Rockwell Automation 1771-QDC, D17716.5.86(Passport) PLASTIC MOLDING MODULE - Manual (Page 21)

Overview of Inject and Clamp Mode
Chapter 1
1-9
Figure 1.8
Plastication Phase Example
1 2 3 4 5 6 7 8 9 10 11
Position or Time
Mold
End
Back
Point
hotter
cooler
Barrel Containing the Melt
Temperature Gradient
BackĆPressure
Example Benefits of Profiling a Plastication Phase
The higher the backpressure during plastication, the slower the backup rate
and higher the resultant temperature of the melt. You can achieve the
desired temperature gradient by lowering ram (screw) backpressure to
accelerate the backup rate and decrease the temperature of the melt along
the length of the barrel.
After completing the last segment of the plastication phase, the QDC
module either immediately starts the post-decompression movement or
waits for a command from your PLC-5 program to continue.
PostĆdecompression Movement
You select a length of pullback of the ram (screw) after the plastication
phase to guard against drooling molten plastic into the open mold during
ejection. The QDC module notifies your PLC-5 program when the
post-decompression movement is complete.