AS THE MARKET for environmentally friendly electric bikes grows, V Frames of Saalfeld, Germany, is using water-assisted injection molding (WAIM) to produce carbon fiber reinforced thermoplastic (CFRTP) e-bike frames that break from the usual aluminum frames made in Asia and provide a 68% smaller carbon footprint.
The reduced environmental impact, which was documented in an independent life cycle analysis by Johannes Kepler University of Linz, results from a combination of factors. “It’s the elimination of transport from Asia. It’s using recycled fibers, then at the end of life being able to recycle them again,” says Michael Mueller, CEO of V Frames. “It’s really the complete life cycle.”
V Frames is a spin-off of ISOCO Plastics Technology, GmbH, a German firm that specializes in injection molded plastic containers and pallets. In 2014, Mueller and colleagues from ISOCO with years of experience in traditional injection molding began discussing how they might apply the lesser-known WAIM process to a highend product.
“Water-assisted injection molding is a niche technology that has been in the automotive industry for a long time, but nobody really knows about it,” says Mueller.
Eventually, ISOCO decided to pursue CFRTP bicycle frames, a part that could benefit from the hollow tube geometry that WAIM can create. V Frames was founded in 2017 and began approaching e-bike OEMs to gauge interest in developing a CFRTP frame. “We didn’t get very far,” admits Mueller.
Accustomed to importing aluminum frames, the OEMs balked at the necessary investments in research, development and injection molding machines — especially for a new, unproven material. “The toughest thing was to prove to the industry that it was possible to do it,” recalls Mueller.
V Frames decided to fund its own research and development and produce a CFRTP frame as proof of concept. The journey took nearly eight years as V Frames and, later, the engineering consultancy LZS GmbH conducted simulations to ensure the frame had the right stiffness for a smooth ride and impact resistance for safety. Mold engineering for the complex part was also laborious.
The long design and testing period was necessary, says Mueller. “The most critical thing is to simulate, to develop the product, because then you build the mold for half a million dollars or more and you cannot change it really,” he says. “If the product comes out and it’s not working, you have problems.”
Once the Ecobike One proof of concept frame was completed in 2021, V Frames began working with several European e-bike OEMs to develop water-assisted injection molded CFRTP frames. Today, Buddy Electric X1s and ADVANCED® RECO e-bikes feature V Frames. A third company, ISOCO Bikes, now distributes the technology globally and sells V Frames and e-bikes.
V Frames are produced using a custom water injection molding machine that heats recycled carbon fiber and nylon 6 thermoplastic pellets until they are liquified and shoots the molten material into the machine’s steel mold. The mold is then cooled from the outside so that the outer walls harden but the center remains liquefied. Next, water is injected into the part to push out the liquid center and create the hollow tube geometry.
The entire process takes just 90 seconds. Afterward, the frames are moved to a six-arm robot that drills holes for fasteners, cuts and polishes WAIM overflow channels and injection points, and mills the WAIM entry section. Depending on the design, the robot can also insert metal inlays and assemble additional parts onto the battery area.
The LEHVOSS Corporate Group in Germany and Pennsylvania-based R & M International Sales Corporation supply carbon fibers for the bike frames, 90% of which feature short fibers. However, R&M spent 13 months developing a recycled long carbon fiber and Aegis® nylon 6 pellets for V Frames, including a patented process to coat individual continuous fibers.
“Our pellets performed really well,” says Stephen Rawson, a partner at R&M. “They flowed well. They gave a really good finish to the bike. So, V Frames was able to use a recycled product without the loss of properties. It was a really big win.”
CFRTP frames provide several advantages over aluminum frames, including a 10% weight reduction, part-integration, higher impact resistance and a smoother ride, according to Mueller. The efficiency of WAIM offers another benefit. V Frames can produce 1,000 frames per day with a single machine and operator. Once a machine and mold have been developed for a customer, the company can manufacture on demand — a rarity in an industry still struggling with supply chain delays. “You have to order aluminum frames one year before you get them delivered from Asia,” says Mueller. “Let’s say the demand increases or decreases. You can do nothing!”
But the biggest advantage may be the environmentally friendly production. Meuller says that V Frames are the first recyclable carbon fiber reinforced frame. “Most carbon fiber frames end up in a landfill. There’s no real technical solution,” he says. “This is simply another material. It can just be milled and reused.”
V Frames also produces water-assisted injection molded bicycle forks, cockpit components, mudguards, carriers and 28-inch wheels. In addition, the company is developing a wheelchair application.
Mueller believes that WAIM parts can be used for countless applications. With the ability to produce recyclable CFRTP products with complex, hollow tube geometries and integrated parts, the sky is the limit.
Melissa O’Leary is a freelance writer in Cleveland. Email comments to melissa@good4you.org.