The market for electric motors is experiencing a step-growth due to their adoption across a range of industrial sectors. This increased demand also highlights the importance of end-of-life management of electric motors and a requirement for appropriate strategies for the high value materials embedded in them. This paper aims to offer a holistic view on the circular economy research for electric motors and the role of Industry 4.0 technologies by presenting the state-of-the-art available in literature and comparing it with the industrial perspective. The literature review revealed the absence of a methodology for selecting the best end-of-life scenario for industrial electric motors. Recycling, which is an end-of-product-life strategy, was found to be the key focus area of research. Reuse, which is a better strategy in terms of waste hierarchy, was the least researched area due to lack of information about the condition and availability of returned products. In order to capture the current landscape within the UK for the repair, remanufacture and recycling of electrical machines, a structured survey of UK based companies was conducted. The survey revealed that nearly half of the companies do not undertake any repair strategies for electrical machine components; however, there was an aspiration from the respondents to migrate their companies towards more sustainable activities. The industry survey and the review of existing literature led to the identification of research trends, challenges and recommendations for future research.

Permanent magnet (PM) electrical machines are an ever increasingly utilised motor topology for numerous industries such as automotive, aerospace, manufacturing, energy and premium consumer goods. PM electrical machines exhibit high power density, high operating efficiency and high torque to current ratio, whilst remaining robust and fault tolerant. However, the stator windings account for a significant proportion of the overall motor losses. There are many avenues for machine designers to potentially reduce winding losses whilst increasing overall efficiency and performance. Such avenues include, thermal management systems, novel winding materials and novel winding manufacturing methods. Additive manufacturing is generally recognised as a transformative manufacturing technology, especially in the design of electric machines. The ability to create a wide array of geometric shapes offers a level of design freedom that was previously unattainable. Additive manufacturing is therefore utilised in this paper to produce novel, optimised winding designs that have been configured to minimise total machine loss and maximise machine efficiency. This paper investigates the use of an algorithmic optimisation process within Ansys Optislang, and automated using python scripting. The optimisation process consists of sensitivity analysis utilising an efficient hybrid 2D FEA-Analytical model, meta-modelling and genetic algorithm to search the design space for optimal winding designs. The optimal designs are then validated against 2D and 3D FEA high precision motor models within Ansys maxwell and MotorCad and compared against a benchmark winding configuration. It was found that the most optimal winding design produced a motor efficiency of 97%.

Flow forming is a near-net shape forming process used to produce a range of tubular components. Advantages of the process include increased mechanical properties, grain refinement and high production rates. The cost effectiveness of the process stems from a reduction in input weight and a reduction in final machining time as compared to machine from solid routes. Careful selection of flow forming parameters, such as feed rate and spindle speed, is needed to ensure that the dimensional requirements of component design are met. The main purpose of this work was to explore the effects of machine parameters on geometrical outputs of flow formed trial parts in Cr-Mo-V steel, which is used in aerospace applications. Cr-Mo-V steel was flow formed in the annealed and the hardened and tempered conditions to assess the formability of the material across a range of input hardness. Results including inner diameter growth, formed wall thickness and material sectional hardness are presented. Forming trials were conducted at the Advanced Forming Research Centre on a WF STR600/3 flow former, which is equipped with force sensors on all three of the forming axes. The required forming loads are a significant aspect of managing tool life in an industrial setting, therefore the roller loads generated during forming have been studied. Experiments showed that there is a clear link between machine parameters and geometrical outputs. Slower feed rates and faster spindle speeds resulted in larger inner diameter growth and reduced wall thicknesses. Increased spindle speeds also caused a significant reduction in forming load. The hardness of the material was found to be proportional to the thickness reduction imposed on the trial parts in the annealed condition. Overall, it was observed that varying parameters in flow forming produced clear trends in the outputs, which can be used to predict tolerances in the design of components.

Electrification is increasing in prevalence due to the importance placed on it for achieving global net zero targets. This has led to the proliferation of electrical mobility, including the wide-scale production of passenger vehicles, personal mobility devices and recent announcements regarding electrically powered aircraft, as well as in energy production. Electrical machines provide a cleaner source of energy during operation in comparison to their traditional fossil-based alternatives. The uncertainty and lack of transparency hanging over these green credentials can be attributed to how these products are manufactured and then disposed of at the end of their life. For them to be a truly sustainable solution, improvements need to be made across their entire life cycle. With the projected increase in their numbers due to the advancement of electrification, this current life cycle is not sustainable, directly opposing the intention of these products. This paper will introduce the current demand and challenges. It will also present these motors broken down into their constituent parts and follow each through their typical lifecycle. This paper presents the typical current life cycle of permanent magnet electrical machines, demonstrating the environmental issues associated with the current linear life cycle, and proposing alternative practices, to ease the environmental burden.

Permanent magnet synchronous machines (PMSM) are an increasingly popular motor topology for many industries such as automotive, aerospace, manufacturing, energy and premium consumer goods. PMSM offer many advantages compared to other topologies such as induction machines due to their higher power density, greater operational efficiency and high torque, whilst remaining robust and fault tolerant. One specific area of interest is the stator windings. With increasing operational speed, the geometric configuration of the winding becomes ever increasingly important in order to mitigate increasing AC losses. The windings conductor lay in slot, position, shape and orientation become critical in combating loss mechanisms such as skin effect, proximity effect and armature reaction. Additive manufacturing offers a novel geometric design freedom that has previously been unattainable using traditional manufacturing methods and enables the ability to create highly novel winding design methodologies that could potentially revolutionise winding design and performance. This work investigates the losses observed from an algorithmically designed stator winding, additively manufactured in Al10SiMg using the laser powder bed fusion process. A motorette sub-assembly was constructed and the DC and AC power losses were measured and compared against a theoretical 3D FEA based simulation model. The outcome observed a 9.4% difference in losses comparing theoretical and measured winding values utilising the RAC/RDC measured. Samples of the additively manufactured conductor parts have been tested for resistivity and conductivity.

It is common practice for electrical machines to be designed with a focus predominantly on the electromagnetic performance. The mechanical design is then subsequently undertaken to meet various mechanical performance criteria, with this finalised design then passed on for manufacture. In many cases, the manufacturing constraints have not been taken fully into consideration during the electromagnetic or more particularly the mechanical design and hence some changes are required to the design to make it manufacturable. This in turn can lead to a non-optimal machine being manufactured. If manufacturing constraints and opportunities are regarded as key quantitative inputs to the design process, not only can these post-design changes be minimised, but benefits of the manufacturing process can be exploited to produce a superior product. This paper proposes a methodology to fully integrate the mechanical design and manufacturing process routes into electrical machine design and illustrates its utility within the context of light-weighting of a permanent magnet rotor for an aerospace electrical machine. Within the proposed methodology, several alternative configurations of the rotor are considered with applicable manufacturing routes identified at the initial stages of design and an analytical design procedure to fulfil the application and performance criteria is developed. Different manufacturing materials and constraints as well as the impact of manufacturing process are identified to be embedded into the design procedures. Finally, the paper demonstrates an application of this methodology together with a discussion of the features which offer promise in achieving economically lighter weight design through integration of manufacturing into the design procedure.