The Future of Tool Manufacturing with Metal Additive Technologies

Metal AM is reshaping how dies, molds, and cutting tools are produced — but process-induced defects remain the critical challenge. Understanding how porosity, residual stress, and cracking affect tooling alloys is key to unlocking industrial adoption.

Metal additive manufacturing (AM) is increasingly used for producing tooling components such as dies, molds, and cutting tools due to its ability to fabricate complex geometries and near-net-shape parts. However, the performance of additively manufactured tooling alloys is strongly influenced by process-induced defects including porosity, residual stresses, and thermal cracking.

A comprehensive review examines how process parameters and material selection affect the microstructural integrity and mechanical behaviour of tooling alloys produced using metal AM technologies. The discussion focuses primarily on major AM processes including Powder Bed Fusion (PBF), Directed Energy Deposition (DED), Binder Jetting, and Material Extrusion.

Process Parameters and Their Impact

Parameters such as laser power, scanning speed, hatch spacing, and layer thickness directly influence melt pool stability, solidification behaviour, and thermal gradients during fabrication. Improper parameter selection can result in lack-of-fusion defects, gas porosity, residual stress accumulation, and microcrack formation.

Crack Susceptibility in High-Hardness Alloys

A major challenge identified is crack susceptibility in high-hardness tooling alloys, particularly H13 tool steel. Rapid heating and cooling cycles during AM generate steep thermal gradients that promote solidification cracking and microstructural instability. In contrast, maraging steels demonstrate improved processability due to lower crack sensitivity and favourable precipitation-hardening characteristics.

Defects and Mechanical Performance

The review also highlights the influence of porosity and microstructural defects on hardness, wear resistance, fatigue behaviour, and tensile properties. Defect formation significantly reduces mechanical reliability and dimensional accuracy, making process optimisation critical for industrial tooling applications.

Post-Processing Solutions

Post-processing techniques such as heat treatment, hot isostatic pressing (HIP), and laser remelting are discussed as effective methods for reducing porosity, relieving residual stresses, and improving mechanical performance. Although significant progress has been achieved, challenges remain in process repeatability, defect mitigation, and quality consistency across different tooling alloys and AM platforms.

The Path Forward

Overall, the study demonstrates that controlling porosity, crack formation, and microstructural evolution is essential for improving the mechanical performance and industrial adoption of additively manufactured tooling alloys. As process understanding matures and post-processing capabilities improve, metal AM is set to play an increasingly central role in the future of tool manufacturing.