Research projects:
Grand Challenge 2.3

Manufacturing technologies for flexibility and customisation

Led By AMRC

Grand challenges 2.3 focuses on developing more flexible manufacturing processes and the opportunities in machine design which this opens. Two key areas of research are remote laser cutting of electrical steels, and robotic winding. 

Remote laser cutting 

Remote laser cutting (RLC) is proposed as an alternative to conventional laser cutting used for of laminations. RLC relies on the use of high-brilliance lasers to achieve power densities 10 7 – 10 10 W/cm 2 and high-speed scanning optics to achieve surface speeds on the order of several meters per second whereupon material partially vaporised. This vaporised fraction ejects the molten material from kerf, progressively cutting through the sheet over multiple scans. 

Research this year has continued to investigate the scale up of this process, producing the first complete stator by this method (see left) - the results of which were presented at E|DPC 2023 and published in conference proceedings2 . Research has also continued to investigate the influence of cutting parameters on cut edge and magnetic performance. Whilst these investigations have shown RLC to be highly productive and allow more complex features to be realised without compromising process times, investigations have yet to replicate the lower impact on magnetic performance reported in literature. Additionally scans of the top surface shows greater variation in burr and surface roughness in the kerf than previously observed in cross-sections. Research is planned to address burr condition by a clean-up laser scan in the second phase of the Hub.

Preparations are currently being made for an upgrade the existing continuous wave laser module to pulsed laser which will significantly extend the process parameter space into more ablative regime with the hope of avoiding thermal damage. It is anticipated that this laser will be around 2 kW emitting pulses of tens of nanoseconds in the near infra-red range. In parallel to this activity, researchers at the AMRC and University of Sheffield are also collaborating with researchers The Manufacturing Technology Centre (MTC) to investigate the influence of waterjet guided laser cutting on magnetic performance. A conference paper is currently being prepared for 13th CIRP Conference on Photonic Technologies. 

Robotic needle winding 

Industrial robot manipulators can be adapted to a wide range of tasks applicable to electrical machines and have been demonstrated in magnet placement, coils insertion and lamination stacking. Such robots are therefore proposed as the basis of a flexible manufacturing system that can switch between these various tasks, affording the benefits of automation, such as improved quality and throughput, without the inherent inflexibility of dedicated automation. Here work has continued to develop the use of industrial robots as the basis of a flexible needle winding system which can accommodate a wide range of winding designs. The results of this research were presented at E|DPC 2023 and published in the conference proceedings.  This reported on the suitability of industrial robots for needle winding with experimental trials on accuracy, repeatability and stiffness. The work also characterised the angular dependence of the wire leaving the needle on the wire tension under static conditions. A model has been created to estimate fluctuations in wire tension during needle winding due to Alicona scan of remote laser cut electrical steel showing burr condition and waviness in kerf.machining and subtractive machining. L. Tinkler et al, Manufacturing processes for 2.5D laminated stacks, 2023 13th International Electric Drives Production Conference (EDPC) Robotic need winding led by Gianmarco Pisanelli Page 42 this angular effect. Experimental trials are currently underway to measure these fluctuations by mounting the bobbin on a multi-axis load cell which will allow direct measurement of the magnitude and direction of the force imparted byd the wire. Thereafter research will focus on minimising these fluctuations by compensating through speed and tension control. In phase II of the FEMM Hub the robotic winding cell will refocus on other electrical machines assembly task as well as investigating the disassembly through aligned research projects. 

Flexible manufacturing technologies 

As report in the 2023 annual report, a desktop study was conducted into manufacturing processes for slinky stators. This is a technology highlighted on the Advanced Propulsion Centre’s Electrical Machines Roadmap to help improve material utilisation. This work estimated the material utilisation for different stator split ratios and observed a marginal benefit if the rotor lamination is also required. Several cutting processes were proposed and evaluated in terms of productivity and flexibility. The results of this work were presented as a poster at PEMD 2023 but were not published in proceedings to ensure open access to the work. A follow-up paper, bolstered with experimental results, is planned for 2024. 

In the past year Hub researcher Dr Alexei Winter has lead projects funded through the High-Value Manufacturing Catapult well aligned with the FEMM Hub to develop coil winding processes included wet winding of complete coil chains to avoid need for global impregnation after winding, and to demonstrate winding process for hollow conductors developed by the hub