To Yann Bakonyi, the Honda Monkey minibike is a global icon.
“Everybody knows the Monkey,” said Bakonyi, co-founder and lead designer of VIBA, a 5-year-old France-based motorcycle manufacturer with headquarters on the outskirts of Bourges and a design studio on the Bay of Biscay shores in La Rochelle.
Honda Motorcycle’s iconic Z series debuted in the early 1960s at an amusement park in Tokyo, Japan, and quickly made its way west through Europe and over to the U.S., evolving through numerous model updates, building a cult following, and inspiring emulators throughout the decades.
For that reason, Bakonyi wanted to put his own spin on the famed Monkey. And this past autumn he and his VIBA team finalized their minibike version using 3D printing technology.“It’s dedicated to people who like the original Monkey,” said Bakonyi, who studied at Strate School of Design in Paris and IAAD in Italy, “but are looking for something new – different than something else you can see on the streets.”
They branded the minibike as “Jane,” named after famous actresses such as Jane Fonda and Jane Birkin, who were at the height of their popularity in the 1960s and 1970s, the era in which the Monkey minibike was becoming famous in its own right. Establishing Jane as a limited-series release featuring a 125cc engine, VIBA will produce only 23 of the minibikes (two have already been complete), which officially hit the market on Jan. 10.
“[Fonda and Birkin] were bringing freshness, desire, and smiles to these years,” Bakonyi explained. “We wanted the same feeling for our Jane.”
Minibike parts by way of additive manufacturing
But VIBA wanted that freshness to come with the enhanced value of modern technologies and an innovative design process by way of additive manufacturing (AM) – and some German ingenuity.
After visiting the 3D Print 2018 Congress & Exhibition in Lyon last June, VIBA worked out a partnership with Lübeck, Germany-based SLM Solutions, a provider of metal-based AM technology, and 3D printing service provider Rolf Lenk Werkzeug- und Maschinenbau GmbH of Ahrensburg, Germany.
The decision to go the 3D printing route instead of the milling processes common in motorcycle manufacturing was a no-brainer for VIBA. “For us, doing some limited production run, it’s a great production method, because we can build all the parts we want with a good cost,” said Bakonyi.
At Rolf Lenk’s production center north of Hamburg, SLM offered VIBA three different 3D printers to use for a range of operational needs: the SLM®280, SLM 500, and SLM 800.
“For a limited series of a revamped product, the goal was to limit the amount of tooling setups or molds needed, which would be costly and add time to development,” said Ralf Frohwerk, head of business development¬¬ at SLM Solutions. “Lightweighting the bike was a design goal, and metal 3D printing was the logical solution.”
Besides the obvious benefits of an efficient process to produce complex and lightweight parts, Bakonyi craved something different than what VIBA used for its more traditional motorcycle product lines, Qora and Lara. He also wanted to avoid leaving 3D-printed parts at the prototype stage.
“At tradeshows we see a lot of [3D-printed] parts, but they are usually just for showcase and are not functional,” Bakonyi said. “So, this project was to show that 3D printing can be integrated in an industrial process to work perfectly.”
Together, VIBA, SLM Solutions, and Rolf Lenk designed and engineered various 3D-printed aluminum (AlSi10Mg) parts that were fully functional for Jane.
Printed on the SLM 280 machine were the gauge bracket (print time 2 hours, 50 minutes), which also combines the upper handlebar riser, and levers (2 hours, 40 minutes), which are hollow so that wiring can pass through to power LED turn signals. Printed on the SLM 500 machine were the front luggage rack (18 hours) and the front mudguard/headlight support (14 hours), which has a design inspired by the Voronoi diagram used in mathematic equations.
The levers and mudguard specifically would have been impossible to manufacture using traditional milling techniques.
“We are designers and are curious,” Bakonyi said with a laugh. “It makes you rethink how you design your parts and how to integrate engineering. For us, we like the challenge.”
3D-printed honeycomb fuel tank
But by far the project’s biggest challenge was engineering the minibike’s ground-breaking 3D-printed aluminum fuel tank, which VIBA believes to be the first of its kind.
While most minibikes are usually already fuel-efficient, the design of Jane’s fuel tank takes that capability to a whole different level with an internal honeycomb structure.
“It is the most innovative part because it’s the display of 3D printing added value,” Bakonyi said of the 1-mm-thick tank, which was printed on an SLM 800 machine over a 27-hour and 22-minute time frame. “You’ll find that almost everything possible has to do with this technology.”
The fuel tank was created using a selective laser melting (SLM) process, also known as direct metal laser sintering (DMLS) or laser powder bed fusion (LPBF), which uses a high-power-density laser to melt and fuse metallic powders together into a 3D part. And Jane’s fuel tank displays several benefits from the SLM process.
The main technical benefit, however, is the incorporation of functional optimization, said Frohwerk. The honeycomb design throughout the tank’s interior provides a baffle structure to help decrease fuel sloshing around in the tank during braking, acceleration, and turning, resulting in more stability for the minibike during a ride.
A reduction in the number of parts of the fuel tank was showcased because it was built as one piece, which eliminates welding seams. And tank features such as the push-up fuel cap were fused in along with aesthetic customization through the texturing of the exterior side panels.
“It really shows what’s capable with this technology,” said Frohwerk. “Designers can integrate functional features while creating new, custom designs.”
With its pioneering fuel tank design using AM, VIBA may have very well added a new chapter to the minibike narrative.
“We decided to reinvent the Honda Monkey because, every time we are building a project at VIBA, we care about telling a story,” said Bakonyi. “We wanted to revive childhood memories of riders.”
Photos courtesy of VIBA, https://viba-motor.fr