How to prevent Sink Marks defects in advance
Sink marks defects are localized depressions in the surface of injection molded parts caused by a non uniform shrinking of the plastic during the cooling process. In cosmetically critical parts, they can be a serious problem. Sink marks are dependent on part geometry and material shrink rates. Sink marks often come as a surprise when the mold is complete.
If the sink marks defects are objectionable to the customer, the mold manufacturer is often tasked with “eliminating them”. Since the mold is complete, the mold manufacturer does not have the luxury of changing the part geometry. At that point, changing the material to one with a lower shrink […]