Investigating metal injection molding of 4605 low-alloy steel powder-polymer mixture: parametric optimization of the injection stage using RSM technique

Abstract

This work refines the metal injection molding (MIM) process for creating a bend-type thin-walled engine component from 4605 low-alloy steel. Utilizing a five-factor Box–Behnken design (BBD) and response surface methodology (RSM), we optimized the injection parameters. Differential scanning calorimetry (DSC) and rheology analysis helped establish the parameter ranges. The optimal injection conditions were determined to be as temperature of 155 °C, speed of 80 mm/s, holding pressure of 83 bar, holding time of 9 s, and injection pressure of 132 bar, resulting in an ideal green part density of 4.892 g/cm³. The injection pressure was found to be the most critical factor affecting the density of the prepared green part. A sample produced under these conditions closely matched the expected density, and after sintering, its density and hardness conformed to the MIM-4605 standards, demonstrating the effectiveness of the optimized parameters. This research work not only pinpointed the optimal conditions for the MIM process but also highlighted the significant role of injection parameters in determining quality of the parts. These findings provided valuable insights for the manufacturing industry, especially in the precision fabrication of engine components. Future research directions include expanding the study to different materials and geometries, evaluating long-term mechanical properties, incorporating machine learning for enhanced optimization, and assessing the environmental impact of the MIM process.

Graphical abstract