Specialists in die-cast copper rotors for high efficiency

16/09/2015 16
By Nuno Fernando

François Dovergne, Responsible for the Rotors Division at FAVI S.A., explains the company’s experience of manufacturing copper rotors and the new market opportunities.


Can you briefly introduce FAVI?

Established in 1957, FAVI is a worldwide leader in copper and brass high-pressure die-casting of custom components. In addition, we build and maintain all tooling, optimize part design, and machine and assemble complete systems per customer specifications. The company is based in Hallencourt, northern France, and employs around 400 people.

What products do you make?

Around 80% of our activities are focused on shift fork assemblies for manual transmissions for cars. We are a Tier One supplier to most of the major European car manufacturers.

In 1995 we began to consider manufacturing copper rotors, based on our experience of high temperature casting. Over the next seven years we set up all aspects of the process to be able to cast copper rotors in serial production conditions. We started up this serial manufacture in 2002 and since then have produced more than 1.5 million die-cast copper rotors for asynchronous motors, a major innovation for increasing energy efficiency of industrial and electric car motors.

What sizes of copper rotors do you manufacture?

FAVI has the capacity to produce die-cast copper rotors in small, medium and large volumes. We make rotors for asynchronous machines of sizes from 20 to 360 mm, from a few watts to 115 kW. These include rotors for specific applications such as pumps, circulators, gearbox motors, forklift trucks, spindle motors, etc., as well as die-cast copper alloys such as CuSi for high torque requirements.

What is the state of the market for copper rotors?

Currently it’s rather flat. A few years ago when the new energy efficiency directive came into force we were anticipating a growth in the market for IE3 efficiency motors and hence more orders for copper rotors. However, most of the major industrial motor manufacturers have worked hard to improve the performance of aluminium rotors by, for example, using different kinds of laminations, or improving stator windings or rotor designs. They have done this to maximize their investments in their own aluminium casting facilities. So they have been able to reach the IE3 efficiency level without moving to copper rotors.

Will this situation change as efficiency levels increase still further?

Yes, we believe so. IE4 is a major step forward in motor efficiency which is more difficult to achieve using aluminium rotors. I think solutions will be found for some sizes by using aluminium rotors, but other sizes will have to go to copper.

What about new market opportunities?

We see the market for copper rotors moving from industrial motors to automotive applications. Most of the projects and prototypes we are running are in the field of electric mobility. In addition, we see great potential for high power induction motors. When you run an induction motor with a copper rotor to very high rotating speeds you can get a very good output of the motor, so very good power density, close to the performance of a permanent magnet with a synchronous motor.

Nearly all car manufacturers and OEMs have projects based around induction motors with copper rotors. So there is great potential and naturally we hope that some of these companies will come to FAVI for their copper rotors.

In this field we see a particularly strong opportunity for growth in hybrid vehicles. Our advantage as an automotive supplier for 30 years is that we are in close contact with the automotive industry and are used to working closely with them.

Is FAVI involved in designing motors too?

No, we work with automotive manufacturers more as a co-engineering partner. We advise on the process of die-casting, but our strength is not in motor design and optimization.

What are the main challenges you face?

For automotive applications the main challenge is mechanical behavior of the copper for high-speed motors. We are working on this and are making good progress.

New applications also bring new customer expectations and new challenges. But we have a strong R&D department who are constantly working on new materials to optimize our solutions.

We are also running some studies with technical universities. These include projects to improve the efficiency of rotors, and others related to metallurgy. The work we are doing with the automotive industry is also interesting for other applications using high-speed motors, such as spindle motors for milling machines. Copper rotors offer advantages for these applications too.

Such as …?

If you are looking for more power from a motor, aluminium gets too hot too quickly, leading to overheating of the motor. For the same size of motor, a copper rotor allows you to get more power out of the motor without a significant rise in temperature. A copper rotor also leads to space saving, which is a key factor in integrated motors when the available space is often limited but you still need to increase efficiency and/or power. In such applications a copper rotor allows you to improve the performance of the motor by keeping the same volume.

Is the higher price of copper a stumbling block?

If you just compare the price of an aluminium rotor with an equivalent copper rotor, then the higher price of copper is a deterrent. But if you look at total system costs and lifecycle costs then copper comes out more favorably. So there is still some education we have to do here, particularly with our industrial customers.

What is interesting is that an induction motor with a copper rotor is playing in the same field as a synchronous motor with a permanent magnet. The cost of copper then becomes less of an issue, because the copper will in most cases be less expensive than the permanent magnet.

And without the sourcing problems too, presumably?

Exactly! The sourcing of rare earth materials for permanent magnets is extremely insecure, whereas there is a plentiful supply of copper and it’s available at a worldwide market price. Buying copper is not an issue. We have two major suppliers and don’t have any sourcing issues.

Do you have much competition?

There are more companies producing copper rotors now than 10 or 20 years ago. This is good for the automotive industry and for us. The automotive industry needs a supply chain with technical solutions that are reliable, which is possible if there are several potential suppliers on the market. A major OEM will not launch a new product if there is only one potential supplier on the market.

For us, a bit of competition is good. It’s a challenge we are happy to rise to.


For more information on the FAVI copper portfolio, visit http://www.favi.com