Renishaw collaborated with a leading British bicycle design and manufacturing company to create the world's first 3D printed metal bike frame. Renishaw is the UK's only manufacturer of metal-based additive manufacturing machines that print metal parts.
Empire Cycles has used Renishaw's additive manufacturing technology to design the mountain bike, creating a titanium frame that would be both strong and light using topological optimisation; the new frame is about 33% lighter than the original and has been additively manufactured in titanium alloy in sections and bonded together.
Key advantages for this design include design freedom that allows rapid iterations with flexibility to make design improvements right up to production, ability to make shapes derived by topological optimisation, and ultimate customisation and tailoring, making one-offs as easily as production batches.
In terms of construction advantages, the design allows complex shapes with internal strengthening features, hollow structures, and built-in features such as the rider's name. The use of titanium alloy offers performance benefits such as the seat post bracket being 44% lighter than the aluminium alloy version; extreme strength tested to EN 14766, and corrosion resistance and long lifespan.
Renishaw and Empire Cycles worked together on the 3D printed bike to optimise the bicycle design for additive manufacture, eliminating many of the downward facing surfaces that would otherwise have needed wasteful support structures.
Titanium alloys have a high Ultimate Tensile Strength (UTS) of more than 900 MPa when processed using additive manufacturing, and near perfect densities of greater than 99.7% are achieved. The seat post bracket was tested using the mountain bike standard EN 14766, and was able to withstand 50,000 cycles of 1200 N. Testing continued to six times the standard without failure.
Topological optimisation uses iterative steps and finite element analysis to remove material from areas of low stress until a design optimised for load bearing is evolved. The resulting model is both light and strong. The historical challenge in manufacturing these shapes can now be overcome with additive manufacturing, enabling physical 3D models to be realised.
Thanks to additive manufacturing, and the use of titanium alloys instead of aluminium alloys, the bike frame weighs 1400g instead of the original 2100g.
Managing Director at Empire Cycles, Chris Williams had already produced a full size 3D printed replica of his current bike before he approached Renishaw.
Renishaw originally agreed to optimise and manufacture the seat post bracket only, but after this proved successful, decided the whole frame was a practical goal. Chris updated his design with guidance from Renishaw's applications team on what would build well, and the frame was sectioned so that it would fully utilise the AM250's 300mm build height.
By constructing the bike using the additive manufacturing process, Empire Cycles has benefited from several performance advantages including achieving a pressed steel ‘monocoque' design used in motorbikes and cars, without the investment in tooling that would be prohibitive for a small manufacturer. The company can also carry out continual design improvements as no tooling is required. Additionally, since the component cost is based on volume and not complexity, some very light parts will be possible at minimal costs.
Research into bonding methods resulted in Mouldlife providing the adhesive, and technical specialists 3M providing test facilities. The wheels, drive train and components required to finish the bike were provided by Hope Technology Ltd.
This project has highlighted that excellent results can be achieved by working closely with the customer.
The Empire Cycles 3D printed bike can be seen at the London Bike Show (Empire Cycles stand LB1020) from 13th to 16th February; and the London Science Museum (Antenna Live 3D printing event) from 18th to 20th February.