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Wilson Benesch benefits from AMRC Collaboration on metal Additive Manufacturing

Posted on 26/06/2019

Story of a British firm, their collaboration with Advanced Manufacturing Research Centre and implementation of AM.

Wilson Benesch is a British design and manufacturing success story. Now a medium sized company that was founded three decades ago, Wilson Benesch designs — and, notably, manufactures — high-end audio equipment in the UK. Among its many globally recognized and lauded brands, the company’s production of loudspeakers and turntables are very popular.

The company was founded in 1989 by Craig Milnes and Christina Milnes, who own and direct the company today, leading from the front, and it is located in Sheffield, South Yorkshire, a region with a considerable legacy in manufacturing and a significant investment in advanced manufacturing innovation today. With highly optimized operations Wilson Benesch has invested in advanced technology, research and development projects and its personnel, which includes a team of highly trained craftsmen, designers and engineers.

Collaboration

Even with three decades of success, achieved through innovation, R&D, investment in manufacturing technology and some government match funding, Wilson Benesch is a medium sized company that would struggle to find the funds necessary to invest in metal additive manufacturing (AM), a technology that can demonstrably add value to some identified applications. Understanding this, the company has worked in a collaborative way with the Advanced Manufacturing Research Centre (AMRC), one of seven High Value Manufacturing Catapult centres in the UK, to further support innovation within the company and utilize advanced manufacturing processes that would otherwise not be available to the team.

The end-to-end solution involved a series of process stages, including:

• Reverse Engineering
• Design / Re-design
• Digital thread
• Optimization
• Prototyping (SLA)
• Simulation
• Production

Identifying Applications for AM

Successful outcomes with AM are dependent, to a large extent, on identifying products / parts / components that are are good match with the process, and then designing for the process. The collaboration between Wilson Benesch and the AMRC identified three suitable applications for metal AM, based on recognising the considerable potential for creating highly optimized structures that benefited from both advanced materials technology and the manufacturing process itself. A key objective specified within the resulting project was to develop improved functionality of the three product parts including the control of resonant energy in these structures.

Wilson Benesch worked with the Design and Prototyping Group (DPG) at the AMRC on the design to improve functionality and performance by incorporating unique features. These features ultimately added value to the end product and improved the aesthetics — all key tenets of the Wilson Benesch mission.

This project achieved all the above and maximized the benefits of AM, specifically the ability to produce complex parts that were not otherwise manufacturable, and consolidating the number of parts, to reduce assembly.

The Tonearm / Mount

The function of a tonearm within an audio system is to support the cartridge in the correct position (consistent height and angle) over the record and allow it to move inward to the centre of the record, while applying the correct amount of weight to the stylus and ensuring that anti skate force is present. The tonearm also holds the cabling that transmits the signal from the cartridge out to the rest of the system. Due to the nature of the operation of the tonearm, with the bulk of the weight at either end (the cartridge at one end and the counterweight that balances it at the other), the body of the arm necessarily needs to be stiff and strong, as any flex or movement in the tube while the cartridge is on the record will result in audible interference and inferior sound. However, to function, the overall mass of the tonearm has to remain low and lightweight materials are fundamental. The mount for the tonearm is also vital to its operation, and must also house the cabling to improve sound output, requiring complex internal channels.

Project engineers Abdul Haque, Luke Hill and Daniel Tomlinson worked on the project alongside project manager Marcus Crossley and Head of Strategy for Near Net Shape Processing at the AMRC, James Hunt.

With a dual design approach focused on functionality and aesthetics in line with the Wilson Benesch brand, the complexities of the new tonearm and mount were well aligned with the capabilities of metal AM. According to Luke Hill: “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. We used the capabilities of selective laser melting AM with Ti-6Al-4V powder to create an internal through channel to feed a wire through the back of the tonearm.

“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. 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.”

The use of AM also saw the mount’s part count reduced from fifteen down to just two.

Spheres — Really?

The steel spheres Wilson Benesch uses for its sound systems were another part of this project. This might seems like an odd one – in that a sphere is a sphere! However, the 500g steel spheres were redeveloped to strip away unnecessary material and weight, while also improving performance.

Luke Hill commented: “When we evaluated the existing steel ball design, we realized that it was a smart solution but it wasn’t actually particularly weight efficient as far as load transfer goes. After running topology optimization and structural simulations, it was clear that what we really needed was a cylinder to transmit the energy in the ceiling to floor direction.

“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.”

In terms of efficiency, when compared with conventional machining methods, AM proved to be a less wasteful option for the complex parts created within the project as it used a very high percentage of the material to create the final part and was more flexible.

He added: “Additive manufacturing brings the flexibility desired by manufacturers because of the ability to quickly and iteratively make design improvements without requiring tooling changes or involving different processes, but simply changing the CAD model and sending it to print on the machine.”

In all, the Wilson Benesch project highlights the benefits of metal AM as an enabling technology for a medium sized company that might otherwise let these benefits pass by. It also showcases the capabilities of the AMRC, working collaboratively from conceptual design through to final production with SMEs.

Commenting on this, James Hunt said: “In having the facilities here available for companies and SMEs to come and try, it allows them to de-risk the activities so they don’t have to go and buy a piece of equipment at £500k without a clear understanding of what the technology can do.

“As can be seen through this process, it’s not just a case of sending a drawing and someone printing it off, there is a development cycle that in turn feeds an understanding of how the process works so that the new parts fit the process better. So having the expertise within the ARMC to be able to offer that as service is of great benefit to companies.”

Craig Milnes, design director of Wilson Benesch, said: “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.”