Effect of Injection Molding Parameters and Cooling Conditions on the Dimensional Stability and Mechanical Properties of Polypropylene Battery Boxes for Automotive Batteries

This study investigates the influence of injection molding parameters, including tem-perature, cooling duration, and coolant flow conditions, on the dimensional stabilityand mechanical properties of automotive battery boxes made from polypropylene im-pact copolymer (PPIC). PPICs are widely used materials for battery boxes becauseof their strength, toughness, chemical resistance, and low cost. Interruption of theflow of coolant to the mold was shown to cause warpage in specific regions. Lowerinjection temperatures (220 °C) showed greater robustness to coolant anomalies,maintaining dimensional stability despite cooling disruptions. Mechanical testing of tensile bars extracted from the molded boxes revealed sig-nificant orientation-dependent behavior, with longitudinal samples exhibiting supe-rior elongation and toughness compared to transverse samples. Notched tensile barsconfirmed strain rate sensitivity, highlighting the brittleness of PPIC under highdeformation rates. A machine learning model was used to optimize elongation as afunction of processing parameters, revealing optimal ranges for injection temperature(220–234 °C) and cooling time (38-47 s). These findings provide actionable insights for optimizing the injection moldingprocess to minimize defects, enhance mechanical performance, and improve reliabilityin PPIC battery boxes. Future work should focus on exploring additional parame-ters, including resin composition and mold design, to further refine manufacturingoutcomes.