Rockwell Automation 1771-QDC, D17716.5.86(Passport) PLASTIC MOLDING MODULE - Manual (Page 13)

Chapter
1
1-1
Overview of Inject and Clamp Mode
This chapter presents an overview of the 1771-QDC Plastic Molding
Module in the inject and clamp mode. We present a summary of inject and
clamp features followed by sample applications.
Important: This manual assumes you have already read your Plastic
Molding Module Application Guide (publication 1771-4.10) and have
chosen inject and clamp as your QDC module’s mode of operation.
When you select inject and clamp mode, you can use the following phases:
Table 1.A
Glossary of Inject and Clamp Mode
Inject Phase: Description:
Injection The ram (screw) injects plastic into the mold. You can vary the velocity of the ram (screw), or the pressure
driving it, to fill areas of the mold cavity at different rates to achieve uniform quality of the molded part. This
phase can be critical to part quality. The pattern of velocity or pressure variation during injection is called the
injection profile.
Transition Detects when injection is complete.
Pack (optional) Packing pressurizes the plastic to a specified density which determines the flexibility of the molded part. To
achieve uniform density, you can release or increase pressure in steps according to cooling gradients across
the mold. Thus, as the plastic cools unevenly, the pack profile can compress the plastic uniformly.
Hold Holding lets the plastic cool and shrink slightly from the mold cavity in preparation for ejection. The effect is
similar to packing. You can hold at predetermined pressures for predetermined lengths of time throughout
the hold phase.
PreĆdecompression (optional) This single, backward movement of the ram (screw) separates plastic solidifying in the mold from molten
cushion remaining in the barrel prior to plastication. This phase is also called sprue break or suckback.
Plastication Phase The machine reloads by drawing plastic beads into the barrel containing the ram (screw). The mechanical
action of the rotating ram (screw) grinds and melts the beads. The longer it grinds, the hotter it melts. You
can vary the backpressure on the ram (screw) causing it to remain longer in an area. Thus, you can induce
any desired temperature gradient along the length of the shot by controlling ram (screw) backpressure.
PostĆdecompression
(optional)
This single, backward movement of the ram (screw) guards against drooling molten plastic into the open
mold during ejection prior to clamp close. This phase is also called melt pullback or suckback.
Chapter Objectives
Inject and Clamp Mode
Operation