The Sink marks, depth result indicates the location and depth of sink marks (and voids) likely to be caused by features on the opposite face of the surface.
Sink marks can occur in moldings with thicker sections, or at locations opposite ribs, bosses or internal fillets. The Sink marks, depth result only indicates sink marks likely to be caused by features on the opposite face of the surface.
The Sink marks, depth result plot is generated by a Pack analysis using Midplane analysis technology.
Sink marks appear as depressions on the surface of a molded part. These depressions are typically very small; however they are often quite visible, because they reflect light in different directions to the part. The visibility of sink marks is a function of the color of the part as well as its surface texture so depth is only one criterion. Although sink marks do not affect part strength or function, they are perceived to be severe quality defects.
Sink marks are caused mainly by thermal contraction (shrinkage) during cooling. For example, areas where a rib meets the top surface will cool slower than other regions due to restricted local contact with the colder mold surface. This in turn will cause higher shrinkage which effectively pulls the cooling plastic away from the mold surface to create depressions on the surface of a molded part.