feedrate (G01, G02, G03, etc.) use a special feedrate assigned in
AMP. When this feature is active, any axis moves that are to take place at
a rapid feedrate (G00, etc.) also uses a special feedrate assigned in AMP.
These feedrates are independent of each other and typically have different
values. These feedrate changes take place immediately when the feature
becomes active, even if this is in the middle of block execution.
Important: The feedrate set for the external deceleration feature for
grinding moves does not exceed the maximum grinding feedrate.
If you use this feature simultaneously with the dry run feature the feedrates
that are assigned to the external deceleration feature are used. The
feedrates for this feature are not related to the dry run feedrates although
the operation of this feature is similar to dry run.
This feedrate is unaffected by the <FEEDRATE OVERRIDE> switch, and
the <RAPID FEEDRATE OVERRIDE> switch settings and operates as if
the switches are set at 100%. Blocks that are programmed to move at the
rapid feedrate are still executed in the rapid mode.
Typically this feature protects the machine from harsh or sudden stops. If a
very high feedrate is active at the time that a hardware overtravel occurs,
damage to the machine can result if a sudden stop is performed at the
overtravel or the machine can coast past a safe range for axis motion. If
the switch is installed before the overtravel area, the feedrate of the move
is reduced and the amount of coast into the overtravel area is much less.
If the current feedrate is less than the feedrate set for the external
deceleration feature, it is accelerated to the external deceleration feedrate.
This can cause problems with part finish or can damage the wheel.
ATTENTION: Your system installer can write PAL to allow
the operator to select the external deceleration feedrate at any
time. This means that during normal automatic operation, the
operator can select external deceleration and replace all
feedrates in the program with the external deceleration
feedrates. This can result in damage to the machine, part, or
injury to the operator.
12.8.2
External Deceleration
Feedrate Switch