Rockwell Automation 1771-QDC, D17716.5.86(Passport) PLASTIC MOLDING MODULE - Manual (Page 20)

Overview of Inject and Clamp Mode
Chapter 1
1-8
Hold Phase
The QDC module controls the hold phase with a pressure vs. time profile.
You create the profile based on controlling the hydraulic pressure against
the ram (screw). The pressure can be controlled using up to five segments.
You determine the pressure setpoints and time durations for the hold
profile based on molding requirements.
After completing the last segment of the hold phase, the QDC module
either immediately starts the optional pre-decompression movement, skips
the pre-decompression movement if none is required and immediately
starts the plastication phase, or waits for a command from your PLC-5
program to continue.
PreĆdecompression Movement
You select a length of pullback for the ram (screw) prior to the plastication
phase to separate plastic solidifying in the sprue from molten cushion
remaining in the barrel.
After completing the pre-decompression movement, the QDC module
either immediately starts the plastication phase or waits for a command
from your PLC-5 program to continue.
Plastication Phase
The plastication phase lets you achieve a melt temperature gradient in the
barrel containing the ram (screw). To program the desired temperatures,
you consult backup rate (backpressure) vs. temperature tables. You can
create the profile with up to 11 segments of position or time (figure 1.8).
You chose from two plastication profiles:
Backpressure vs. position
Backpressure vs. time