
3D metal printing made its appearance on the world stage just a few short years ago. However, it has already begun to revolutionize the manufacturing industry – with big companies like DIY Rockets, General Electric, Boeing, Ford, and Rolls-Royce using the process to create metal components. With its low-cost and high-speed benefits, it is no surprise that 3D metal printing is also starting to leave its mark on the welding industry. Currently, 3D printers with robotic welding arms are being used to create items that are highly functional and awe inspiring.
A team of students at the Delft University of Technology (TU Delft) in the Netherlands is showcasing the multifaceted capabilities of welding-based 3D printers. The team combined advanced robotics, the mechanics of 3D printing, and the visual qualities and strength of welding to create the very first steel bicycle to be produced with this unique process. The specially-made stainless steel bicycle is called the Arc Bicycle. To create this never-before-seen bike, the TU Delft students worked with MX3D, the Amsterdam-based company that introduced the Mataerial 3D Printer in 2013.
The Mataerial 3D Printer differs from traditional 3D printers in several ways. First, it’s not limited to horizontal surfaces. Due to its flexible, robotic arm, the Mataerial 3D Printer discharges resin from any angle onto any surface – whether vertical or horizontal. Second, traditional 3D printers can only lay very thin sheets of resin onto their surfaces. In contrast, the Mataerial 3D Printer extrudes thick, worm-like columns of resin that jut from the surface outward, into mid-air, without any support structures. Last, but not least, the Material 3D Printer is capable of creating more complicated structures than traditional printers. The columns of resin can be curved, twisted, and linked as it’s being ejected, leaving behind beautiful, yet sturdy, structures.

The Arc Bicycle was made using a more recent MX3D printer that actually ejects molten metal, rather than resin. To begin the process, the design for the welded structure is inputted into the printer’s software. This gives the sophisticated robotic arm the commands it needs to create the design. For the frame of the bike, the TU Delft team of students chose a complex, modern lattice design. After the design is inputted into the printer, the robotic arm ejects molten metal onto the desired surface, and it continues to do so as it moves away from the surface. This movement results in long, worm-like columns that take only seconds to harden. The speed at which the molten metal cools eliminates the need for support structures. In fact, seeing the robotic arm in action looks like “drawing in mid-air,” said team member Stef de Groot. With fine control and exact precision, the sophisticated robotic arm will create each unique lattice structure according to specifications. Once cooled, the individual lattice structures are welded by hand using the gas metal arc welding process. The finished product is a fully-functional bike with a design that is unique and breathtakingly beautiful.
The Arc Bicycle is reported to weigh about as much as a traditional steel-framed bike. And for those of you wondering if the Arc Bicycle can stand up to rougher terrain, the bike is capable of withstanding the uneven cobblestone streets of Amsterdam. For these students, the Arc Bicycle is a product of unquestionable usefulness. Bicycles are extremely popular in the narrow streets of the Netherlands, where driving a car is an inconvenience. “It was important for us to design a functional object that people use every day,” said Stef de Groot. “Being students in the Netherlands, a bicycle naturally came to mind. A bicycle frame is a good test for the technology because of the complex forces involved.” However, MX3D isn’t restricting this technology to creating bikes and similar consumer products. The company is already using the technique to build a pedestrian bridge, but continues to seek future applications for their welding-based 3D printing technology.
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