A Simple Method of Reducing Coolant Leakage for Direct Metal Printed Injection Mold with Conformal Cooling Channels Using General Process Parameters and Heat Treatment

Direct metal printing is a promising technique for manufacturing injection molds with complex conformal cooling channels from maraging steel powder, which is widely applied in automotive or aerospace industries. However, two major disadvantages of direct metal printing are the narrow process window and length of time consumed. The fabrication of high-density injection molds is frequently applied to prevent coolant leakage during the cooling stage. In this study, we propose a simple method of reducing coolant leakage for a direct-metal-printed injection mold with conformal cooling channels by combining injection mold fabrication with general process parameters, as well as solution and aging treatment (SAT). This study comprehensively investigates the microstructural evolution of the injection mold after SAT using field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. We found that the surface hardness of the injection mold was enhanced from HV 189 to HV 546 as the Ni-Mo precipitates increased from 12.8 to 18.5%. The size of the pores was reduced significantly due to iron oxide precipitates because the relative density of the injection mold increased from 99.18 to 99.72%. The total production time of the wax injection mold without coolant leakage during the cooling stage was only 62% that of the production time of the wax injection mold fabricated with high-density process parameters. A significant savings of up to 46% of the production cost of the injection mold was obtained.

Automated summary

The direct metal printing technique for manufacturing injection molds offers potential for creating complex conformal cooling channels using maraging steel powder, commonly used in automotive and aerospace industries. However, the disadvantages of narrow process window and lengthy production time are drawbacks. This study proposes a simple method to reduce coolant leakage in direct-metal-printed injection molds by combining mold fabrication with process parameters and solution and aging treatment (SAT). The study comprehensively examines the microstructural changes in the injection mold after SAT, revealing surface hardness enhancement and pore size reduction. The total production time and cost savings achieved were significant, demonstrating the effectiveness of the proposed method.