The auto industry is very focused on getting stronger and lighter, which is something most of us would like to do! They call it lightweighting, but it’s not about cutting calories. What they’re trying to do is build cars and trucks that weigh less than previous models yet provide greater strength. This entails using metals new to the automotive industry and learning how to form them into complex structures.
Weight and strength matter for three reasons:
- Gas mileage. With the EPA requiring an average of 54.5mpg by 2025 manufacturers are exploring.every option to save weight Switching to stronger steel means they can use less of it. And it’s not just steel: high strength aerospace-grade aluminum has a part to play as well.
- Safety. Crash test results make headlines and buyers pay attention, so auto companies are very focused on safety. Plus, new tests and regulations are pushing them to build stronger vehicles, but they need to do that without increasing weight.
- Payload. If you’ve ever carried a heavy golf bag or cooler you’ve thought about payload. The lighter the container the more you can put in it. That’s important in cars and trucks, but maybe even more so in vehicles like RV’sand utility trucks. A lighter but stronger structure means more tools, equipment and amenities.
The New Breed of Metals
A lot of acronyms are used to describe these higher strength steels. The main terms you’ll meet are Advanced High-Strength Steel (AHSS) and High Strength Steel (HSLA), which we discussed in “Mighty Metals: How Super Alloys Have Changed the Welding Process.” Other terms used for these new generation materials include Dual Phase (DP) and Transformation-Induced Plasticity (TRIP)steels. These are used in places like roof rails and seat frames.
Metal producers are working on stronger aluminum alloys too. You may see the terms, “5xxx series,” “6xxx series” and “7xxx series.” These describe progressively stronger grades. 7xxx for example is an aerospace alloy used for the door side crash beams in the new BMW i8. It’s so strong that it has to be formed at elevated temperatures, and that raises issues for metal fabricators like us.
“Stronger” usually equates with “more brittle” and that’s certainly true for these high strength metals. They work-harden rapidly, which makes them prone to cracking during forming, and increases press loads. That means distortion of both tooling and the machine is something to watch for. In addition, tooling tends to wear faster, and springback is more pronounced.
Another issue is that these metals are used in thinner grades. Consequently, wrinkling and distortion can become problems unless taken into account when planning the fabrication process.
None of these problems are insurmountable, but they do require careful attention to both press and tooling. A good lubricant helps, but so too does having the right equipment and forming at an appropriate speed. At the end of the day though, it’s really about having a deep understanding of both the material and the fabrication process.
Is Lightweighting Right for You?
At Wiley Metal we monitor metal fabrication industry trends such as lightweighting so that we’re prepared for questions. As a producer of parts like cone holders, man baskets, lightboxes and even license plate holders for utility trucks, semi trailers and RV’s we understand the impact of weight. If you’re interested in lightweighting these and other parts used in a range of vehicles, talk to us. We’ll walk you through the implications and help you make an informed decision.
Lose weight without dieting? Now that’s something we all want!