A team from the Design and Prototyping Group at the University of Sheffield Advanced Manufacturing Research Centre (AMRC) was recently approached by audio company Wilson Benesch, Sheffield, UK, to produce a selection of components for its products using metal Additive Manufacturing, with the aim of optimising the control of resonant energy in these structures.
The components include a tonearm mount for a record player, fluted cups to fit between the shelves and carbon fibre bars on a Hi-Fi rack, and load-bearing steel spheres to be located at the corners of each section of the rack to isolate the shelves. Abdul Haque, Luke Hill and Daniel Tomlinson, Project Engineers in the AMRC’s Design and Prototyping Group, worked on the project alongside Marcus Crossley, Project Manager, and James Hunt, Head of Strategy for Near Net Shape Processing at AMRC.
To produce the tonearm mount, the team was initially provided with a clay model of Wilson Benesch’s tonearm mount design, which it was able to reverse engineer using a CT scanner to create an image that was uploaded and interpreted to create a new CAD part geometry. “When we created a form Craig was happy with and that we were confident could be manufactured using Additive Manufacturing processes, we could continue with the detailed design work ensuring the tonearm would fit the Wilson Benesch system requirements,” explained Hill.
The team produced the tonearm using Laser Powder Bed Fusion (LPBF) with Ti-6Al-4V powder, and incorporated an internal channel through the structure to allow a wire to be fed through the tonearm when installed on the record player. “This is something unique, and as far as performance goes is an ideal solution because Wilson Benesch wanted to create a vacuum within the tonearm,” Hill added.
“They also specified a tight tolerance between the component and the mounting point, but they needed to feed a wire through somewhere, so this was a perfect approach. The internal wiring keeps the tonearm aesthetic uninterrupted and organic and the wire is not trailing about, so it will not get tangled or spoil the appearance.” Using the opportunity for part consolidation offered by design for AM, the team was also able to reduce the mount’s part count from fifteen parts to two.
The load-bearing steel spheres, each weighing 500 g, were also redeveloped, with the team optimising the design to minimise material use and weight while improving performance. “When we evaluated the current steel ball design, we realised that it was a smart solution but it wasn’t actually particularly weight efficient as far as load transfer goes. After running topology optimisations and structural simulations, it was clear that what we really needed was a cylinder to transmit the energy in the ceiling to floor direction,” Hill continued.
“That meant we could strip a lot of weight out and therefore increase the specific performance by using the high-stiffness titanium alloy material more efficiently. Then we added through-channels which have an energy dissipation perspective to them that stripped out further weight.”
Craig Milnes, Design Director, Wilson Benesch, stated, “James and Marcus, along with the DPG engineers, Abdul, Luke and Daniel have been invaluable in this project, allowing Wilson Benesch to push through design concepts into finished prototype components that extol all of the virtues of the Wilson Benesch brand. That is to say, conceptually unique, technologically and materially advanced, aiding the ultimate goal of advancing the state-of-the-art in audio design and high fidelity music reproduction.”
“Wilson Benesch has collaborated consistently with centres of excellence in engineering, design and manufacturing since the foundation of the company,” added Christina Milnes, Managing Director of Wilson Benesch. “Indeed this is one of a number of projects that we have worked on with the Advanced Manufacturing Research Centre since the centre was established in 2001. Having access to this kind of technology is a major asset.”