Manufacturers typically construct production model frames from steel or aluminum. While steel weighs more than aluminum, the material delivers cost benefits for the producer and a more rigid chassis for the rider. However, if brands could negate the weight gain that comes with steel, they could have the best of both worlds.
That’s exactly what Madrid’s Nebrija University set out to do when it partnered with multinational iron and steel company ArcelorMittal. By pairing Nebrija University’s intelligent design developments and competition vehicle experience with ArcelorMittal’s R&D might and additive manufacturing technology, the project established a new method for fabricating a tubular steel trellis frame: 3D printing.
"We had more or less achieved the new shape with our algorithms,” admitted Nebrija University Mechanical Engineer Sergio Corbera. “The possibility of generating hollow parts was the main unknown in metal 3D printing. We are talking about wall thicknesses of between 0.8 and 1 millimeter in the chassis.”
Producing those 0.8-1mm hollow steel tubes was the first hurdle of the partnership, but steel presents the perfect material for such a lightweight construction, as aluminum and titanium don’t maintain the same structural integrity at such a reduced thickness. When the engineers determined that the 3D-printed tubes were structurally sound, the team integrated the data into the algorithm, allowing the system to automatically create stable geometric shapes.
"The simulations seem to indicate that we have achieved a very balanced chassis that allows a very good behavior of the bike on the circuit,” revealed Corbera. “We have applied a new manufacturing technology (3D printing) for this sector with a material that could look like prior relegated to that industry and with geometric shapes that break with the usual",
Project leads also stressed that the team didn’t need to develop a new steel alloy for the 3D printing process to achieve success. The partners used standard powdered steel for the additive manufacturing technique, which should allow manufacturers to produce 3D-printed frames without having to develop a proprietary blend of metals. On the other hand, brands like Honda already have 3D-printing initiatives and can further develop the alloy to gain even more structural or cost advantages.
“Our steel frame weighs around 3.8 kilos," noted ArcelorMittal R&D Engineer Paula Rodriguez. "A high-grade aluminum frame from the major motorcycle manufacturers doesn't drop below 5 kilos, while the other steel frames are around 6/7 kilos. It seems like a small difference, but on a piece like this it's a huge saving.”
