Automotive ingenuity

One of the premier showcases for innovation in automotive manufacturing is the Society of Automotive Engineers (SAE) annual technical conference and exhibition in Detroit. This year’s show, while highlighting an impressive array of advanced manufacturing capabilities, also featured a number of significant plastics-related developments with near- and longer term implications for suppliers. This, from the show floor, is our selection of the top five trends, along with other news.

Wider use of thermoset and themoplastic composites in structural and other non-traditional applications

Hexcel Company, a manufacturer of composite materials, displayed a set of composite leaf springs which weighed 60 percent less than leaf springs made of steel. The leaf springs are molded in a single step using epoxy pre-preg material. The pre-pregs are supplied in roll form and are cut to shape before being placed into the mold tool. Composite leaf springs absorb energy more than steel and have greater fatigue resistance.

Hexcel also displayed a drive shaft molded from glass- and carbon-filled epoxy resin. According to Richard Roberts, director of business development, a composite drive shaft, in addition to being lighter in weight than steel, is more efficient to manufacture. “Epoxy transfers power better than steel, which means you don’t have to mold the shaft in two pieces.”

Roberts points out that the composite technology used to make the automobile drive shaft is basically the same as the technology used to make composite tennis rackets and golf clubs. Roberts notes that over the past four or five years the cost of carbon fibre has decreased by 20 to 40 percent, depending on the type of fibre used. Composite drive shafts have been used on custom-built rally and sports cars for years. With the cost of carbon fibre dropping, there is renewed interest, accompanied by lots of development work, in using composites in a commercial drive shaft application.

Figures compiled by The Automotive Composites Alliance (ACA) show that use of reinforced thermoset composites by automakers has nearly doubled in the last decade. The association projects OEMs will use 318.4 million pounds of reinforced thermoset composites in 2000 and 467 million pounds by 2004, a predicted increase of 47 percent during the next five years.

The ACA reports that composite parts and materials have lower tooling investment costs compared with sheet metal, are lighter than steel, allow greater design flexibility and have superior corrosion resistance than steel. ACA chairman Mike Dorney says the cost efficiencies afforded by composites are maximized in low- and medium-volume applications, when production runs are at or under 200,000 vehicles.

Common architecture/mass customization

Lear Corporation, which has been doing development work in modular interior systems for a number of years, formally launched an ambitious new production concept based on modular design called Common Architecture Strategy (CAS). CAS is the base structure for five interior systems–instrument panel and console system, seat system, door and interior trim system, overhead system, and flooring and acoustic system–linked by a network of electronic and electrical distribution systems. Lear says the system will eventually allow buyers to literally custom create their own personalized vehicle interiors. From a production standpoint, Lear claims CAS will make global production across all brands and classes of vehicles feasible.

“We’re installing seats right now in two to four hours after we get the order,” Lear chairman Ken Way said in an interview. “We have the ability to do this already on some products.”

The key to the system is a combination of common modular components and reconfigurable interior parts. For instance a mini-cassette module is a door hardware carrier that provides common architecture for all four door and interior trim panels, alleviating the need for multiple tooling of door components. The common elements of the module include window lift hardware, electrical wiring, inside door release handle, moisture barrier and trim panel and arm rest attachments. Consumer choices are a covered map pocket, flush-mounted storage bins, removable trash bins, CD storage pockets and trim options. Nearly all reconfigurable items in the door module are plastic or plastic/fabric combinations.

The system was demonstrated at the show where a team reconfigured a complete vehicle interior for two different looks and market segments-the “New Lux” interior geared for Baby Boomers, and a “Gen Y” style aimed for the under 30 age group.

The New Lux luxury trim panel system has controls that are ergonomically designed, featuring color-coordinated leather, suede and vinyl-wrapped components.

The Gen Y door and trim panel system featured colorful orange translucent plastic inserts that match the top of the instrument panel and a light-blue translucent plastic trim that offers a soft-touch surface in the arm rests. Windows levers were designed in the style of joysticks.

Lear says there is considerable market demand for personalized interiors. The claim is based on market research the company conducted on Generation Y consumers, a demographic group of 80 million potential vehicle buyers.

The end of seats as we know them?

Today’s typical automotive seat assembly is a combination of fabric, foam, springs and other components, all of which add weight and cost. This could change in the near future as several suppliers have reportedly expressed high interest in a seating fabric system manufactured by The Quantum Group Inc., located in Greensboro, N.C.

Quantum uses DuPont’s Hytrel thermoplastic polyester elastomer to manufacture a variety of high-strength, flexible fabrics. The fabrics are currently used in a line of high-end office chairs. When stretched over a tubular metal frame the fabric provides an ergonomically-correct, but comfortable seat. Applying the same seating material and design to automotive seats could save on as much as 30 lb. of foam, according to Larry Cole, DuPont Engineering Polymers executive product planning manager, interior systems. Higher costs for the fabric would be balanced against cost savings on foam and springs, as well as weight savings.

Quantum president Jeff Bruner notes that Hytrel, a high-modulus, low elongation material, is often combined with a low modulus, high elongation material, such as DuPont Lycra, to create a fabric that provides both good support and comfort for the body. Other types of fibres are woven into the fabric to provide color, natural textures and dissipate static.

Recycling

Sixty-nine percent of automotive designers and engineers believe recycling will play a major role in the automotive industry over the next five years, according to a survey conducted at the show. Underscoring the growing importance of automotive recycling issues were the large number of papers on recycling presented at the show’s technical sessions.

Richard Kaskel of B&M Plastics, Inc., noted in his paper (#2000-01-0738) that low price of a recycled material doesn’t necessarily mean low profitability, provided mass and market requirements for the material are met up-front. For example, the low cost of recycled steel (about two cents per pound) has not prevented a large number of companies from collecting large mass amounts of this commodity, for which there is a market, which in turn provides a profit.

Market demand, rather than market supply, is the key to successful recycling of automotive plastics, says Kaskel. Creating market demand in turn depends on the ability to make materials that meet pre-defined physical and performance requirements for specific applications. Kaskel says B&M sells over 40 grades of recycled engineered thermoplastics into markets such electronics, automotive, lawn and garden, marine and others.

A number of researchers from Toyota Motor Corp. described a new method of recycling two-layered interior surface materials composed of a TPO skin and cross-linked PP foam (#2000-01-0741). Previously, recycled material obtained by
melt-blending TPO skin and PP foam could not be reused for TPO skin because of its appearance. The new technology uses a reaction biaxial extruder with a reaction agent that can decompose the network structure of PP foam. As a result PP is dispersed into TPO uniformly and the recycled material has properties and an appearance similar to virgin TPO, say the researchers.

Reprints of these papers can be obtained by contacting SAE at 724/776-4841 and referring to the paper # given above.

More uses for molded-in color material

Front and rear bumper fascias of the Dodge and Plymouth Neon are presently molded from DuPont’s Surlyn Reflection Series supergloss alloy. But, as one large supplier at the show indicated, many molders still have concerns about the gloss retention and color matching of metallic shades for molded-in color material.

Rob French, development programs manager, DuPont Automotive, says strides have been made in both gloss retention and color match of molded-in metallics. With metallics, French notes, the key to success is good mold design.

“It’s a matter of saying from the start, how are we going to design the mold and position the gating to maximize the appearance of the metallic pigment in the finished part,” French says.

French notes that many molded-in colors of DuPont’s Surlyn Series have received approval, and can be used in existing tooling designed for painted parts.

A research group from Toyoda Gosel Co. presented a technical paper which specifically addressed flow mark reduction of metallic colored polypropylene (#2000-01-1127). The group was apparently able to manufacture a non-painted metallic side molding without flow marks by using a grade of PP with low melt viscosity and wide molecular range distribution. They also used a metallic pigment with small mean particle size and low concentration. To order the paper call SAE at 724/776-4841.