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Extrusions' key roles in the automotive sector


While they may place the factors influencing a decision in different orders of importance, vehicle purchasers have price, performance, practicality, size, reliability, appearance and brand in mind when making a choice. Range between refilling, or recharging, is another consideration that has risen in importance for corporate and private buyers alike, whether in terms of running costs or – in addition for electric vehicles in particular – distance between charging points.

The degree to which buyers think about the materials used to build a given vehicle is sometimes limited to the visible aesthetics that the choice of aluminium, steel, polymers or composites bring to its exterior. Their thoughts may extend to their impact on fuel economy and emissions and/or the environmental impact of their production. For some purchasers, recycling or disposal at the end of the road is another factor considered.

Under each vehicle’s skin, of course, a large range of components contribute to the qualities and efficiencies of a car, SUV or truck. Aluminium extrusions have long been an important part of that mix, but major suppliers of them, such as Hydro Extrusions, have plenty of ambition to extend their use by the automotive industry, particularly in support of the ‘megatrend’ towards electrification.

Multiple applications

Hydro Aluminium has a very large global network of many dozens of extrusion plants, both large and small, and often specializing in particular types of extrusions for specific markets by sector and/or geography. Many of them were formerly Sapa works before Hydro wholly acquired that business in 2017.

The automotive sector accounted for about one-sixth (17%) of the company’s total annual turnover of 1.27 million tonnes of extrusions in 2019, and that share is likely to increase slightly in 2020. “We do see the automotive segment as an area where we are seeing some growth,” said interim executive vice president Erik Fossum. “Unfortunately, 2020 has been a difficult year because of Covid-19, but we do see an increase in the figure that we are supplying to the automotive sector,” he noted.

Existing automotive applications for Hydro’s extrusions include heat exchange components for air conditioning and radiators, structural components, and parts for battery-unit enclosures and battery cooling components for electric vehicles.

It is an established range that Hydro continues to expand. Highlighting one of the most recent additions to that range in the past 12 months, Fossum pointed to high-voltage cables for the connection between the charger and the battery in electric vehicles.

“This solution has traditionally been provided in copper and a lot of the OEMs are still producing in copper, but we are starting to offer aluminium solutions for this and that is catching on quite quickly. That is something we believe in quite strongly in going forward,” he said. Hydro’s precision tubing segment produces them, based on both precision tubing and coiling technology, he explained.

“We are not yet a producer of a full battery case solution to customers,” said Hydro Extrusions vice president automotive in Europe Piotr Chmielewski. “It was our decision to not be the full integrator here, but we have very recently launched new projects for the different components of the battery case, which we then supply and they are part of the complete battery boxes,” he elaborated.

While these extruded products are directly associated with the ‘e-mobility system’ of electric vehicles, Hydro provides many others used for structural components of both conventional and electric vehicles. Crash management systems are one example.

Crash management systems

“We have a very good penetration of the car if you look at the components we are supplying,” said Chmielewski. “If you look at a map of a car showing where aluminium is used, I would say you will not find a component which we are not supplying,” he added.

Impact absorption at the front of a car is one part of the crash management system in which Hydro specializes. “The Nordic plants are growing in the automotive sector and are more specialized in the more sophisticated markets, where you have the crash alloys involved, and are really delivering to the majority of the European OEMs,” he noted. “Some of the products we deliver directly and some of them we deliver as a Tier 2, both from our Hungarian and our Nordic plants. We have a well developed product portfolio,” he added.

Front-bumper products are also part of the range, “which we are also supplying as part of the crash management system, and we recently booked some for main models being built in Europe,” said Chmielewski.

“We are also very well prepared if you look at the special aluminium alloys – both high-strength alloys and crash alloys are really our speciality. We have high competences using our R&D and innovation and technology center in Sweden to develop the new alloys and to follow the automotive OEM alloy requirements,” he elaborated. “We are able to supply each alloy which is currently needed by automotive OEMs. We are certainly certified to produce the whole range of the alloys needed by the different plants.”

Aside from the ever-present demand for vehicle light-weighting, regardless of the means of vehicle propulsion, Chmielewski identified strength, particularly for crash management. “The alloys are called different things by different OEMs, but we go up to 360 MPa yield strength for some alloys. We go up to 280 MPa as more standard, but the 360 MPa alloy is really strong and very well prepared for automotive presses, which is really our speciality I would say.”

Working with OEMs

While every aluminium extrusion for any sector has to be fit for purpose and meet minimum specifications, the demands placed on those used for automotive applications are much higher than those produced, say, for a small domestic greenhouse. Rather than basic commodity products, automotive extrusions are part of a highly specified engineering solution and the level of co-operation needed between their suppliers and OEMs is consequently high.

Vehicle design demands simultaneous engineering between automotive OEMs and their material suppliers. Historically, such activity was mainly the preserve of big laboratories undertaking physical tests. Nowadays, much more can be achieved through computer models.

For Hydro, its international R&D facilities play a key role in satisfying automotive customers. “What we see now is that [early-stage engineering] is moving towards simulation and modelling. What we have done internally is to focus, both in Europe in Finspang, Sweden, but also in Troy, Michigan, USA, to increase our simulation and modelling capacity,” said Fossum. “This is the way we are really supporting our customers, and especially towards the very strong, growing electric-vehicle segment,” he added, stressing this approach has proven particularly important for new electric-vehicle manufacturers because they have less resources than the long-established automotive OEMs.

The combination of the focus on modelling capacity across the whole of Hydro with the company’s decades of experience in materials science provides best value to the automotive sector, said Fossum, also supporting the growing expectation for new-model design lead times to get ever shorter.

Chmielewski concurred with the growth in importance of simulation and modelling, but added, “In Europe, we are still looking to the simulation approach, but we are also looking at our design center in Finspang, Sweden, where we have also installed something unique, because we have our own small casthouse and press, which is able to work on completely new alloys in a practical way – from the casting through to the extrusion.”

“But for e-mobility it is more work for the standard parts,” he explained. “So simulation is the main area of the support, but we are also very much on the practical side, having a lot of core equipment.”

Given all of the research work and ongoing customer support that suppliers of aluminium give to automotive OEMs, how do they price to reflect the costs associated with that? While acknowledging that such costs have to be accounted for, Fossum said, “It is a little bit challenging to discuss that.”

“There are a lot of resources going into the final product that we deliver and a lot of costs before we get to the production phase. So naturally you cannot just look at the cost of the production phase. You have to factor in that there are a lot of R&D costs on our hands before we get to the final product. There is of course a mutual understanding of this, but there will always be a discussion where the OEM will break down the process and try to evaluate the value for them of the different steps, but they are professionals and they know this very well,” he explained.

Perfecting the surface

Chmielewski said that Hydro is organizing the way to cover the whole value chain. “So we are very much focused on the alloys, and extrusion is a core competence of course, from the casting to the extrusion, but we also have a very well prepared and supporting group on the surface parts.”

Such visible extruded parts require high surface qualities and have been developed with some customers for a variety of applications, he added.

There are specific plants within Hydro Aluminium that are specialized in the exterior parts and achieving the high-quality surface finish those require. “There we have really good developments to go up to the specific pH requirements. We can go pH13.5, even up to pH 14.0, which is really the maximum in the market and is quite unique. We have quite a good market share over here supplying to probably all of the European OEMs having, with specific roof rails, more than 20% of the market share,” said Chmielewski. “So this is a niche product where within Europe it is more the value rather than tonnage driven. This is an important segment for us I believe – a unique opportunity of how we can make the jewellery out of aluminium for cars!”

The pH scale is used as a measure of the alkaline resistance of the surface treatment to the chemicals to which the aluminium components will be exposed during their use on a vehicle, such as soap or detergent in car washes and the salt used to treat roads in the winter.

Exposed aluminium parts include window trims, around the perimeter of windows, as well as the roof rails on top of the car. “We are well placed in this market and one of the main players.” The roof rails are standard components and roof bars, supplied by other companies, are good examples of exposed aluminium automotive parts.

Focus on recycling

Developments in automotive designs combined with public environmental concerns and tighter regulations on handling and shipping scrap materials internationally are obliging metal producers and automotive OEMs to consider the full life-cycle of vehicles more than ever.

A key consideration for aluminium scrap, whether prompt material generated during manufacturing or post-consumer metal, is the avoidance of mixing up alloys and thus losing the valued properties of each alloy type. While there are some notable examples of factories rigorously separating trimmings, offcuts, turnings etc., such care is not taken by all, while ELVs present a wide range of materials and alloys to the scrapyard and, commercially, the cost of separation has to be compared with the value of the materials segregated.

Fossum summarized the picture: “I think we would like the OEMs to be even more disciplined in terms of segregating the scrap. This is a cost issue. As long as there is a demand from the foundry side of the business there will always be an opportunity to not invest in the segregation of scrap.”

Looking longer term, over the next decade, he thinks there will be a requirement to do so. “And I think also that you see some push from the OEMs now to focus more on recycling. That also mirrors back on them because then they also need to take this seriously,” he added.

“At one [future] point in time, because we have been thinking about this seriously, our so-called primary foundry alloy (PFA) sink will be full, with not that much demand for foundry any more, as engine blocks and that segment will be declining with the evolution of e-mobility, and then I think this will force itself,” he predicted. But he reiterated Hydro Aluminium’s desire to see the OEMs be even more disciplined in terms of segregation of the alloys before then anyway.

Chmielewski concurred: “Over 70% of aluminium ever produced is still in use and it just takes 5% of the original energy [to produce it] to recycle, so that is the key. If there is better discipline, then we will have a better carbon dioxide footprint, and so more aluminium used and not mixing in materials, it will be easier to segregate at the end.”

Hydro Aluminium as a group is promoting the use of low-carbon primary aluminium through its brand REDUXA, with a carbon footprint of 4.0 kg for each 1 kg of aluminium, but it is also promoting recycled aluminium through its brand CIRCAL, which is made with a minimum of 75% recycled, post-consumer aluminium scrap.

“As a company in the primary segment, we are focusing a lot on recycling post-consumer scrap,” said Fossum. “We already have LIBS (laser-induced breakdown spectroscopy) equipment at a plant in Germany, and that is an area that we focus on growing in. We really believe in this, but to really succeed in recycling you need to establish a good system,” he explained. “Here you really need good discipline. I think there is a good development in terms of industry discipline, but there is still quite a way to go,” he added.

“This is an area that we have a strong focus on in the primary part of our business, and we will grow the focus in the extrusion part of the business because we also already have quite an extensive remelt for billet production in casthouses in our extrusion business, both in the US and in Europe,” he stressed.

Joining it all up

Automotive extrusions achieve their full value when they are incorporated in finished vehicles of course – a step that inevitably involves joining them to other components, which are not always made from aluminium. A science in itself, the process of joining materials can entail adhesives, fasteners or welding, which are sometimes used in combination to create a finished component and locate it in an assembled car.

While the traditional use of rivets remains an established option for joining aluminium, the technologies for connection and bonding joins has advanced in recent years and remain an area of development. “We are really focused on more friendly joining technologies for joining aluminium itself,” said Chmielewski. “Notably friction stir welding, which is key for the bigger structures and especially for battery frames,” he added.

Given that a mixture of metals and other materials is used in vehicles to get the best performance from them, how is Hydro contributing to the need to accommodate that mixture, particularly when it comes to means of bonding or joining such mixed materials? While aluminium companies are naturally reluctant to highlight that need, preferring to focus on their own metal and its alloys, Chmielewski confirmed mixed material bonding does get some attention. “I would say we are not so much focused on joining aluminium with other materials, but there is some development work with the different technologies, but we are not really so advanced that we really can provide an example,” he said.

“The main focus is to find the right means of joining aluminium itself – the most cost-efficient, the most user-friendly means. That is the reason that the biggest focus is on the friction stir welding, but we also have other joining technologies and hot gas forming, where we try to find the way to be more attractive to the customers and how to offer something unique that will help both them and us to reduce the cost,” he added. Electromagnetic pulse joining and other ideas are being looked at, “So we go even to some more extreme ideas, but we still prefer to join aluminium with aluminium rather than with other materials!”

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