Surface strengthening of injection molded parts by applying a thermal insulation film

The main objective of this study is to strengthen the surface of injection molded parts by building up the compressive residual stress at the surface of the product. For this, we introduced a mold system for manipulating the heat transfer between the mold and the molten polymer with use of a thermal insulation film. The injection molding process was simulated, and the residual stress was obtained numerically. Experimental analysis of residual stress was also carried out using the hole drilling method. In addition, the scratch resistance and mechanical characteristics of the products were evaluated. The results indicated that the compressive residual stress was built up by employing the film and led to significant enhancement of the scratch resistance and mechanical properties of the molded parts.