If you find thin layers on the surface of a molded part are easily separating or peeling off the underlying material, you’re seeing a molding defect called delamination. Delamination for Injection plastic mold is a defect characterized by a flaking surface layer, similar to what you’d commonly find on flake mica. This is generally regarded as a relatively serious defect because it reduces the strength of the component.

Causes and prevention of delamination in injection molding
The most common cause of delamination is contamination of the resin pellets or other base material with a foreign material. Flaky separation results when the two materials cannot properly bond to each other. For example, you might combine a common base plastic like acrylonitrile butadiene styrene (ABS) with an incompatible plastic, such as polypropylene (PP). The resulting loss of strength of the material would be very dangerous if your part is intended for a safety-critical use.injection molding defects

Aside from material fed into the hopper, the contaminant could also be any excess release agents coating the mold for easier component separation. Excess moisture on the material, due to improper drying prior to use, can also cause delamination. Consider the following corrective actions to prevent recurrence if you discover delamination affecting your molded parts:

Increase the mold temperature or pre-dry the material properly if excess moisture is an issue
Ensure workers are properly storing and handling the resin pellets or base material to prevent contamination
Consider redesigning the mold with a focus on the injection nozzle to limit your dependence on release agents

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