We live in a multi-material world – facilitated by aluminium

Kaiser Aluminum’s Doug Richman provides a case for aluminium in the automotive industry’s future material mix. By Martin Kahl

For Doug Richman, one word sums up everything about the automotive industry’s lightweighting efforts: efficiency.

Richman is Vice President, Engineering at extrusion company Kaiser Aluminum; he also chairs the Technical Committee of the Aluminum Association’s Aluminum Transportation Group. In his view, efficiency refers to CO2 and to fuel economy, as well as to vehicle handling and performance.

The most obvious ways of reducing vehicle weight to achieve that efficiency, he says, are to either reduce the density of the materials that make up that vehicle, or to reduce the size of the vehicle.

Make it lighter or make it smaller

Smaller vehicles are lighter, but downsizing vehicles comes with added safety challenges. “A larger vehicle with more crush space manages energy in a collision outside of the passenger compartment. When the vehicle gets smaller, it becomes a much greater engineering challenge to keep the collision energy away from the passenger compartment.”

As well as the safety challenge of downsizing, there is a more immediate issue, namely a vehicle’s market positioning. “There are vehicle classes where downsizing is not an option because the market presence of that model requires it to be a larger vehicle. Luxury vehicles and pick-ups sell to markets that want large vehicles. Downsizing takes them out of their target customer segment.”

If it’s a value engineering programme, you can’t use lightweight materials. There is no material out there that’s going to be stronger, more energy absorbent and lighter and cheaper than what you are already using

Given the challenges of downsizing, the next option is reducing density – and that’s where aluminium comes in. Asked how aluminium can help OEMs balance the need for lightweighting with the need to cut cost, Richman provides an interesting but frank perspective: “If it’s a value engineering programme, you can’t use lightweight materials. There is no material out there that’s going to be stronger, more energy absorbent and lighter and cheaper than what you are already using.”

Famously held up as the ultimate example of switching from steel to aluminium, the aluminium-intensive body of the latest-generation Ford F-150 enabled Ford to produce a vehicle with a higher load carrying capacity and higher towing capacity than the previous generation. “You get more vehicle for that additional cost. The F-150 is not a value engineering programme, it’s a vehicle improvement programme.”

No mass reduction programmes ever involve cost reduction, says Richman, pointing out that if they did, they would already be in use. In the case of the F-150, which prices a few hundred dollars above the previous generation, “The fuel economy savings for the user quickly pay off that premium. In terms of the lifecycle cost of the vehicle, it’s a positive value proposition for the consumer. But the vehicles are better and more desirable for those customers, and Ford is seeing that in the marketplace.”

Big is beautiful, small is complicated

OEMs are able to absorb the cost of lightweighting in large and luxury vehicles; the challenge kicks in when lightweighting smaller segment vehicles, particularly the highly price sensitive A and B segments. “The way to reduce mass and cost is to make the vehicles smaller. If a car competes in an extremely price sensitive market and the customers are not drawn to it by performance and luxury features, the OEM is unlikely to deploy increased cost alternatives.”

The steel industry has done an amazing job of advancing steel for the needs of the marketplace, and the aluminium industry is doing an amazing job to make that happen

At this point, Richman pauses. “Let’s be clear – vehicle manufacturers still use considerable volumes of aluminium even in small cars, like aluminium engine blocks and heads, transmission cases, radiators and even wheels in some cases. The average vehicle in the US today is about 10% aluminium.”

We are living in a multi-material world

Rather than competing with other materials like steel, magnesium and composites, Richman sees a successful lightweighting strategy employing a healthy material mix. “We are in a multi-material world. We’re talking here mainly about the body, but most modern cars use aluminium castings and 80% of the aluminium in a car is cast. The next place to lightweight with aluminium would be in the body. 30% of the mass of the whole vehicle is made up of the body-in-white plus the closures – that is, the doors, the trunk, the hood and bolt-down fenders.

“Aluminium co-exists in a multi-material world with all those materials. The steel industry has done an amazing job of advancing steel for the needs of the marketplace, and the aluminium industry is doing an amazing job to make that happen.”

Indeed, he firmly believes the multi-material approach is the only correct way to lightweight vehicles. “The body structures that we’ve been working on for several years have a mix of steel, high-strength steel and aluminium. There are many places where aluminium makes very good engineering sense in the context of the trade-offs between cost, mass, energy management, safety, formability, styling, and many other issues. We’re all in this together – aluminium has its place, as do steel, high-strength steel, graphite fibre and in some places magnesium.”

Magnesium is interesting because of its volatility and its limited applicability – but every material has a limited range, adds Richman. “No material makes sense everywhere. You can’t make an aluminium exhaust manifold or muffler. And magnesium really is a material of choice for a specific application. It has a small percentage of the market, but tremendous growth potential.”

Forming a view

Like other materials, aluminium is formed in a number of ways for automotive applications, notably casting, pressing and – relevant to this discussion – extrusion. “Kaiser Aluminum is one of the foremost structural extrusion companies for the automotive industry in North America,” says Richman. “We specialise in highly engineered, structurally demanding products, such as bumpers, energy absorption beams and crash boxes. We produce parts for the F-150 body structure and for other aluminium vehicles.”

One of the key challenges for OEMs is to lightweight their vehicles in order to meet ever stricter fuel consumption and emission regulations, while also equipping their cars to meet ever stricter safety targets, often adding weight

Extrusion is one of the lowest cost means of producing a complex shape for specific applications. “In an extrusion we can create an incredibly cost effective, high structural integrity shape.” However, Richman concedes limitations to extrusion. “You can make an extrusion as long as you want, up to 120 feet, but it’s a two dimensional shape, in many cases requiring considerable post-processing. But the industry is learning how to use extrusions very creatively. Ford has done a great job with the extrusions on the F-150, using very advanced technology and complex shapes.” Extrusions may not fit everywhere, but “they do a wonderful job in the right places.”

Right material, right part, right place

An examination of lightweighting strategies always returns to the same tune: the right material for the right part in the right place. One of the key challenges for OEMs is to lightweight their vehicles in order to meet ever stricter fuel consumption and emission regulations, while also equipping their cars to meet ever stricter safety targets, often adding weight. That’s when the aluminium industry is called on to help, grins Richman. “Pound for pound, aluminium absorbs more than twice as much as steel, and stronger steel is even less energy absorbing. And by preserving the vehicle’s size, aluminium allows engineers to design larger crush space into a lighter vehicle.” If you have to add mass, is the message, then the less mass you add, the better.

R for repairability, r for recycling

Two ‘r’ initialled words always feature when discussing the wider merits of aluminium use in automotive applications: repairability and recycling.

Repairability is an issue for the adoption of any new material, where franchised and independent repair shops require not only new or additional equipment, but also specific training and certification. However, while repairing aluminium vehicle bodies may be very different to repairing steel bodies, it’s not any more difficult, notes Richman. “The repair procedures are different but the skillset is similar to that for steel bodies.” 70% of the repair work on any vehicle, steel or aluminium, is a remove-and-replace activity; the currently low percentage of certified aluminium repair shops is growing quickly; the OEMs are increasingly successfully engineering their steel and aluminium vehicles for repairability in the field; and they demand that repairers working on their vehicles be appropriately certified.

When it comes to recycling, there are two aspects to consider – the recycling of end-of-life vehicles (ELVs) and manufacturing material recycling. “In terms of vehicle recycling, more than 93% of all the aluminium in all the automobiles in North America is recovered and put back into service. Only a very low level of metallic aluminium goes to landfill. It’s incredible what the industry is able to do to recover metals – and that’s true also for steel, copper and magnesium.”

Steel will remain the big player for the foreseeable future, but we’ll see more cars with steel bodies and aluminium doors and trunks. The mix will include more plastics, more composites, more aluminium and some growth in magnesium

Manufacturing material recycling presents even higher recovery opportunities, says Richman. “The OEMs generally put about 65% of the metal they buy into a part. Ford buys about a billion pounds of aluminium annually to make the F-150, and 35% of that becomes pumped scrap.” To recover this pumped scrap – the material off-cuts and waste created usually in the stamping process – Ford has begun capturing and reselling it. “No OEM or supplier knowingly throws aluminium into landfill. It’s worth way more to sell it back to the aluminium company.”

We’re all in this together

Given Richman’s obvious interest in aluminium, his views on the likely material mix in the automotive industry of the future are interesting. On average, aluminium accounts for about 10% of the kerb weight of the fleet in North America, he says, referring to the unladen weight of a fully equipped vehicle, and it’s a similar percentage in Europe. “That includes aluminium bodied vehicles, engines, transmissions and all other components. We think that 10% total will grow to around 14% by 2025, with all of the growth in body-in-white and closure panels.

“Steel comprises about 65% of the kerb weight of the average vehicle in North America and while that may come down somewhat, that combination will still be well over 50% of the total mass of the average vehicle. Steel will remain the big player for the foreseeable future, but we’ll see more cars with steel bodies and aluminium doors and trunks. The mix will include more plastics, more composites, more aluminium and some growth in magnesium. We’re all in this together. We grow, the OEMs put out better products every year – and the consumers win.”

This article is part of an exclusive Automotive World report on lightweighting. Follow this link to download a copy of Special report: Vehicle lightweighting

Close
Close