3D-printed injection mold inserts for sustainability and circular economy

Abstract Plastic injection molding traditionally relies on Mold Inserts (MIs) produced through subtractive manufacturing, which generates significant waste. This study investigates the environmental impact, performance, and cost of 3D-printed MIs as a sustainable alternative for low-volume production. Four MI configurations were developed using High Temp and Rigid 10k resins, namely, MI-A and MI-B (High Temp resin in solid and hollow designs) and MI-C and MI-D (Rigid 10k resin in solid and hollow designs) via Vat Photopolymerization (VPP). Among them, MI-C (Rigid 10k, solid) demonstrated the highest durability, enduring 250 shots during injection molding, while MI-A and MI-B fractured after four and five shots, respectively. Cost analysis revealed that 3D printing offers substantial savings for small production runs, reducing fabrication costs by 43.19% for batches of 250 units or fewer. The carbon footprint of 3D-printed MIs ranged from 27.466 to 28.579 kg CO 2 eq. per MI, with propylene production and consumption—integral to resin fabrication and post-processing—accounting for 15.7% to 16.3% of total emissions. These findings highlight 3D-printed MIs as a promising, cost-effective, and environmentally conscious alternative to traditional methods.