Strategic cost and sustainability analyses of injection molding and material extrusion additive manufacturing

Abstract

Economic and environmental costs are assessed for four different plastics manufacturing processes, including cold and hot runner molding as well as stock and upgraded material extrusion three dimensional (3D) printers. A larger stock 3D printer was found to provide a melting capacity of 14.4 ml/h, while a smaller printer with an upgraded extruder had a melting capacity of 36 ml/h. 3D printing at these maximum melting capacities resulted in specific energy consumption (SEC) of 16.5 and 5.28 kWh/kg, respectively, with the latter value being less than 50% of the lowest values reported in the literature. Even so, analysis of these respective processes found them to be only 2.9% and 3.8% efficient relative to their theoretical minimum energy requirements. By comparison, cold and hot runner molding with an all‐electric machine had SEC of 1.28 and 0.929 kWh/kg, respectively, with efficiencies of 9.9% and 13.6% relative to the theoretical minima. Breakeven analysis considering the cost and carbon footprint of mold tooling found injection molding was preferable at a production quantity of around 70,000 units. Parametric analysis of model inputs indicates that the breakeven quantities are robust with respect to carbon tax incentives but highly dependent on mold costs, labor costs, and part size. Dimensional and mechanical properties of the molded and 3D printed specimens are also characterized and discussed.

Novel advancements in additive manufacturing of PLA: A review

“…Meanwhile, PNCs have been fabricated with enhanced thermal and electrical conductivity, improved mechanical and thermal expansion, and increased fire retardancy for automotive, oil and gas, and other versatile applications 137–207 . Finally, it is emphasized that 3‐DPT and 4‐DPT are innovative processing technologies, presenting the future route of the manufacturing sector 208–244 …”

Steady melting in material extrusion additive manufacturing

“…That being said, the custom hot end design shows better performance than a typical hot end design (see supplementary materials Section S.11). Hot end performance is critical because it affects the systems energy efficiency (Kazmer et al , 2023) and the material properties (Kazmer et al , 2021; Kim et al , 2021), which affect the final part’s properties.…”

Mechanical and crystallization properties of hot runner injection molded virgin and recycled polypropylene

“…23 However, as reported by Kazmer et al, hot runner molds are a preferred choice over cold runner molds for complex parts having significant production quantities. 24 To mitigate the issues with processing recycled feedstocks, blending (i.e., up to 40% wt.) with virgin material is the most common strategy to maintain the required mechanical properties.…”

“…Additional molding defects, including asymmetrical filling, flow marks, voids, and discoloration, can develop with a poorly optimized system 23 . However, as reported by Kazmer et al, hot runner molds are a preferred choice over cold runner molds for complex parts having significant production quantities 24 …”