Average volumetric shrinkage result

Using this result

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.

Things to look for

• Localized areas of high shrinkage can result in internal voids or sink marks when the part cools.
• Shrinkage values should be uniform throughout the part. This is important for good packing of the material, ensuring good structural and visual integrity of the part. Use a packing profile to make the shrinkage more uniform.
• Negative volumetric values indicate expansion rather than shrinkage. Avoid negative shrinkage on ribs as this can cause ejection problems.
• Are the values in the expected range for the material?
  • Materials that shrink isotropically have a linear shrinkage which is approximately one third of the volumetric shrinkage.

    For molded materials, the linear shrinkages in the thickness, flow and transverse directions depend on the effects of relaxation and orientation.

  • For shell-like geometries, it is expected that the shrinkage in the thickness direction should be higher than the shrinkage in the plane of the part. Shrinkage in the thickness direction is likely to be greater than one third of the volumetric shrinkage, while in-plane shrinkage should be less than one third of the volumetric shrinkage. Many mold features act as constraints to in-plane shrinkage. If you are using a fiber-filled material, the orientation of the fibers in the plane of the part will limit shrinkage in this direction. Shrinkage in the thickness direction is relatively unconstrained.