The average volumetric shrinkage result shows the average value of volumetric shrinkage over the half-gap thickness for 3D models.
As the mass of an element changes (for example, with polymer flow during packing), shrinkage continues to change with each change in the element's pvT state. Once the mass stops changing, the element's current pvT state is fixed in the shrinkage calculation as the reference state.
The mass of an element stops changing when the cavity pressure has decayed to zero. After this, the volumetric shrinkage becomes a constant. However, if the holding pressure is removed before the material is frozen or while the pressure in the cavity is still non-zero, the volumetric shrinkage may rebound due to possible backflow into the nozzle or other warmer areas of the part.
The average volumetric shrinkage for 3D is the average value of volumetric shrinkage over the half-gap thickness, and is plotted on the surface. This result can be used to detect sink marks on your model. High shrinkage values could indicate sink marks or voids inside the part.
Volumetric shrinkage should be uniform across the whole part to reduce warpage.
Volumetric shrinkage can be controlled by the use of packing profiles.
For molded materials, the linear shrinkages in the thickness, flow and transverse directions depend on the effects of relaxation and orientation.