Advances in Lightweighting

“ThyssenKrupp.”

I’ll admit that when I heard that ThyssenKrupp (thyssenkrupp.com) had conducted a project called “InCar plus,” I figured that it had something to do with steel. Given that there were more than 40 projects involved, I figured that they really did a lot of work on and with steel.

And so when I meet with Dr. Axel Grüeklee, InCar plus project manager, I assumed—incorrectly—that he is going to show me an assortment of steel coupon samples or maybe stamped parts. And not much else.

“This was the biggest R&D project in our company for the auto industry,” he says. “It included participation of eight companies in our group.”

Yes, they develop steel. Yes, InCar plus includes steel-related developments. But know that there is a whole lot more. Did you know that ThyssenKrupp produces assembled camshafts, cylinder head modules with integrated camshafts, crankshafts, steering and damping systems, springs and stabilizers, and assembled axle modules?

You’ve heard of Bilsten shocks? They’re from ThyssenKrupp Bilsten GmbH.

Yes, more than steel.

Grüeklee explains that for the projects they undertook, the objective was to better the existing state of the art in one or more ways. That is, they wanted the developments to be lighter, more cost competitive, higher performing, or more sustainable than the best out there.

Which means that the developers didn’t limit themselves to a steel portfolio, although some steel advances truly make for big advantages.

They developed a steering column. Through the use of carbon-fiber reinforced plastic for components they were able to reduce the weight of some components by as much as 60% and the overall weight of the assembly by 25%.

There is an adjustable cam element for variable valve lift systems. Grüeklee notes that this is something that is ordinarily produce with steel, but they’ve created a hybrid system that utilizes both steel and plastic. As a result, there is a weight save of 30%. “Due to the lower weight, there can be cam lobe switching at higher rotational speeds. This can result in an additional 5% fuel reduction because of the ability to shift more quickly.”

There is a steel that they’ve developed—but this material for various exterior body applications, named LITECOR—is actually a steel-polymer sandwich. One example is a sheet that has a total thickness of 1 mm, with there being 0.2-mm sheets of steel on either side of a 0.6-mm plastic (a polyethylene polyamide material). Grüeklee says there are several advantages of this material, which can be a weight save on the order of 40% compared with conventional steel. For one thing, he says that it is essentially the same weight per area as aluminum, but is less expensive. For another, it is easier to attach to other steel components than aluminum is because there isn’t the issue of potential galvanic corrosion, so fasteners, spot welding or bonding can be readily used. And the forming can be performed in the dies that are ordinarily used. The gauge of the material can be calibrated to meet application requirements (e.g., a hood’s material is different than a roof’s).

Grüeklee notes, “I am quite sure if you built a pickup truck with hot forming”—ThyssenKrupp has extensive expertise in this process for ultrahigh-strength steel processing—“and sandwich material, you’ve have nearly the same weight but a better cost situation.” He’s referring, of course, to a certain aluminum-intensive pickup.

“Nobody wants these steel wheels because they don’t look nice,” Grüeklee says, pointing to some steel wheels that are rather style challenged. Consequently, the aluminum wheel has pretty much become the standard. So what they’ve done is to create a wheel that uses a conventional steel rim and a stylized wheel disc that can be welded in place. While the wheel doesn’t look precisely like a machined aluminum component, it is far more attractive than what has been the case for steel wheels. And there is the not insignificant fact that where the aluminum wheel weighs 10 kg, the steel wheel comes in at 8 kg.