SUSTAINABILITY EVALUATION OF TRADITIONAL AND ADDITIVE MANUFACTURING FOR MOLD INSERT APPLICATION

The exceptional speed and quality achieved through injection molding have made it a great tool for high-volume production. However, the time-consuming process of debugging molds makes it expensive and leads to resource wastage. In response to the fast-growing demand for low-cost and fast production, additive manufacturing (AM) emerges as a promising candidate for cost-effective mold design and fabrication. This innovative approach not only circumvents the high initial investment of tooling associated with traditional injection molding but also offers significant advantages in terms of flexibility in design and manufacturing. Moreover, it provides the potential for creating customized molds on demand, allowing for reduced lead times and enabling rapid production. In this study, a comparative analysis is conducted to evaluate an injection mold insert produced using traditional machining processes and AM. An injection mold insert is designed for pharmaceutical applications and then manufactured using a computer numerical control (CNC) machine tool and two popular AM processes – fused deposition modeling and stereolithography. A combination of three critical AM process parameters (i.e., layer thickness, build angle, and infill rate or post-curing time) is selected and used for fabricating the injection mold inserts; meanwhile, sustainability and quality are evaluated. More specifically, the total energy consumption is quantified and compared for the three manufacturing processes, and the unit manufacturing cost is computed comprising energy cost, labor cost, and materials cost. In addition to sustainability measures, the mechanical strength in terms of hardness of the mold inserts is also investigated as their ability to withstand the high pressures encountered during the injection molding process affects the number of molding cycles before a failure. The dimensional accuracy is also experimentally analyzed to evaluate whether the injection molded products will be manufactured to appropriate tolerances. The results of this study confirmed the feasibility of adopting AM techniques as a viable alternative for injection mold insert manufacturing with lowered unit manufacturing costs and reduced energy consumption. The lower mechanical performance of additive-manufactured mold inserts compared with CNC-machined metal parts suggests a reduced number of molding cycles it can withstand, necessitating further research efforts. Addressing this challenge underscores the need for future studies to enhance the mechanical properties of additive-manufactured molds for expanded applicability of AM techniques in the field of rapid tooling used for mold production. The findings of this work present promising cost and energy-saving possibilities through the adoption of AM techniques, providing broader implications for sustainability and circular economy practices.