The announcement that Empire Cycles, along with Renishaw, had created the world’s first 3D printed mountain bike, the MX6-R, is testament to the ingenuity of modern manufacturing engineers and designers. Creating a complete titanium frame using additive manufacturing is a major milestone not only for the technique itself, but also for the world of serious mountain biking. However, the project also needed the help of some more traditional techniques to bring the project to a successful conclusion.
Empire Cycles required the extensive input of a its machining and cutting tool partners, Merlin Engineering (Bolton) and WNT (UK), who formed a vital part in the completion of the process. The reason being is that while additive manufacturing has developed significantly, precision machining is still required to finish safety critical and fine tolerance elements of the cycle frame. “The machining of these components was vital to the success of the project, as the additive manufacturing is not able to achieve the tolerances required for the bearing locations in areas such as the headstock and crank. Simply put, without the precision machining expertise of WNT (UK) and Merlin there would be no bike,” says Chris Williams, Empire Cycles Managing Director.
The use of additive manufacturing, or 3D printing, threw up its own particular challenges when it came to machining these frame components as the whole idea was to reduce the weight of the frame, which meant that the amount of material left for machining was minimal, as little as 2 mm in some areas. This meant that WNT had to rethink some of its machining strategies as Scott Bradley, WNT’s Technical Sales Engineer working on the project, explains: “Conventional thinking when it comes to machining titanium is that climb milling is the optimum process, as this helps to get through the tough skin of the material. However, at WNT we have been carrying out in-depth cutting trials in preparation for this particular project and the conclusion was that due to the clamping of the part and the thin wall thicknesses that conventional milling provided the best option to semi finish the part, with climb milling used only for the finishing cuts.”
To maximise machining performance WNT selected its 2011 series of indexable insert cutters that have been developed as an alternative to solid carbide mills at diameters between 16 and 40 mm diameter (although the range extends to 80 mm diameter). With their soft cutting action and radial force compensation features, they are the ideal solution to thin walled components being machined on machines with high speed, low powered spindles. The inserts used on the frame being machined at Merlin Engineering were selected specifically for the application. For the headstock area WNT selected an insert developed specifically for machining titanium, with an insert developed for machining super alloys being selected for the bottom bracket of the frame.
After machining the frame components were bonded together and the bike completed with the addition of wheels, hubs, brakes, chain rings, and pedals supplied by Hope Technology. “We have worked closely with Empire Cycles for many years, helping with the machining of the frames on the original MX-6 cross country bike from solid aluminium. The creation of this world’s first high performance cycle frame using additive technology is a major milestone in manufacturing. However, it is reassuring that precision metalcutting techniques are still vital to the creation of the finished article and make the whole process practical,” says Tony Pennington, Managing Director, WNT (UK).
Issued on behalf of:
WNT (UK) Ltd
Sheffield Airport Business Park
Tel: 0800 073 2 073
Fax: 0800 073 2 074
Mr Tony Pennington