Pack Settings PropertyManager

The goal of the packing stage is to add more polymer material to the filled cavity to compensate for part shrinkage, and reduce external sink marks.

During the packing stage, pressure is applied to the cavity through the injection locations as the melt in the mold cools and shrinks. The pressure forces additional material into the mold to compensate for thermal shrinkage. During the "pure cooling” stage, the injection pressure is removed, and only the temperature of the part is calculated as the freezing completes.

To open the Pack Settings PropertyManager:

  • In the PlasticsManager, expand INPUT > Process Parameters. Double-click Pack Settings.

Process Parameters

  Pressure Holding Time

Duration of the first stage of packing, during which pressure is applied to the injection locations as the melt in the mold cools and shrinks. The program calculates the default value based on part geometry and material properties.

The pressure holding time is the interval between the packing switch point and the packing end point. The control type changes to pressure control after the packing switch point, and the pressure profile of inlet is then based on the proportion of packing time and injection pressure.

The packing stage will automatically end if the polymer flow rate becomes nearly zero, and any remaining Pressure Holding Time will be added to the Pure Cooling Time. The criteria for nearly zero flow rate is satisfied when the rate of change of part mass falls below 0.01% per second.
  Pure Cooling Time Defines the time when the pressure is removed from the injection locations and only the temperature of the part is calculated as the freezing completes. The default time for the cooling stage is estimated based on the ejection temperature provided in the material data.

When the part reaches the ejection temperature, it means that the frozen layer is thick enough to eject. The part core may still be in a molten state, and it cools down out of the mold to reach the ambient temperature.
  Residual Stress Calculation

Calculates the residual stresses that develop within the part as it cools down from the melt temperature to the glass transition temperature.

Residual stresses develop due to non-uniform cooling and pressure variations that occur in the viscoelastic polymer material during molding. A part with high levels of residual stresses might fracture, or it might undergo other physical changes after molding.
Pressure Profile Setting The packing pressure profile specifies the time-varying behavior of the packing pressure to sufficiently pack out the mold cavity. You can control the variation of packing pressure in terms of packing time, either in percentage or in absolute values.

By default the overall packing time is divided into five sections. Set more or fewer sections to obtain the desired process control.

Machine pressure control (Absolute Control)

Sets the packing pressure in absolute values according to the total packing time, which is controlled by the machine, or as a percentage of the current machine maximum injection pressure (set in Fill Settings PropertyManager).

Relative to pressure at filling end (Relative Control)

Sets the packing pressure as a percentage based on the pressure at the end of the filling.

Profile Time

Sets the time values as absolute time or as a percentage of the Pressure Holding Time.

  Apply Applies the current settings to the curve of the packing pressure profile. This curve controls the packing pressure stage.
  Reset All Restores the default values.
Pressure distribution after filling Pressure distribution after packing