In a recent webinar, I received this short question…
Does the use of in-mold labelling have a significant effect on polymer flow?
Basically, there should be no significant change in the behaivor of the polymer. Since the polymer exhibits fountain flow, the polymer touching the label surface is stagnant, while the moving polymer passes through the center.
Many injection molders forget that the polymer does not flow through the mold with a straight plug flow as water does. In fountain flow, the polymer comes in contact with the mold surface and begins to freeze off.
The polymer behind the flow front passes through the center of the channel until it comes in contact with the mold surface. As a result, All the polymer that fills the mold comes from the center of the flow channel as is passes by the polymer it distributes onto the mold surface.