Pack Settings PropertyManager

The goal of packing is to produce a part with uniform weight and dimensional integrity. A successful packing improves the part quality.

During the first stage of packing, pressure is applied to the injection system as the molten plastic in the mold cools and shrinks. The pressure forces additional material into the mold to compensate for thermal shrinkage. During the last stage of packing, 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 first stage of packing 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 to determine the new duration of the second stage of packing. Polymer flow rate is monitored at the interface between the runner and cavity domains, or at the injection locations if no runner domain has been defined. The criteria for nearly zero flow rate is satisfied when the rate of change of part mass falls below 0.01% per second.

Auto

Calculates the injection mold process parameters based on the part geometry (averaged thickness) and the material properties. Clear Auto to edit the values of the process parameters.
  Pure Cooling Time

Duration of the last stage of packing, during which 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 is still in 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.
Profile Sets the packing pressure profile. Enter the injection pressure values at different time steps.

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 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.

  Reset All Restores the default values.
Pressure distribution after filling Pressure distribution after packing