Plastic injection molding manufacturing method is considered both science and art. The injection molding process can be described as heating plastic pallets to molten state, injecting molten plastic tin the cavities then cooling the plastic to solidify the plastic. The injection molding process does have some drawback in the form of defects. The defects can be observed on the components. The defects in plastic injection molding can be attributed to material selection, part design, tool/mold design and process settings or any combination of material, part, tool and process. The defects can be first observed during the tool/mold verification/validation trials. The defects can also be observed during production. The defects can be resolved by modifications to part, tool, process settings or any combination of material, part, tool and process. Resolving defects by changes in process settings is very cost effective.
Process settings in the plastic injection molding process involves very good understanding of material properties, tool design and capabilities of injection molding machine/press. Most of the defects are caused due to thermal imbalances in the molten material flow path. This article discusses causes and possible solutions to some of the plastic injection molding defects that can be observed on a part.