Additive Manufacturing Breakthrough Extends Service Life of Large Die Casting Tools
The Fraunhofer Institute for Laser Technology ILT, in collaboration with MacLean-Fogg and Toyota, has demonstrated a significant leap forward in additive manufacturing for die casting tools. By combining a newly developed tool steel with a scalable Laser Powder Bed Fusion system (PBF-LB/M), the project team has produced a hybrid, large-volume tool insert for the transmission housing of the Toyota Yaris Hybrid—bringing conformal cooling and extended tool life into industrial-scale production.
Meeting Automotive Manufacturing Demands
The automotive industry faces increasing cost pressures and a shift toward electromobility. Manufacturers are reducing the number of stamped parts and pursuing fewer, but more complex, aluminum structural components. This places extraordinary demands on die casting tools, which must be larger, more robust, and thermally resilient, while allowing rapid adaptation to new geometries.
Traditional die casting molds struggle to meet these requirements. Conventional tool steels such as H11, H13, or M300 often suffer from cracking, thermal distortion, and reduced durability when used in large-format additive builds. Additionally, standard PBF-LB/M machines lack the build volume required for inserts exceeding 600 x 600 mm².
Scalable Additive Production with L-40 Steel
To address these limitations, Fraunhofer ILT developed a gantry-based, five-laser PBF-LB/M machine with a build volume of 1,000 x 800 x 350 mm³. The system employs a movable processing head and localized shielding gas guidance, enabling scalability along the machine axes while maintaining stable process conditions. A heated substrate platform—reaching 200 °C—further reduces thermal stresses, mitigating cracking risks in large builds.
Central to the success of this project is the L-40 tool steel from MacLean-Fogg, engineered specifically for additive manufacturing. L-40 delivers high hardness (48 HRC), tensile strength (1420 MPa), and notched impact strength (>60 J), while showing a much lower tendency to crack during both the build process and subsequent heat treatment.
“The key to success lies in the L-40 material from MacLean-Fogg, which is tailored to the requirements of PBF-LB/M,” explains Niklas Prätzsch, Group Leader LPBF Process Technology at Fraunhofer ILT.
Hybrid Tool Production for Industrial Application
The project team applied a hybrid production approach, combining conventionally manufactured preforms with additively built sections. The gearbox housing tool insert produced for Toyota integrates near-contour cooling channels impossible to achieve using conventional machining. These cooling structures significantly lower thermal loads in critical zones, extending service life—by up to four times compared to conventional H13 molds in earlier projects.
After additive manufacturing, the tool insert underwent stress-relief annealing before receiving precision milling on functional surfaces. Due to the dimensional accuracy of the additively built base, only light finishing was required.
A Step Toward Giga Casting
The results point to a new era of die casting mold production. Conformal cooling reduces wear and extends tool life, while additive manufacturing shortens lead times by eliminating lengthy machining and assembly steps. Hybrid methods further reduce cost by applying additive processes only where design complexity demands.
“With L-40, we set out to break the limits of additive manufacturing for hot and cold forming tools in general and die casting tools specifically,” said Harald Lemke, Director of Product Management, MacLean-Fogg Component Solutions. “This project proves that it’s possible to produce large, complex and highly durable inserts technically and gives clear milestones to reach to be economically attractive. Additive manufacturing is ready to take on real industrial-scale challenges.”
Beyond Automotive
While the immediate focus lies in high-pressure die casting for large automotive aluminum components, the process chain developed – large-format LPBF system, advanced tool steel, and hybrid production – holds potential for broader applications. Industries requiring heavily loaded tools with complex cooling structures and short development cycles, such as plastics processing and composite manufacturing, stand to benefit.
For OEMs like Toyota, these developments promise faster tool development, longer tool lifetimes, and greater design flexibility – paving the way for efficient, durable tooling strategies aligned with the future of electrified mobility.
For more information: www.ilt.fraunhofer.de
