Rockwell Automation 1771-QDC, D17716.5.93(Passport) PLASTIC MOLDING MODULE - Manual (Page 245)

Tune Your Machine
Chapter 10
10-17
After the QDC module sets them, they remain set until the QDC module
is commanded to start another movement or profile, or until the stop
command is asserted
PreĆ and PostĆdecompression Pullback
(for preĆdecompression PRC05)
(for postĆdecompression PSC05)
Pre-decompression separates plastic solidifying in the sprue from the
molten cushion remaining in the barrel. The QDC module applies pre-
decompression pullback to the ram (screw) after hold, before plastication.
Post-decompression guards against drooling molten plastic into the open
mold when the clamp is opening. The QDC module applies post-
decompression pullback to the ram (screw) after plastication.
When configuring pre- and post-decompression:
Enter values into PRC05 and PSC05 only after you have tested shot size
and cushion (PPC61 and PPC62).
Enter set-output values into PRC09-12 and PSC09-12 for the pre-and
post-decompression movements equal to the ram (screw) reverse jog
set-output values (JGC25-28) from chapter 5.
Enter end-of-movement set-output values into PRC33-36 and PSC33-36
as required by your application.
Acceleration and Deceleration Ramp Rates
The zero ramp rate values entered in chapter 7 disabled ramping. This
forces the QDC module to step from setpoint to setpoint during a profile.
If required by your application, you may configure your QDC module to
ramp its outputs during a profile. The QDC module uses configured
acceleration and deceleration ramp rates to move all outputs from setpoint
to setpoint during execution of any profile (figure 10.1).
ATTENTION: Ramp rates are not applied until the QDC
module is actually executing the profile. Because ramp rates
are time based, using excessively slow (low value) ramp rates
may inhibit effective closed-loop control, reduce ERC
calculation accuracy, and limit QDC control capability. Use
ramps only if machine operation mandates them.