Continuing just-auto’s interviews with the world’s largest wheel manufacturers, Matthew Beecham talked with David Yates, Commercial Manager, Europe, Alcoa Wheel Products – Forged Speciality Wheels about wheels for electric vehicles as well as trends in the use of finishes, materials and styling.
just-auto: I’d like to start by asking how your wheels business is shaping-up, the key events over the 12 months, perhaps elaborating on some successful projects?
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David Yates: Car production volumes have contracted significantly in the last two years, resulting in excess wheel manufacturing capacity in Europe. However, this year the markets seem to be faring much better and car production volumes are recovering. In Alcoa 2010 has been an exciting year with plenty of new programme launches in both Europe and the US in various types of vehicle. For example, we have enjoyed success with numerous OEMs producing high performance cars; we recently announced the launch of forged wheel programmes on Ferrari 458 Italia and Aston Martin Rapide, amongst others. Additionally, Alcoa is using the aggressive design and engineering, development and production know-how so desired by the performance brands like Ferrari, to the benefit of alternative vehicle platforms. Alcoa has recently launched a very lightweight, high-volume 17” forged wheel for the Chevy Volt.
Interest in electric vehicles is gaining momentum. Could you talk us through the ways you are developing wheels for such vehicles?
The importance of EVs is increasing and so too is the need for lighter weight materials and improved aerodynamics to improve vehicle range. This applies to the wheels, too. The benefits of changing to forged wheels are huge. Forged wheels can be 20 – 30% lighter than cast wheels and every 45kg of vehicle weight savings generates an increase of 1.5 – 2% in fuel economy. In the US, Toyota’s hybrid Prius uses 15-inch cast aluminium wheels that weigh 8.6kg each. Our new wheels for the Chevy Volt are 17-inches, and thus much larger but are significantly lighter; the lighter weight having a positive impact on the battery range of the car. Additionally, with more aggressive styling we can go even lighter.
Although low weight on that programme was critical, an aerodynamic design was also hugely important. We went through 10 to 12 design iterations to get the finished wheel. And if you look at it closely, it has lightener pockets on the front and is very flat; internally we call it a hammer-style spoke. This design creates less wind shear, so it adds to General Motors’ claim that they will get a 64km range from one charge.
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By GlobalDataAlcoa is very progressive and we are always investigating ways to further improve, including the materials we use. At the moment, 6061-grade aluminium is used for our wheels but in the future we may offer additional options to provide our customers with even lighter wheels. Being a part of Alcoa Corporation, we potentially have access to different grades of aluminium, including aerospace alloys, and we have 350 engineers working on further improving them, meaning we can offer our customers more options. Should we introduce a different grade of aluminium, the weight of the wheels on vehicles could be reduced even further.
What do you see as the main trends in wheel design? Is it simply bigger, lighter and brighter wheels?
Bigger and lighter are certainly key trends that have been evident for some time, and will continue to be important. OEMs are constantly seeking ways to further improve the performance of their cars. This means lighter weight, lower CO2 emissions and reduced fuel consumption. However, for conventional cars the consumer does not want to compromise on performance and driving dynamics. Alternative fuelled vehicles are increasingly important, but at this stage do not represent the mass of vehicle production and reducing weight in those conventional cars is a tough challenge. Forged wheels offer an easy and quick fix to weight reduction. Alcoa’s design and engineering experience coupled with our processes and technologies can produce forged wheels that save significant amounts of weight compared to comparable cast wheels, helping car manufacturers’ move towards their weight reduction targets.
I guess wheel diameters are increasing too with low profile tyres. From a technical standpoint, what are the challenges to that?
This is often more of a problem for cast wheel technologies as our comparable forged wheels are stronger. Alcoa’s forging processes create a tightly aligned grain structure of the metal in a wheel, resulting in a stronger structure than the random grain structure of a cast wheel. Therefore in impact tests our forged wheels would, generally, easily outperform a conventional cast wheel. In the real world this means that pot holes and other road imperfections can have a very damaging effect on cast wheels if you hit them at speed, resulting in cracks, deflated tyres or worse. Alcoa’s forged wheels are less likely to be damaged in those circumstances, making them an important product for improving the safety of the driver.
While wheel size may matter most in terms of design, style must rank a close second. What are you seeing there in terms of wheel styling?
Weight is a critical issue as it is an increasingly important focus for car manufacturers. But then designers sketch a concept vehicle with oversized wheels at the corners that emphasize the overall style of the vehicle but many of these concepts aren’t practical and don’t reach series production. Large wheel size and thinner spoke design trends are having a knock-on effect on wheel styles as some OEMs try to move towards lighter weight styles. Additionally, aerodynamic styling is increasing important as OEMs look to improve fuel consumption.
Are there any hard and fast trends emerging with regard to, say, finishes?
There have been some niche applications launched this year with very different finishes. They look great but are unlikely at this stage to reach mass production. The mass volume market remains fairly consistent, generally requiring silver paint with clear coat. However, for the high performance cars there have been alternative colours used, often with a bright machine finish. This can have a very strong visual impact on the right car. In addition, machining changes can alter the appearance of the wheel, while utilising the same basic wheel design and tooling, allowing OEMs to differentiate their wheel choices from year to year without having to start from scratch with a new wheel programme. This is another significant benefit Alcoa offers compared to its cast wheel competitors. Creating forged wheels from blanks allows Alcoa to launch programmes very quickly, whilst retaining the mechanical properties and strong fatigue performance of forged feature wheels.
Turning to trends in the use of material to produce wheels. I guess we are unlikely to see the total eclipse of alloy over steel for a number of reasons, not least steel’s relative low cost of alloy?
Steel still has a presence in the major auto markets and more of a presence in the emerging markets, largely resulting from the lower cost compared to aluminium wheels. However, in the more developed markets the preferred material is aluminium which dwarfs the volumes for steel in wheel applications. In our view, aluminium will remain the dominant material going forward as it is the only material available now that can offer the weight and styling benefits the consumer wants in a mass production environment. Within aluminium, the choice then becomes cast versus forged. As wheels get larger and the need for weight loss increases, the competitiveness of cast wheels reduces. Cast aluminium wheel designs can be compromising by their heavy weight, which is, in turn, increasing demand in Europe for forged wheels.
What’s blue sky in terms of research and development into wheels these days? How much further can wheel design go?
Car makers strive for lighter weight and the cars of the future will be light and very efficient. Wheels are critical to achieving this as, generally, every car has four wheels that all have the same weight, so if we can save 4kg on one wheel we achieve 16kg saved on the car. Alcoa has 120 years of aluminium innovation that we can access and offer to our customers. Resources like the Alcoa Technical Center, the largest light metals research and development facility in the world, allow us to push the envelope on new innovations, technologies and processes. Design is an important factor in achieving light wheel styles and an area of focus for Alcoa, so too is manufacturing technologies and techniques. If you apply all of these factors to our forged wheels the result is very light, very strong wheels that reduce CO2 emissions and fuel consumption, improve driving dynamics and, just as importantly, look fantastic.
