Optimizing the Surface Quality of Microcellular Injection Molded Components Through Advanced Film‐Assisted Decoration Technology

In the field of plastic processing, although microcellular injection molding (MIM) can effectively reduce part warpage, surface defects are still the main challenge. This study combines in‐mold decoration (IMD) with MIM technology to introduce decorative films to improve the surface quality of foamed parts. A multiphase flow/solid coupling heat transfer model considering the air layer between the film and the mold was established, revealing the heat transfer hysteresis effect of the decorative film. When the thermal conductivity of the film is low or the thickness is large, the effect is enhanced, increasing the average diameter of the pores near the film (from 45.3 to 89.5 μm), a decrease in density (from 3.78 × 10 6 to 2.96 × 10 6 cells/cm 3 ), and an increase in surface roughness (Ra value from 0.044 to 0.845 μm). Experiments show that, when a 0.1‐mm‐thick polypropylene (PP) film works in synergy with an air layer, the equivalent thermal conductivity is reduced to 0.159 W/m K, forming an ideal thermal barrier, optimizing the surface roughness Ra to 0.044 μm, and significantly improving the surface quality. The research results provide a theoretical basis for optimizing the quality of foamed parts in industrial applications, and especially provide new ideas for the selection of film materials and the regulation of process parameters in low‐cost mass production.