WMG Winding Centre of Excellence validates key stator impregnation processes, advancing Safran’s ENGINeUS electrical machine development.

The aviation industry is undergoing a significant shift towards electric and hybrid propulsion technologies, including electric Vertical Take-off and Landing (eVTOL), electric Short Take-Off and Landing (eSTOL), and electric Conventional Take-Off and Landing (eCTOL). As this transition accelerates, these technologies are reshaping air travel from urban mobility to regional connectivity offering cleaner, quieter and more efficient flight.

Central to this transformation are advanced electrical machines, power electronics, and controls, which are crucial for the performance and reliability of next-generation propulsion systems. Safran Electrical and Power (SEP) is at the forefront of this shift with its ENGINeUS electric propulsion engines for eVTOL, eSTOL, and eCTOL platforms, as well as electrical machines for hybrid aircraft.

Unlike conventional aircraft, emerging eVTOL and eCTOL markets demand significantly higher production volumes of electrical machines, challenging traditional manufacturing methods. Automation, inspection and digitalisation offer promising solutions. A key challenge is scaling production to meet the demands of these new markets, which will require for more aircraft than conventional aviation.

Safran’s UK site in Pitstone is developing an Industry 4.0 pilot production line for electrical machine manufacturing. One critical aspect of this process is stator impregnation, which insulates and strengthens electrical machines to meet aerospace-grade performance standards. This involves reinforcing and insulating the windings with resin. While essential, traditional methods are time-consuming and difficult to automate, creating a bottleneck in scalable production.

As part of the £14.9M Aerospace Manufacturing Capability (AeroMC) project, (funded by the Aerospace Technology Institute (ATI) programme through Innovate UK), WMG contributed its advanced manufacturing expertise and state-of-the-art facilities at the Winding Centre of Excellence (WCE) to support SEP in developing scalable, high-performance electrical machines. WMG leveraged its specialised equipment and knowledge to support SEP overcome key manufacturing challenges.

To address this challenge, WMG and Safran collaborated to explore and validate alternative impregnation processes laying the foundation for scalable, automated production of next-generation electric propulsion systems. This collaboration led to a focused investigation into one of the most critical steps in electrical machine manufacturing: the impregnation process.

Challenge

SEP faced the challenge of identifying a streamlined impregnation process for its diverse stator range, aiming to reduce lead times and enable automation. It was also crucial to maintain high quality outcomes, with a minimum fill factor required to meet aerospace standards.

SEP aimed to increase the TRL and MRL from 4 to 6 to meet their requirements for realising an automated pilot line for electrical machines, enabling production volumes of up to 5,000 units per annum.

Solution

WMG was awarded £4 million from the ‘Driving the Electric Revolution’ programme and the High Value Manufacturing Catapult (HVMC) to develop the WCE, supporting UK supply chain in manufacturing electrical machines by providing access to specialist equipment.

WMG’s applied its trickle impregnation expertise and equipment to impregnate the ENGINeUS stator, analysing the processes’ suitability compared to current industrial practices. High resin fill across the stator slots was achieved, demonstrating process control and resin flow characteristics. While not the primary objective, it was successfully validated that trickle impregnation would not satisfy the required impregnation quality. However, the controlled resin flow process showed potential for waste reduction in a pilot line framework.

WMG was able to achieve excellent impregnation fill factor, increasing confidence in the process. While this process did not satisfy SEP’s specific requirements, it provided valuable insights, and critical learnings, showcasing the WCE role as a pioneering step in the advancement of the electric aviation advancement.

“We are really pleased that WMG has been able to support SEP in developing a stator impregnation technique aligned with automated manufacture requirements. The equipment and capabilities at the Winding Centre of Excellence enabled the WMG team to explore and evaluate candidate impregnation processes. Through this collaboration, WMG team gained critical hands-on experience in this key technology area, further strengthening its role in advancing electrical machine manufacturing.”

- Dr Sul Ademi, Lead Engineer for Electrical Machines

Impact

The successful demonstration of WMG’s trickle impregnation process helped SEP in further defining their impregnation requirements and provided valuable insights into the limitations of trickle impregnation for aviation grade applications.

Key outcomes include:

Process Understanding Improvement: Provided deeper insights into trickle impregnation processes, particularly resin behaviour, flow characteristics and fill limitations supporting SEP’s in refining their impregnation specifications.
Resource Optimisation: Reduced resin consumption and minimised waste, aligning with sustainability goals.
Scalability for Automation: Developed a process framework compatible with automated manufacturing lines, supporting future scalability.

The collaboration also provided valuable hands-on experience for WMG's early-career engineers fostering skill development and knowledge transfer within the team.

“The ENGINeUS family of air-cooled engines is a key enabler to the future sustainability of aviation, and performance and reliability are fundamental to future applications. The work performed on the AeroMC pilot line is demonstrating how crucial new technologies such as automated trickle impregnation can be integrated within an innovative production system to achieve the optimal, repeatable, series manufacturing of these highly reliable engines for the future.”

- Giovanni Raimondi, Machines & Drive Systems Technical Director, Safran Electrical & Power

Get in touch to find out how WMG can help you with a challenge that can improve technology for good at wmgbusiness@warwick.ac.ukLink opens in a new window