Sink marks estimate result
The Sink marks estimate result displays simulated sink marks on the part.
The Sink marks estimate result displays the calculated depths of sink marks in the part, and shows a legend to detail the depth differences.
This result indicates the presence and location of sink marks (and voids) likely to be caused by features on the opposite face of the surface. Sink marks typically occur in moldings with thicker sections, or at locations opposite ribs, bosses or internal fillets. The result may also indicate sink marks caused by locally thick regions which are not ribs.
Notes:
You can modify the properties of the Sink marks estimate result in order to visualize a shaded result.
This result is not available for the gas-assisted injection molding process or processes for thermoset molding materials.
For 3D models, the sink mark depth may be positive or negative. A positive value occurs for a regular sink mark. A negative depth can occur at the opposite side of a negative rib (where the part thickness is less than that of the adjacent region). A negative sink mark depth will be seen as a bump (instead of a sink) in the molded part.
Using this result
As sink marks are a visual rather than a structural defect, the result should be evaluated against the part's visual design specifications. Lighter colors and textured surfaces tend to make sink marks less visible.
The result index indicates a degree of severity of depth as affected by the material, part geometry, position relative to the injection location and mold filling conditions. Changing any of these would allow you to determine its contribution to the sink marks severity.
Generally, if the thickness of the rib is less than or equal to 60% of the main wall section then, there are likely to be no significant sink marks.
If it is not possible to remove or reduce a sink mark, you can conceal it. This can be done by adding a design feature, such as a series of serrations on the area where it occurs.
Things to look for
To reduce the occurrence of sink marks try one of these options:
- Alter part design to avoid thick sections and reduce the thickness of any features that intersect with the main surface.
- Relocate the gate to or near the problem areas. This allows these sections to be packed before the thinner sections between the gate and the problem areas freeze.
- Increase the size of gates and runners to delay the gate freeze-off time. This will allow more material to be packed into the cavity.
- Sometimes, decreasing the melt and mold temperature may be sufficient. Alternatively, a less viscous melt can be used.