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Is the cost of lightweighting R&D worth it?

Clare Goldsberry

March 11, 2016

4 Min Read
Is the cost of lightweighting R&D worth it?

Lightweighting continues to drive innovation in the automotive industry and among suppliers developing components that use alternative materials. At last year’s Plastics-In-Motion conference, Dr. Marina A. Rogunova from Covestro (Leverkusen, Germany) spoke to trends in automotive, specifically lightweighting, which “leads the fuel-efficiency charge.”

IHS SupplierBusiness in a recent editorial noted a whole host of lightweight components that are being developed for new model vehicles. “GKN Driveline announced that it will equip the new BMW 7 series with its lightweight VL3 constant velocity joint (CV joint) system” that enables “rear-wheel drive platforms to save more than 4 kg of weight, while increasing torque capacity by 27%.” Global supplier Magna recently introduced “lightweight components the company is supplying to new Cadillac models, including carbon-fiber hoods, aluminum oil pans and high-pressure aluminum die-cast components.”

The SupplierBusiness editorial commented, “The automotive industry’s fundamental driver is the need to cut fuel consumption and associated emissions from vehicle use. Though alternative propulsion technologies have had some impact on emissions, it’s still clear that lightweighting will make up the majority of OEMs’ efforts to reach emissions targets.”

While aluminum is talked about for many vehicle components, plastics and carbon-fiber-reinforced components are a hot item. At the 2015 Plastics-In-Motion conference, Paul Hardy, Product Manager, Engineered Plastics Americas for A. Schulman, presented a number of strategies for lightweighting. According to Hardy, the average weight of plastics in a car today is estimated to be about 350 pounds, with plastics making up about 50% of the volume of a car but only 12% to 14% of the weight. “For every 10% in weight reduction, there is about a 5% to 7% fuel economy,” said Hardy.

However, Hardy noted that current improvements to fuel economy are heavily influenced by factors other than weight savings, such as engine technology, new metal technology and overall size reduction. Some other technologies for lightweighting that he pointed out are material technologies, such as MuCell, which has allowed A. Schulman to achieve up to 15% in weight reduction, according to Hardy; foaming agents, which can provide a range of 5% to 10% reduction; and gas injection—injecting nitrogen into the barrel during the molding process—which reduces weight by 3% to 8%. Carbon-fiber compounds have started to get pricing and products aligned to replace steel. “This has struggled some, but the technology is changing and seeing more use,” Hardy commented.

Down-gauging and thin-walling of parts can also produce lighter weight parts; however, it’s important to maintain the structural performance of the component. “Starting with a part design with thinner wall thickness in mind significantly improves the probability of success,” Hardy adds. “Often, to do this requires a plastic with a high flow rate to fill the part; however, this has a negative impact on the overall physical property performance.”

So, do we trade the physical properties that plastics are known to provide just to achieve a lighter weight and reduced functionality? At what point does the law of diminishing returns kick in and it becomes more and more costly to get fewer and fewer benefits? This question might also be asked by those trying to achieve sustainability through the use of bioplastics in various automotive components. What do you sacrifice in production costs? In performance?

An editorial in the Jan. 13, 2016, issue of the Wall Street Journal (“GM Speaks Untruth to Power”) by Holman W. Jenkins, Jr., raised some interesting points about this drive toward lightweighting. Jenkins pointed out that a “big factor—unless economics is a deluded field of study—is the forced diversion of billions in vehicle investment dollars into fuel economy, which Detroit should be loudly criticizing. Take the Obama rules requiring 54.5 mpg (from today’s 24.9) by 2025: These are expected, depending on how much testing fakery and loophole-exploiting the government allows, to cost auto makers $3,000 to $5,000 per car, crowding out lots of features consumers might prefer for their $30,000 sticker price.”

Another factor, from what I’ve researched, is that no one knows—in spite of all the computer modeling—just how much this nearly impossible mpg goal will reduce emissions or if it will even have anything but a negligible effect on air quality.

While it was interesting to attend the 2015 Plastics-In-Motion conference—and this year’s conference on May 8 to 11 in Charleston, SC, promises to be just as interesting—the R&D dollars being poured into lightweighting through alternative materials, thin-walling and down-gauging make me wonder if, at the end of the day, it’s worth it given all the unknowns.

About the Author(s)

Clare Goldsberry

Until she retired in September 2021, Clare Goldsberry reported on the plastics industry for more than 30 years. In addition to the 10,000+ articles she has written, by her own estimation, she is the author of several books, including The Business of Injection Molding: How to succeed as a custom molder and Purchasing Injection Molds: A buyers guide. Goldsberry is a member of the Plastics Pioneers Association. She reflected on her long career in "Time to Say Good-Bye."

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