MX3D and Takenaka Corporation Present Strong Test Results on a Series of 3D-Printed Structural Steel Connectors

Amsterdam, 9 February 2021 – Large-scale 3D metal printing company MX3D has successfully produced a structural connector in duplex steel, designed in collaboration with the engineers of Takenaka, one of the largest architecture, engineering, and construction firms in Japan. This project showed the progress in the production of highly customized and engineered steel connectors using robotic 3D metal printing, i.e. Wire Arc Additive Manufacturing (WAAM). Now, destructive and non-destructive testing on a series of printed duplex steel connectors shows strong and consistent performance on mechanical and material properties. The successful tests are a crucial step towards certification of the structural connector, which parties intend to use for innovative building projects.

In 2019, Takenaka Corp. and MX3D have initiated a collaboration to explore the possibility of robotic WAAM technology in the production of large customized steel connectors for the infrastructure industry. The goal of the project is to automate both the design and production of complex connectors for large structures in the building industry. As the complexity of structures increases, skilled labour is scarce and build speed is key, such innovation is much required. Following the successful production of the first connector prototype (link), the collaboration focused on mechanical and material properties testing, a crucial requirement for acceptance by the market.

Destructive testing on a series of printed structural connectors showed strong and constant mechanical and material properties, paving the way to certification. Tensile tests, fatigue tests and buckling tests performed on the connectors showed convincing results. CT scans relieved the interior was dense and solid. Moreover, compressive failure tests confirm the clear effect of mortar filling on buckling resistance and ultimate strength. A 4mm-thick connector filled with mortar has approximately the same strength as an 8mm-thick connector (2.2 kN vs. 2.3 kN resp.), reducing 50% of required material making the freedom of form that 3D metal printing offers even more advantageous. The material properties and mechanical testing achieved desired specs and consistency, establishing the relevance of robotic 3D printing to the industry.

The series of connectors has been printed in duplex stainless steel, as the initial prototype (link). The alloy is renowned for its good mechanical properties and excellent corrosion resistance, ideal for structural applications. The hollow steel structure filled with concrete is highly effective and economical for safety performance, where the other steel bears bending and tensile forces and the inner concrete core delays or prevents local buckling of steel.

Researchers from Takenaka Corp. used information from physical testing of material specimens to generate a FE simulation model and assess the mechanical behaviour of the connectors. These results have been tested against real-life behaviour of the connectors undergoing compressive load. As the picture below shows, the results provided by the simulations were very close to the behaviour shown during the mechanical tests. Furthermore, tensile strength tests showed a highly consistent pattern, required for architects and engineers to include this technology in their tool kit. The full research will be published soon.

Following the successful fabrication of the optimized and printed structural steel connectors and the strong test results, the partners involved intend to implement the bigger version(s) in an actual building project.

Closing the digital design loop is key for the architecture, engineering and construction industry. MX3D’s robotic WAAM technology used to produce these connectors allows for full digital control over the design, production, timeline and cost with great logistic benefits and excellent integration with BIM applications. MX3D’s MetalXL now enables fabricators to quickly start 3D metal printing large-scale metal applications in their own facilities.

The strong mechanical and material results from the research project confirm the relevance of robotic 3D metal printing for architecture, engineering and construction and open up a new generation of structural connections for the AEC industry.

Note: send an email to to receive the research paper soon.

“Ever since we’ve realized the first 3D printed metal bridge, our robotic WAAM technology has received a lot of attention from construction companies. The collaboration with Takenaka Corporation on this project and its impressive test results represent yet another leap forward in the adoption of 3D printed components in the AEC industry.” Filippo Gilardi – Lead R&D Engineering at MX3D

Takenaka has further developed our excellent collaboration with MX3D and conducted a series of comprehensive research and experiments on WAAM steels’ performance. We believe this would be a significant step towards the deployment of WAAM technologies in the AEC industry. Takuya Kinoshita – Project Leader at Takenaka

Project Team
Project Development:
Filippo Gilardi, MX3D
Takuya Kinoshita, Takenaka Corporation

MX3D Engineering team:
Jean-François Moulin, Process Engineering + Material Engineering
Juri Weber, Production Engineer

Takenaka Engineering team:
Fumiaki Osuga, Structural Engineering
Yasuhiko Inoue, Material Engineering
Naoko Nakashima, Material Engineering

MX3D Takenaka Connector – Optimized + Printed Structural Steel Connector
MX3D, the robotic 3D metal printing pioneer, produced a structural steel connector, designed in collaboration with the engineers of Takenaka, one of the largest architecture, engineering and construction firms in Japan. The project shows the progress in the production of highly customized and engineered steel connectors using robotic 3D metal printing, i.e. Wire Arc Additive Manufacturing (WAAM). The steel connector’s net weight is 40kg reaching up to 45kg after its hollow core was filled with approximately 2.5 litres of mortar. MX3D has 3D printed the connector using Duplex steel, an alloy renowned for its good mechanical properties and excellent corrosion resistance, ideal for structural design.

Project information: Video:

TAKENAKA Corporation // Dreams into reality for a sustainable future
With yearly sales of $10 billion, 20 overseas offices and over 1,000 architects in its design department, Takenaka Corporation offers comprehensive services worldwide across the entire spectrum of space creation from site location and planning to design and construction as well as post-completion services such as building maintenance.

Takenaka aims to create works that will be the “best” not only in the current era but also in the next era, and beyond. Our mission is to provide customers with a better space through both building design and construction.

MX3D // Robotic 3D Metal Printing
With over 15.000 kg of metal 3D printed parts and over 50 man-years of experience since 2014, MX3D is the company that brought large-scale robotic wire arc additive manufacturing (WAAM) and its industry relevance to life and enabled 3D metal printing to be more flexible, faster and cheaper.

With the release of MetalXL, MX3D transforms industries further by enabling companies, engineers and designers to print industrial 3D metal parts in-house themselves.

MX3D became an immediate innovation leader in 3D metal printing by presenting its jaw-dropping 12-meters long fully functional 3D printed stainless steel pedestrian bridge which will soon be installed in the heart of Amsterdam.

Selected MX3D Projects:
MX3D Bridge: 12.5 meters fully printed stainless steel bridge
– collaboration with 30+ global partners
– project information (link)
– video of production (link) and completion (link)
– follow-up on MX3D Smart Bridge (link)

Robot Arm: optimized, printed and installed industrial spare-part
– collaboration with Altair and ABB
– project information (link)
– video of production (link) and installation (link)

Takenaka Connector: printed structural steel connector
– commissioned by Takenaka, a top-5 Japanese construction firm
– project information (link)
– video of production (link)

Arc Bike I and II: two eye-catching printed bike
– arc bike I: dot-printing technology: information (link) + video (link)
– arc bike II: aluminium print: information (link) + video (link)

Source: MX3D

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