Sink Marks
Sink marks are also know as shrink marks; Refers to areas of the molded part where it seems to be sunk in.
Sink marks in molded parts
Below are examples of sink marks in actual molded samples.
Why sink marks happens?
The issue of sink marks mostly are caused by non-uniform wall thickness. It is a part design problem. Adding ribs and coring out of the thick area are 2 most effective ways to solve this problem.
Sink marks in DFM Report
At Plastopia, we will analyze the wall thickness in our DFM report. It will show you the potential sink marks, and you will need to modify the parts to eliminate or reduce them.
TIP: For small size of plastic parts, the sink marks could be eliminated by adjusting injection condictions.