Profiles are used to ensure that the simulation matches the actual molding process as accurately as possible.
Ram speed, velocity or filling profiles are used in the filling phase to control the movement of the screw. Pressure or packing/holding profiles are used in the packing/holding phase to control the packing and holding pressure applied to the mold. The change from velocity to pressure profile control occurs when the velocity/pressure switch-over point is reached. Both types of profiles help reduce mold defects such as flashing, short shots, jetting, burning, sink marks, warpage, flaking, and more.
Changes in the filling profile are typically set to correspond with changes in the mold geometry taking into account the flow restrictions inside the mold. The aim of profiling is to maintain a constant flow front. When the flow front reaches a cross sectional constriction within the mold, the rate of injection (screw velocity) should be reduced. It should be increased when the cross sectional area at the flow front increases. This is important when the flow front reaches the gate. If the melt is injected too fast, it can result in jetting, burning, flaking, melt degradation and surface defects. A common approach is to use a high screw velocity while the melt is moving through the runner system to avoid cooling of the flow front, reduce the velocity when the flow front approaches the gate, and finally increase the velocity once the melt is filling the part.
The velocity should be reduced when the flow front reaches the end of filling to prevent overpacking of the cavity, which may cause stress problems, warpage, and flashing. This facilitates a smooth transition to the packing phase where a pressure profile is used to ensure uniform shrinkage, reduce warpage, and to pack the part well without overpacking.
Use a profile dialog to edit profile settings.
Profiling operating parameters can give greater control over the final product. Different profiles can be modeled to ensure an accurate analysis.
Linear profiles specify operating parameters, such as pressure or flow rate, which increase or decrease in a linear manner through a step.
Constant profiles specify operating parameters, such as pressure or flow rate, which have a constant value through a step.
There are two fundamentally different ram speed or filling profiles.
The efficacy of thermoplastic packing has important effects on warpage, shrinkage, and the incidence of defects, such as sink marks. The main output of a Pack analysis is volumetric shrinkage, and the distribution and magnitude of volumetric shrinkage play a key role in part quality.
Temperature profiles enable you to specify the surface temperature of a specific zone of the mold during the molding cycle.
Gas injection profiles are used in gas injection molding to control the velocity of the gas, which in turn controls the velocity of the polymer flow front.
Packing/holding profiles are used during the packing and holding phases to reduce defects in the part due to uneven shrinkage, warpage, and overpacking.
Combinations of temperature profiles can be applied to the mold surface of a part.