Delamination


What is delamination?

Delamination (sometimes called lamination or layering) is a defect in which the surface of a molded part can be peeled off layer by layer.

FIGURE 1. Delamination causes layer-wise peel-off on the surface of a molded part

Causes of delamination
Delamination can be caused by several factors, including:

Remedies


Change the material preparation


Avoid using foreign material or contaminated regrind material in the molding process.


Alter the mold design


Smooth all of the corners at the gate and runner.
Sharp corners can tear apart melt flow and cause lamination.


Adjust the molding conditions


Avoid using excessive mold release agent to fix the de-molding problem.
Delamination can be caused by excessive use of mold release agent. You should repair the ejection system or other problems to eliminate the difficulty of de-molding instead of over-using the mold release agent.


Follow the pre-dry instructions for the specific material and pre-dry the material properly before molding.
Excessive moisture heats up and forms steam, which results in lamination on the surface.


Increase the barrel temperature and mold temperature.
If the melt temperature is too low, layers of material are formed because they can't bond to each other. When ejected or subjected to stress, they separate from each other.