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Robots slash magnet placing times from one hour to 55s

11 February, 2021

UK engineers have used robots to cut the time it takes to place powerful magnets in electrical generators from one hour to just 55 seconds. The development work was done by automation experts at the University of Sheffield’s Advanced Manufacturing Research Centre (AMRC) as part of a project called Robomag.

The project was designed to tackle a problem that the Sheffield-based magnetic gearing specialist Magnomatics encountered when locating powerful permanent magnets in the rotors of 6m-diameter generators designed for use in offshore wind turbines. Doing this by hand is a painstaking process in which operators use jigs and leadscrews to carefully slide 204 magnets – each weighing 18kg and capable of exerting forces of up to 3kN – into position.

The procedure is time-consuming and difficult due to the forces generated by the magnets when they are placed near a generator’s steel hub. It can take two operators up to an hour to place each magnet, and the process also poses potential dangers to them because of the risk of body parts being trapped when the magnets “snap” into place.

Magnomatics, formed in 2006 as a spin-out from the University of Sheffield, was one of seven companies to win funding last year from the Offshore Wind Growth Partnership to develop advanced technologies to cut the costs of offshore windpower. Without automating some of the processes involved in assembling large turbine generators, it is difficult to make them cost-competitive.

Magnomatics is working with an industrial partner to scale up the required technologies, initially for offshore wind turbines up to 5MW, before moving on to machines rated at 15MW or more. The developments are based on the company’s high-efficiency, high-torque-density Pseudo Direct Drive (PDD) generator technology which is aimed at high-torque, low-speed applications.

To automate and speed up the process of placing the magnets, Magnomatics teamed up with the AMRC. “By creating a practical demonstration of robotic magnet placement we’ve been able to show the huge gains to be made, reducing the time it takes to position each magnet from nearly an hour to just 55 seconds, and there is potential to reduce the time even further,” says the AMRC’s Dr Alexei Winter.

As well as cutting the rotor build times and enhancing personnel safety, the project reduces the need for bespoke tooling. The cell can be programmed to build rotors with different combinations of magnets, thus saving even more time.

The project was carried out in a reconfigurable automation cell using the AMRC’s Factory 2050 platform which allows robots, fixtures and machinery to be integrated and reconfigured easily, cutting set-up times and complexity.

The Robomag project is using robots to solve the problem of placing large permanent magnets on generator hubs

“What we have done is develop and de-risk an automated process that can replace Magnomatics’ current method for mounting permanent magnets onto its electrical machines,” Dr Winter reports. “This not only allows an increase in production rates, but also reduces the potential hazards to operators.”

“We are delighted with the outcome of this project,” says Magnomatics’ chief executive, Dave Latimer. “It is just one element of a series of developments all aimed at manufacturing large direct-drive generators for wind here in the UK. This project places Magnomatics on the right track to develop bigger generators and attract big offshore wind OEMs to Sheffield and the UK.”

The UK has more installed windpower capacity than any other country in the world and offshore wind already powers the equivalent of 4.5 million homes. The government has pledged to power every home with electricity from offshore wind by 2030 – a cornerstone of its plan for a green industrial revolution to encourage private investment and double jobs in the sector.

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