SMC ... from design diversity to disassembly

Tough, rigid and surprisingly flexible and adaptable, SMC is becoming the material of choice for many new applications on higher volume vehicles.

Take the exotic hood of the new Ford Mustang with its raised center section that tapers back to a scoop on each side. The cost of tooling for steel parts for this curvaceous piece would have been prohibitive.

"SMC allowed us to execute exceptional styling at a 25% weight and 60% investment reduction on the hood," says Art Hyde, body engineering manager for the Mustang Platform.

SMC, steel work together

And engineers report SMC is a great team player, too. It often is partnered with steel in new vehicles because unlike other plastics it expands and contracts at the same rate as steel.

"SMC is compatible with the steel box and inner structure of the F150 flareside pickup," says Craig Schmatz, Ford Motor Co. product design engineer. Ford uses SMC for the fenders of these specialty F-series trucks. General Motors Corp. also uses SMC for its flaresided pickups.

SMC and steel have the same coefficient of expansion, making them a "perfect match for each other," Schmatz says.

Another desirable attribute of SMC is that it can be used to simplify designs. It enables designers to combine several parts into a single piece or develop a multi-functional unit.

Radiator support module

Roy Sjoberg, executive engineer for Chrysler Corp.'s Viper project, cites the radiator support for the exotic Dodge Viper as an example. He says Chrysler first used SMC for grille opening panels and then used the technology to design an SMC radiator support for the trend-setting two-seater.

"The radiator support is a total module that includes the evaporator system and die coolant system," Sjoberg says. "SMC has the ability to modularize with very few components and take it to the job."

Flexible fenders

The 1995 Lincoln Continental marks a new high point for SMC. Its fenders are made of new flexible SMC. This state-of-the-art material has double the flexibility and impact strength of traditional metallics. But the new fenders don't need any special attention; just like those made of conventional SMC, they are bolted onto the body structure and prepped and painted right along with the rest of the vehicle.

Ford engineers say they also appreciate the considerably lower cost of tooling for the SMC fenders (more than a 40% savings) compared with steel.

There is life after life, and SMC molders can prove it. Today they are recycling more and more of their pre- and post-consumer waste and can make new SMC from the old. The more recycled SMC used in a vehicle, the lighter the part.

The SMC Automotive Alliance (SMCAA) has taken a leadership role in identifying, developing and demonstrating suitable processing technologies for recycling SMC. The Alliance's goal is to punch its program into high gear so recycled SMC can be used in high volume as a raw material for new SMC, says SMCAA Chairman Eldon D. Trueman, vice president of sales and marketing for The Budd Co. Plastics Div.

SMC has an advantage over some other materials. It is lighter-weight, tipping the scales at 25% to 40% less than steel, and tooling for SMC parts typically costs 60% to 65% less than steel. But SMC's recyclability has been questioned. That's a misconception the Alliance is digging into its wallet to correct. More than half of the annual budget is devoted to the recycling effort, and it's gaining converts.

Recycled filler used

General Motors Corp. used recycled composite filler in the inner panels of the 1993 Chevrolet Corvette, becoming the first automaker in North America to put recovered SMC on a vehicle. More recently, Chrysler Corp. pioneered use of composite filler in painted interior body applications on the full-size Dodge Ram Van and the spoiler on the Chrysler Neon passenger cars.

Ford Motor Co. is using recycled filler in the engine cover on its Econoline vans, a grille opening panel on the Ranger pickup and a hood inner panel on the Aerostar minivan. It also is considering ways to help collect post-consumer parts within the Ford network.

By the end of 1995, the auto industry is expected to use more than 4 million lbs. of recycled composite filler. The goal is to use all the scrap, which amounted to 7.5 million lbs. in 1994, or 3% of the total pounds generated. As the demand grows, so does the need to expand SMC recycling operations.

Life from the ashes

During the past two years, the SMC Automotive Alliance has coordinated commercial operations within molding facilities to reuse SMC scrap. Some of its members are venturing even further into the recycling community. Owens-Corning recently acquired an equity position in Oakville, Ontario-based Phoenix Fiberglass, North America's first glass- fiber recycling facility.

Phoenix's process recycles post-industrial, cured SMC into four raw materials: two hybrid glass fiber reinforcement products--a half-inch chopped strand and a short fiber product--and two grades of filler. The remaining cured resin and filler are milled and separated into two grades of filler. The products are marketed to the North American composites industry.

The technology does not use heat or cryogenics, so it is cost-effective and allows Phoenix to market the glass fiber at a price advantage. Phoenix may someday also branch out into recycling post-consumer waste.

SMCAA has run about 30,000 lbs. of post-consumer material through the Phoenix facility.

"With the exception of grossly contaminated input, the process is very tolerant," says Trueman, pointing out that SMC is more tolerant of contamination than most other plastics. "The output is viable even though components have been run through the process with adhesives, hardware and paint still attached."

Typical automotive SMC is 40% to 50% filler and 20% to 30% fiber by weight, se significant quantities of recycled filler or fiber can be included with some flexibility in composition. Composites such as SMC provide flexibility and tolerance in establishing an overall automotive recycling plan at a level not achievable with some other plastics. SMC fillers are reusable without sacrifice in physical properties.

SMC truly is shaping vehicles, both in this life and the next.