Experts charged with lightweighting interior vehicle parts are rethinking what a car interior means and how parts can function in multiple ways to achieve aesthetic and operational goals.
The topic was part of the Plastics in Lightweight & Electric Vehicles conference, held Nov. 7-9 in Livonia, Mich. “Sustainable” and “conscious consumerism” no longer are trends or buzzwords. They have become part of the thread of culture, especially as governments issue higher standards for emission control and miles per gallon.
In design thinking, customer, consumer and commercial needs are met along with sales targets.
“Plastics always has been a designer's friend because we can do so much with it,” said Tom Gould, design director for North America at Johnson Controls Inc. of Plymouth, Mich.
The design approach to lightweighting looks at techniques such as biomimicry. For example, to develop a lighter prosthetic leg, designers might consider how bird nests are built in nature. By mimicking the webbing and intricacy of the interior of a nest, designers can achieve lightweighting goals — while also making the leg highly functional.
In rethinking a car interior, a lightweight headliner and trim garnish created with 100 percent PET has no cover and can act as an audio system.
“What normally would have been hidden, we're bringing forward,” Gould said. As part of the design process, experts like Gould look at new ways to process polymers. In the Herman Miller furniture line, for example, a molded plastic mesh, frameless seat back gives inspiration for lightweighting auto interior parts.
Design experts can use multiple forms of plastic for one product. For example, a functional film on an overhead console may reduce mass and consolidate parts. Polypropylene thin film produces a good-looking and durable finish to a PP floor console frame, eliminating the need for heavy steel structures. In this way, parts are achieving enhanced performance. Composite plastics enable a thin lightweight seat structure.
To apply principles such as these, companies must build an innovative team around its problems.
“Get design to the table,” Gould said. “Increase collaboration with unlikely partners, with an intention to work it out. Push to create products and experiences that matter. Push design to solve. Science without creativity doesn't work.”
The powertrain and chassis area of vehicles has seen a 40 percent increase in the use of plastics in the past 10 years, said Maurice Sessel, senior vice president of engineering with International Automotive Components North America of Dearborn, Mich.
“That will only increase,” he said, noting that the instrument panel alone has a lot of room to cut weight.
“The cross-car beam offers an excellent opportunity for weight reduction since it accounts for greater than 30 percent of the IP weight allocation,” Sessel said.
There remain opportunities in thin-wall uses. Experts have seen weight reduction of 5-15 percent using blowing agents when structural integrity is not compromised. The technique has been used in non-Class A surfaces.
Nanotechnology has been used in the auto sector for some time, but there are some processing challenges that must be worked out. In carbon-fiber reinforcement, a compression molded mat technology using reclaimed carbon fibers achieved 60 percent energy savings vs. glass-mat technology.
Amit Kulkarni, senior innovation manager with Faurecia Automotive Seating North America in Troy, Mich., said plastics must compete in cost and weight for OEMs to look at it.
How can plastics accomplish breakthrough designs? Kulkarni pointed to several examples, including a structural head restraint that can be customized and lightweighted by using foam. In a plastic composite back frame, an OEM gets about 20 percent weight reduction, a 1-inch-thinner package and a 10 percent reduction in assembly time.
“The key for plastics to be viable in this industry is part integration for weight reduction using plastic/composite materials,” he said.
Kipp Grumm, advanced development engineer with BASF Corp. in Wyandotte, Mich., talked about thermoplastic overmolded continuous fiber structures. The concept combines advantages of injection molded thermoplastics and continuous fiber rein- forcement to create strong, light parts that are cost efficient with good stiffness, environmental benefits and quick manufacturing cycle times.
“One application for this is the composite seat back to replace the current steel structure,” he added.