Wednesday, July 24, 2024

Electrical erosion resistant bearings for EVs

Electrical erosion resistant bearings for EVs

Following the completion of performance evaluations, NSK can now offer a broader
range of anti-electrical-erosion technologies for eAxle bearings
used on electric
vehicles (EVs).
Among the new options are over-moulded bearings and conductive
brushes, elevating NSK’s ability to meet diverse demands from automotive OEMs as
they look to combat electrical erosion and, in turn, improve reliability and extend EV

Electrical erosion resistant bearings for EVs
Example of an NSK plastic over-moulded bearing. Photo: NSK

With growing awareness of the world’s urgent climate-change agenda, society and industry
are accelerating their journey towards carbon neutrality. The rising demand for EVs means
there is a real opportunity to enhance the sustainability of the transport sector, but the
success of this endeavour depends heavily on the underlying technologies. For instance, a
key issue in ensuring the long operational life of EVs is preventing the electrical erosion of
critical eAxle components such as bearings.
Preventing electrical erosion is becoming increasingly difficult due to the higher output of electric motors and higher drive voltages. Here, technologies like insulating ceramic-ball bearings (hybrid bearings) are most effective way of providing electrical insulation, but are not always the optimal solution for high-volume applications such as EVs.
A good alternative is the adoption of plastic over-moulded bearings, which deliver the electrical insulation required for eAxles but at a lower cost than ceramic-ball bearings.
Notably, NSK configures its over-moulded bearings to suit the application and any specific
requirements. The materials and manufacturing processes would be quite different for an
eAxle and those of a railway application, for example.
Another option to resist electrical erosion is the use of conductive brushes. However, trends in eAxle motors are moving towards the use of highly efficient oil-cooled systems, for which conventional conductive brushes are not suitable, especially in combination with high speeds. NSK’s new brushes differ in that they offer sufficient conductivity for a wide range of eAxle applications, even those involving cooling oil lubricated environments. As a further benefit, it is possible to incorporate the conductive brush directly into the shaft to save space.
NSK has already completed basic durability evaluations and can now provide customers
with proposals for its latest anti-electrical-erosion technologies, including evaluation data,
for practical applications.

Nsk’s anti-electrical-erosion options

In summary, the company’s anti-electrical-erosion options cover both insulating and
conductive methods to meet a diverse range of design requirements
that balance
application and volume criteria. These technologies improve reliability and include measures that support the reduction of overall eAxle unit size. They also contribute to lower electricity consumption and longer vehicle range on a single charge.

Mecflon to avoid noise and reduce friction an losses

Compared to Ptfe, Meflon is formulated to provide increased efficiency, improved wear resistance, and decreased starting torque in demanding applications of food, spa, and drinkable water segments .

25During the last ten years, the market has requested sometimes to increase the operational flexibility of cooling systems using auxiliary pumps for a better control of engine cooling and efficiency, in order to meet more stringent regulations in terms of CO2 emissions. In many cases the auxiliary pumps are driven by brushless motor, regretfully still with some limited performances in terms of pump efficiency and vibrations/noise failures,  as it has been for dishwasher application of this type of motor.
Meccanotecnica Umbra developed a material for sliding parts such as bushings to reduce the sliding friction: the solution had been the MTU Ptfe material with appropriate fillers, Mecflon.
MecflonMeflon, when compared to other grades of Ptfe, is formulated to provide increased efficiency, improved wear resistance, and decreased starting torque in demanding applications of food, spa, and drinkable water segments.  As it was for the mechanical seal of dishwasher pumps,  MTU analyzed the possibility of supplying in particular bushings and rings, made with same innovative materials to prevent sticking and noise, to Tier1s and OEs that are partially replacing the traditional pumps (equipped with mechanical seals).
The irregularities of performances in real conditions are related to the occurrence of irregular flow situations and for mechanical seal, this phenomenon is bigger, because the lubricating film between the faces is typically very small. Therefore, the effect of Mecflon also for bushings has been again the key factor for avoiding sticking and noise, as it had been for traditional low power electric pumps, provided with mechanical seals.
In  the past two years   MTU  has got relevant progress in the definition of the project for brushless motors and has overtaken the preliminary testing activity on prototypes, with sizeable advantage also in terms of wear, and not only sticking and noise, in comparison with standard materials used for mass production.
Pumps equipped with Ptfe bushings don’t present axial wear of the front flange of the bushing and show lower wear of radial surface.
However, the combined radial wear of bushings and shaft for Mecflon Y4 solutions makes significantly lower overall damage in terms of eccentricity.
Morerecently MTU has started a specific development program for application of PTFE bushing to cooling system water pump , taking into account the typical working conditions of the automotive segment (-40/140 ° C, up to 6000 rpm, high additivated coolant, continuous operation during in-house recharge of batteries of hybrid or electric vehicles).

Electric Motors Efficiency needs better copper

A new manufacturing process yields highest conductivity copper composites at bulk scale. This is a discovery of researchers at Pacific Northwest National Laboratory (PNNL): they have increased the conductivity of copper wire by about five percent. Higher conductivity means that less copper is needed for the same efficiency, which can reduce the weight and volume of various components that are expected to power our future electric vehicles.

The laboratory teamed with General Motors to test out the souped-up copper wire for use in vehicle motor components. As part of a cost-shared research project, the team validated the increased conductivity and found that it also has higher ductility-the ability to stretch farther before it breaks. In other physical properties, it behaved just like regular copper so it can be welded and subjected to other mechanical stresses with no degradation of performance. This means that no specialized manufacturing methods are necessary to assemble motors-only the new advanced PNNL copper composite.

The technology can apply to any industry that uses copper to move electrical energy, including power transmission, electronics, wireless chargers, electric motors, generators, under-sea cables, and batteries.

General Motors Research and Development engineers verified the higher conductivity copper wire can be welded, brazed, and formed in exactly the same way as conventional copper wire. This indicates seamless integration with existing motor manufacturing processes.

«To further lightweight motors, advances in materials is the new paradigm – said Darrell Herling of PNNL’s Energy Processes and Materials Division. Higher conductivity copper could be a disruptive approach to lightweighting and/or increasing efficiency for any electric motor or wireless vehicle charging sytem».

Aluminium windings?

Copper, material typically used for the windings of conventional electric motors, is more expensive and heavier than aluminium. For this reason as well, they have started the first experimentations of aluminium windings for electric motors, expected to replace a fundamental role, that is to say generating the electromagnetic field for the rotor.
Concerning this, protagonist is the British company Ricardo, which has started developing electric motors with aluminium windings intended for small-size electric cars.
Ricardo has been developing a rare-earth magnet-free sustainable electric motor concept with aluminium stator windings, which retains the key attributes of magnet-rich motors. The goal has been to create technology which is robust, costs less than current products and reduces lifecycle impact by eliminating the use of scarce resources for example up to 12kg of rare earth metals and also high acidification materials such as copper without impacting motor function or quality.
Therefore, aluminium is no longer used just for the bars of induction motors thanks to UK-Alumotor, led by Ricardo with Aspire Engineering, Brandauer, Warwick Manufacturing Group at The University of Warwick, Phoenix Scientific Industries, and Global Technologies Racing, is a consortium of experts formed to develop a supply chain around an innovative proprietary design for an electric motor.
The consortium’s aim is to grow UK manufacturing capability and to develop the next generation of skilled engineers and technicians.
UK-Alumotor consortium has received an award from Driving Electric Revolution Challenge fund – through UK Research and Innovation – to establish a UK supply chain for electric machines: leveraging manufacturing expertise to deliver next generation sustainable electric motors.

Self-lubricating polymer bearings


In many applications, bearings and supports must work also in presence of filth, dust and chips. For this reason, they need continuous lubrication and maintenance interventions. Polymer bearings by igus are lubrication- and maintenance-free, even if the support is made of metal. Precisely for these systems with metal supports, igus has developed new iglidur J high-performance plastic bearings.
The new self-lubricating bearings with sheet metal housing allow notably decreasing maintenance costs. Moreover, this new material prevents the deposition of dirtiness and dust and this represents a considerable advantage in terms of wear and allows avoiding unforeseen machine downtimes. Igubal bearings are made through injection moulding and they are economically advantageous.
They can be mounted in few seconds to replace ball bearings in already existing standard metal housings or they can be bought with a low-cost sheet metal support. The joint is composed by the sheet metal housing and by igubal ball bearing and is directly available in stock. The plastic bearing has high resistance to wear and features a very low friction coefficient in dry operation.
Currently, igubal bearings are available in three sizes for low-cost sheet metal housings (Ø20, 25 and 30 mm) and for injection moulded housings (UC204-210).

Axalta A new epoxy resin Voltacast 3310

Axalta, a global supplier of liquid and powder coatings, launches Voltacast 3310/Voltacast H134, a new epoxy-based casting resin system that expands the Voltacast product portfolio of casting resins from Axalta’s Energy Solutions business.

Voltacast 3310 is specifically designed to offer high thermal stability in combination with high thermal conductivity for winding head encapsulation or total stator encapsulation of electric motors, like servo drives or large machine tools.

“We are always looking to expand our product portfolios and to meet the ever-evolving needs of our customers,” explains Christoph Lomoschitz, Global Product Manager for Axalta’s Energy Solutions business. “Voltacast 3310 ensures outstanding resistance to a variety of automatic transmission fluid oils used in electric vehicles, and its high thermal conductivity in combination with oil cooling of electric motors allows maximum heat dissipation.”

Voltacast 3310/Voltacast H134’s anhydride-free system can be cured at room temperature or preferably at temperatures up to 70ºC. The cured material is flame retardant, fulfilling the requirements of Underwriters Laboratories (UL) standard 94, class V0, and will shortly receive official UL recognition.
The new Voltacast 3300 range is comprised of two-component systems – an epoxy resin and a hardener. The products of the Voltacast 3300 range offer superior thermal conductivity, from 1.2 W/mK up to 1.6 W/mK, without compromising an easy and safe application, as the processing viscosities are only 2200 mPa*s to 2400mPa*s at room temperature. The new Voltacast materials are very versatile, with glass transition temperatures of 24ºC, 60ºC and 95ºC, depending on the final application requirements.

Investment for a low environmental impact battery plant in Poland

Global top player in sustainable technologies Johnson Matthey (JM), announced that its new battery materials facility in Konin, Poland, has received a combined €135 million investment from two leading development banks, in yet another boost for the commercialisation of eLNO and the electric car industry. eLNO is the portfolio of ultra-high energy density next generation cathode battery materials. These are expected to improve the performance of lithium ion batteries and help promote electric vehicle usage on a larger scale.
The production capacity in Konin will be 10,000 tonnes of eLNO per year, enough for around 100,000 fully electric vehicles. In addition, the site, which will start production in 2022, has the potential to expand tenfold through further investment. Construction of the plant began this year.
Johnson Matthey aims to create a low environmental impact battery supply chain, using renewable energy and sourcing raw materials – lithium, cobalt, nickel – from “ethical” mines.
«Construction of the new plant in Konin – said Christian Günther, Chief Executive, Battery Materials at Johnson Matthey – is a significant milestone in the commercialisation of our eLNO battery cathode materials. Supported by this funding, we plan to have eLNO in production on auto platforms by 2024, enabling the shift to electric vehicles and a cleaner, healthier world for us all».

Impregnating resins for mechanical stability and insulation

Axalta’s bespoke automotive products provide electrical insulation solutions and are designed to improve the performance levels of modern electric motors. They include Voltron wire enamel, Voltatex 4200 for impregnation, and adhesive electrical steel coatings such as Voltatex 1175W and Voltatex 1075K. Axalta has been a global supplier in the manufacture of high-quality, high-performance liquid insulating systems and materials for over 70 years and it supplies its Energy Solutions range of Impregnating Resins, which provide mechanical stability and insulation for electrical motors in full electric as well as hybrid vehicles, to nearly all well-known light vehicle OEMs. Michael Glomp, Vice President of Axalta’s global Energy Solutions business, says, “The development of efficient, high-performance and reliable engines for hybrid and electric vehicles continually presents new requirements and challenges for electrical insulation materials.”

Mega-deposit of rare earths discovered in Sweden: turning point for the EU?

Besides an iron ore mine, the Swedish State mining company LKAB has discovered a deposit of over 1 million tons of rare earths in the northern area of Kiruna, in Lapland. As we know, they are strategic minerals for the production of electric vehicles, wind turbines, chips and hi-tech products. However, until now they are not extracted in Europe, but most of them come from China. Therefore, might this discovery free Europe from this existing dependence on China?
Jan Mostrom, CEO of LKAB explained: «The important thing is that we can identify quite big deposits of this material here inside the European Union, because these materials will be vital for electrification. The deposit is “enormous” and represents a first step towards Europe’s self-sufficiency ».