Injection Molding defect:molding delamination

Solving delamination problems

Definition
Delamination, sometimes referred to as lamination or layering, is a defect in which the surface of a molded part can be peeled off layer by layer.molding delamination

Causes
High shear stress
Incompatible materials blended together
Excessive use of mold release agent
Excessive material moisture
Excessive moisture heats up and forms steam, which results in delamination on the surface.
Material degradation
This can be caused by excessive injection speed, residence time or melt temperature. Improper screw or runner system design may also lead to material degradation.

Remedies
Eliminate Degradation and Excessive Shear Stress
Reduce shear stress
Remove excessive moisture
Material suppliers can provide optimum drying conditions for the specific materials.
Reduce regrind material
Avoid 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.
Avoid material contamination

Solving one problem can often introduce other problems to the injection molding process. Each option hence requires consideration of all relevant aspects of the mold design specification.