Researchers from the University of Navarra, IKOR Technology Centre, GAIKER Technology Centre, and Valencian International University have published a systematic review examining how additive manufacturing can be used to produce mold inserts for plastic injection molding.
Published in Rapid Prototyping Journal, the paper reviews 67 studies from 2013 to 2024 on 3D printed mold inserts made using polymer and metal additive manufacturing processes. The authors found that material jetting, vat photopolymerization, and laser powder bed fusion with metals are the most widely reported AM routes for insert production.
Additive manufacturing was found to be a feasible option for producing injection mold inserts, particularly for prototypes, temporary tooling, short production runs, and applications with specific design requirements. Insert performance, however, remains closely tied to the AM process, insert material, injected material, part geometry, and injection molding parameters.
Where each AM process fits
Material jetting, also known as PolyJet, was the most frequently studied AM process for producing injection mold inserts. Its use may be linked to relatively short printing times and the ability to produce inserts with good surface finish.
Vat photopolymerization using UV laser curing, commonly referred to as stereolithography or SLA, was the second most studied process. The technology also offers good surface quality, making it suitable for design validation and short production runs.
Laser powder bed fusion using metal powders showed the strongest performance in terms of insert life. Reported maximum injection cycle counts reached 116 cycles for material jetting inserts, 85 cycles for vat photopolymerization inserts, and more than 500 cycles for metal laser powder bed fusion inserts.
Higher mechanical strength and better heat dissipation make metal AM inserts more suitable for higher-volume production. Surface roughness remains a limitation, and post-processing may be required.
Material extrusion, also known as FDM or FFF, has also been explored for insert production. Its use for functional injection mold inserts is more limited because of poorer surface finish and potential delamination.
Materials and molding parameters remain key constraints
Digital ABS, used with material jetting, was the most common polymer material reported for AM mold inserts. Its use was attributed to commercial validation for injection mold tooling, useful tensile properties, and heat deflection behavior.
Rigid 10K, used with vat photopolymerization, was also identified as a commercially recommended material for injection mold inserts. Other materials reviewed include high-temperature resins, tough resins, PEEK, ABS, PLA, PA6, ULTEM1010, steel, bronze alloys, aluminum, and titanium.
Despite this range of options, only Digital ABS and Rigid 10K were described as commercially validated or recommended specifically for injection mold inserts. Broader material combinations still require further testing before their performance can be clearly established.
Injection molding conditions were found to be critical to insert life. Injection pressure, mold temperature, and injection temperature were identified as the most important parameters affecting failure.
Polymer AM inserts are especially sensitive to these conditions because their mechanical properties are lower than those of metal inserts and can be affected by temperature. For this reason, the authors recommend minimizing injection and mold temperatures, flow rate, injection pressure, and holding pressure when using polymer inserts.
Short-run tooling, not a universal replacement
Rather than positioning additive manufacturing as a full replacement for conventional tooling, the paper frames AM inserts as a complementary option. The strongest fit is in short series, prototype tooling, temporary molds, and applications where complex geometry or faster iteration is required.
Reported applications include medical products, optical prototypes, cosmetics packaging, aircraft interior components, electronic enclosures, battery cell holders, and small commercial parts.
Most studies reviewed focused on relatively low-melting molded materials, particularly polypropylene. To establish broader feasibility, the authors suggest future work with higher-melting polymers, standardized cavity geometries, and more complex part designs.
Further research is also needed into mechanical properties beyond tensile strength, including compression, hardness, bending, and fatigue behavior under temperature conditions similar to injection molding. Conformal cooling channels and lattice structures were also identified as promising areas, particularly if polymer AM materials with higher thermal conductivity can be developed.
Viability depends on the use case
AM mold inserts can reduce lead times and enable complex insert designs that are difficult to manufacture with conventional CNC machining. Conformal cooling channels could also improve mold thermal management and reduce cycle times.
Even so, feasibility must be assessed according to the application. Material jetting and vat photopolymerization provide good surface finish but limited thermal performance and lower cycle counts. Metal laser powder bed fusion offers stronger thermal and mechanical performance but comes with higher costs and possible post-processing needs.
For manufacturers, the bottom line is that 3D printed mold inserts can work for specific injection molding use cases such as prototypes, short runs, and complex shapes. Success depends on matching the AM process and material to the expected production volume, molded polymer, part geometry, surface finish requirements, and molding conditions.
Resin tooling remains limited by durability and processing
Recent materials work points to the same constraint identified in the review. Formlabs, the Massachusetts-based developer of SLA and SLS 3D printers, recently introduced Tough 1500 Resin V2 and a second-generation Form Cure unit. The company said the resin brings 3D printed parts closer to the mechanical durability of injection molded components, while the curing system reduces post-processing times for engineering-grade resins to under 15 minutes.
That development reflects the broader push to close the performance gap between resin 3D printing and injection molding. For mold insert applications, however, the key question is not only whether a resin can approximate molded-part performance, but whether the printed insert can withstand repeated thermal and mechanical loading inside the mold.
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Featured image shows AM processes and materials evaluated for producing mold inserts. Image via Becerra-Borges et al.
