Winding Centre of Excellence

Bringing Industry & Network Partners together to grow the UK supply chain in eMachines & Drives

Welcome

The Winding Centre of Excellence has a full suite of winding equipment which are widely used in the automotive sector and focussed on development of volume processes and quality development. The facility will cover all types of windings, together with rotor assembly, magnetisation, impregnation and capability for electrical, thermal and mechanical testing along with magnetic characterisation of PM-rotors and lamination materials. This provides a unique, off-line facility to develop manufacturing processes for these higher volume applications.

The facility will provide:

OEMs and motor manufacturers with an offline process development facility for increased robustness, quality and consistency; and

UK supply chain companies of materials, coatings or laminations with the ability to trial new developments on mainstream automotive production equipment to demonstrate process robustness to provide confidence to the OEMs in UK capability.

Unique collaboration with leading WMG research groups, from state-of-the-art measurement capability in the metrology team, to laser welding process development with the laser applications group.

The facilities are fully operational and supports several existing DER (Driving the Electric Revolution), APC, and ATI projects within the UK supply chain providing the capability to development and enhance UK manufacturing capacity.

Key contact

wmgbusiness@warwick.ac.uk

Key links

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Winding Systems

Discrete Hairpin

Hairpin windings provide a very high copper slot fill factor in an eMachine resulting in higher power to weight ratio.

Our Wafios CNC Wire Forming System (FMU40E) to manufacture a variety of hairpin designs without the need to change tools as the basic tooling is independent hairpin geometry.

We’ve formed and have the ability to create hairpins of various materials (Copper, Aluminium) along with primary insulations, such as enamel, Kapton or extruded polymers, in addition to hollow conductors and litz wire.

The system includes all necessary tools for Hairpin manufacturing, also covering bus bars, phase leads, neutrals, star connections, and jumpers made of rectangular wire material. The system can also be used to form battery busbars and inductors.

Continuous Hairpin

Continuous hairpin winding designs offer a reduced overall axial length of the eMachine coupled with a reduction in the winding losses as the overhang of the windings from the stator lamination is reduced. When coupled with a reduction in the number of welds, as there are no open hairpin tails, the ability to manufacture continuous hairpins is essential for the DER Winding Centre of Excellence for trialling new technologies.
These design benefits compliment higher speed motor designs due to its potential to increase the numbers of conductors per slot and slot number – when compared to discrete hairpins designs.
The Aumann NWS/S needle winding system is an automated winding system capable of winding both

round (0.4mm to 3.5mm diameter) and

rectangular (1 x 5mm to 3 x 10mm cross-section) wires.

Including aluminium and materials with novel coatings.

The production line is capable of the roll-up, compression of the double-layer wound mat, insertion, and the expansion of the double-layer wound mat into the stator lamination stack.

Concentrated Winding

Concentrated windings provide a singular coil wound around a stator tooth or bobbin. This is a common method in the production of eMachine stators and the coils can be manufactured quickly. The result is a minimal coil overhang length from the stator lamination stack.
Therefore, it is natural that our NWS/S needle winding system has the capability to produce concentrated wound coils at a range of wire diameters.
Similar to all our other winding processes, it will be suitable for both copper and aluminium with novel insulation coatings.

Rotor Winding

Various rotor topologies are possible at the Winding Centre of Excellence, such as wound rotors.
The NWS needle winding system can directly wind the inside or outside of grooved rotors.
The various coil winding materials and coatings are suitable for this application with the addition of rotor mounting devices and basic holders.

Axil Coil Winding

In addition to conventional round and rectangular wires, newer coil winding technologies for novel motors are able to be trialled. Axial coil forming is possible on our Wafios CNC Spring and Wire Forming System.
Axial flux motors are becoming increasingly explored for automotive and aerospace applications due to their inherent higher torque and compact forms. The axial direction (rotational axis) of magnetic flux, rather than radially, results in a much shorter length of the rotor.

Distributed Winding

Distributed windings form the bulk of eMachines now manufactured. The Aumann NWS/S needle winding equipment is fitted with a manipular arm to allow automated winding of distributed coils with up to 24 wires in hand.
This will be able to provide bespoke distributed windings for prototypes or early phase production.

Welding

Remote Laser Welding

Remote Laser welding (RLW) for the joining of hairpins (both discrete and continuous) along with connection to busbars & terminals is a production solution for welding joints.
The Trumpf 6kW laser at the facility has image processing capability, to detect positioning of components to be welded, and beam formation technology to produce a low-spatter weld.
RLW systems are flexible for the joining of dissimilar materials, such as copper and aluminium, which allows for process development for sustainable copper-free eMachines with aluminium windings.
The welding system further compliments WMG capabilities in the Laser Welding Application Group

Impregnation

Trickle Impregnation

Following the winding and welding of the stator, impregnation is the next process flow in the manufacture of eMachines. Impregnation is a critical part of the creation of the stator as it provides the thermal pathway of heat from the windings to the laminations and cooling system. The impregnated stator has an improved mechanical structure to prevent vibrations of the windings in the lamination stack.
The trickle impregnation method is one of the most effective impregnation approaches, especially for high slot fill requirements and volume production cycle times. The stator is infrared heated while being rotated and impregnated with a controlled flow rate of resin.
Impregnation curing is completed in a convectional oven for best controlling the part temperature during curing.
The equipment at the Winding Centre of Excellence supports a wide range of impregnation resins and the dispensing of one or two-part resins with additional nozzles for a quick turnaround between trialling alternative resins. The equipment also provides adaptable fitting of stators of various sizes without the need for additional tooling costs.

Permanent Magnet Rotor Assembly

Magnet Insertion

The magnet insertion capability at the Winding Centre of Excellence is fundamental in the production of permanent magnet (PM) eMachines.
The magnet insertion stations at the facility allow for inserting either unmagnetized or magnetised magnets into a laminated rotor stack. A controlled and adjustable volume of adhesive can be applied to each of the slots before insertion.
The equipment is capable of utilising several types of PM materials, including NeFeB, SmCo, Alnico & Ferrites for trialling PM machines for high-temperature or more sustainable eMachine designs. This eMachine topology benefits from high-torque density and efficient operation common in the automotive sector.

Magnetisation

Correct magnetisation is a critical area that defines the performance of a permanent magnet (PM) eMachine. The system flexibility at the Winding Centre of Excellence allows for the magnetisation of individual PMs for insertion into rotor slots.
Operators do not need to handle magnetised magnets which translates to improved process development for high-volume production.
The magnetisation station can demagnetise individual magnetised magnets of any material.

Magnetic Characterisation

Rotor Characterisation - Validation of magnetised PM-rotors is essential to ensure the magnetic field of the rotor is as per design specification. The capability in the Winding Centre of Excellence allows for magnetic flux mapping and analysis of magnetised rotor assemblies to provide data on the manufactured part.
Helmholtz Coil - For process quality control of individual magnets, a Helmholtz Coil is used to measure the flux of individual magnets. This pre-assembly process validation ensures the level of magnetisation is as expected.