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ORIGINAL RESEARCH ARTICLE

Fused granular fabrication of conformally cooled injection molding tools

Abdullah Riaz1,2* ,  Pedram Azizi1,3 ,  Naga Anvesh Gutta1 ,  Mohamed Hamouda1 ,  Tim Dreier1 ,  Alexander Ahrend1 ,  Philip Töllner1 ,  Hermann Seitz1,4
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1 Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany
2 Institute of Physics, University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany
3 Faculty of Computer Science and Electrical Engineering, University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany
4 Department of Life, Light and Matter, University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany
MSAM, 026040006 https://doi.org/10.36922/MSAM026040006
Received: 20 January 2026 | Revised: 3 March 2026 | Accepted: 5 March 2026 | Published online: 28 May 2026
© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
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Abstract

Injection molding (IM) is widely used for high-volume, small, and complex plastic components and is increasingly applied to ceramic and metallic parts. However, the high cost and long processing times of conventional tooling hinder its application in prototyping or small series production. Conventional molding tools with straight-drilled channels cool unevenly, causing shrinkage differences and longer cycle times. This study focused on material extrusion-based composite extrusion modeling three-dimensional (3D) printing of large-scale IM tools using metal IM feedstock. Conformal cooling channels were integrated into the tools to enhance cooling efficiency and temperature uniformity, reducing residual stress and defects. Large-scale IM tools were successfully fabricated via composite extrusion modeling 3D printing for the first time, achieving high green and sintered densities of 97.37 ± 0.24% and 98.08 ± 0.10%, respectively, without any visible cracks or delamination. Dimensional accuracy remained within ~0.7 mm, and surface roughness was comparable to that of conventional IM tools. Nevertheless, post-processing is required to address surface waviness and support removal marks. Simulations also demonstrated that conformal-designed tools cool molded parts below 80 °C in 5 s, compared with 20 s for conventional tools. These findings demonstrate the potential of material extrusion-based 3D printing as a cost-effective alternative for producing IM tools with conformal cooling, enabling faster production cycles and more efficient design for fragile geometries.

Graphical abstract
Keywords
Fused granular fabrication
Injection molding tools
Conformal cooling channels
Temperature distribution simulations
Density and dimensional accuracy
Funding
This work was funded by the Federal Ministry for Economic Affairs and Energy (KK5037202WO0).
Conflict of interest
The authors declare there is no conflict of interest.
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Materials Science in Additive Manufacturing, Electronic ISSN: 2810-9635 Published by AccScience Publishing
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