Part inserts are components that are placed into the mold before the injection phase, and are ejected with the part.
A part insert can be modeled with a Midplane mesh if the part insert is not required to be a solid model. The part insert is modeled separately from the plastic part when using a 3D mesh or Dual Domain mesh.
Examples of part inserts include In-mold labels, which are very thin part inserts (less than 1mm thick). Labels are applied to the mold before each injection. As the label has different material properties, which greatly affect the flow and cooling behaviour, they need to be modeled separately.