Elimination of halo gloss transition surface defects on injection-molded parts

This paper presents a novel method to eliminate halo gloss transition surface defects commonly found on large-scale injection-molded parts. Due to the increasing importance of product appearance and its influence on consumer decisions, the halo defects that deteriorate surface appearance and quality should be eliminated. The effect of the main injection molding process parameters on the halo defects was compared and investigated by correlating the injection molding simulations and defect specimens. It was found that a drastic increase in flow front speed (FFS) is the main cause of the halo defects. A multi-step injection speed approach that minimizes a drastic increase of FFS due to the reduction of flow front area according to the filling patterns is proposed. The proposed approach was experimentally validated for a simple test part and a real-world, commercial home appliance part, respectively. This approach can contribute to reducing the time for setting defect-free injection molding conditions before mass production.