Think of auto composites suppliers as being on an unending uphill climb.
For every breakthrough in processing or sales that allows them to move forward, there are changes in requirements for painting or increased challenges from metal that send them back down.
While Toyota Motor Corp. provided a major win for composites by buying into sheet molding compound for the bed of its Tacoma pickup truck, an ongoing switch to powder-based paint primers is cutting suppliers' abilities to sell automakers on SMC for hoods, fenders and other body panels.
While structural reinforced injection molding has won new life in the flooring system for DaimlerChrysler AG's minivans, General Motors Corp. backed off on offering the material as a pickup bed option.
And although automakers increasingly are turning out low-volume niche vehicles to grab consumers' attention, improvements in steel and aluminum production are making those materials even more competitive in an arena that once heavily relied on composites.
``We've made a lot of progress, but the bar has continued to move, and that's the toughest part,'' David Mattis, GM director of materials and appearance engineering, said during the Society of Plastics Engineers Automotive Composites Conference.
``You set a goal and a target, and you can reach that target but look around to see that the industry's changed, and the goal wasn't high enough. That's part of the issue here that we have,'' Mattis said.
Composites are making some important strides, automakers and suppliers said during the conference, held Sept. 14-15 in Troy. But the materials also are facing challenges even for vehicles with a long plastics tradition.
When Detroit-based GM began preparing for the sixth generation of its Corvette, which debuted this year, it seriously considered whether to continue using composites despite its 50-year tradition with polymers, Mattis said.
``It was a total business decision, looked at from a total business point of view,'' he said. ``It was a closer call than you might think.''
Aluminum is gaining new attention for low-volume vehicles thanks to a new processing system that lowers production costs, allowing the metal to compete with composites' lower tooling expenses.
The system, referred to as either ``superplastic'' or ``quick plastic,'' imitates compression molding techniques with pre-heated aluminum sheets.
Ford Motor Co. is using the alloy on its GT sports car, while GM has put it to use on a lift gate on the new Malibu Maxx.
``This is a serious competitor for [low-volume] applications,'' said David Steenkamer, a technical specialist in manufacturing systems for Dearborn, Mich.-based Ford.
At the same time, improvements to high-strength steel combined with hydroforming technology are allowing the metal to compete with lower production costs and lighter weight.
DaimlerChrysler AG and GM are switching to a powder primer coat - which simply does not work with plastics, noted Doug Denton, senior materials specialist for the Auburn Hills, Mich.-based Chrysler group.
Carmakers want to send all exterior body parts through the paint line together, treating all parts the same regardless of what they are made of, he said. While development of improved SMC nearly has eliminated paint-quality issues within traditional paint shops - which has won it praise from Ford with its liquid primer lines - that will not help with the new production.
``Chrysler has all but two or three of its plants converted to powder primers now,'' Denton said. ``This is a further barrier to the use of SMC on exterior body panels.''
But that is not to say that composites have nowhere to go.
Toyota is launching production of its 2005 Tacoma pickup using an SMC bed system molded by ThyssenKrupp Automotive AG's plastics division. It won that business based on two of composites' biggest selling points, low weight and flexibility, said Hidenori Nagaoka, manager of the material engineering department at Toyota's technical center in Ann Arbor, Mich.
The company will offer the truck with either a 60-inch bed or a 73-inch bed and offer a range of optional equipment that is easier to integrate into plastics.
``Toyota's opinion is that SMC has a cycle time that is a key to its opportunities,'' Nagaoka said.
Chrysler needed a strong structural material for the floor of its minivans when it wanted to provide ``stow-and-go'' seating.
The system allows users to drop the second and third row of seats into a specially designed bucket that also doubles as storage space when the seats are in use. Molder Collins & Aikman Corp. also had to come up with a material and design that would insulate passengers from road noise.
``I think there's probably a lot of success out there that has been subtle and not as well-recognized,'' Denton said. ``These are SRIM parts at high volume, and Collins & Aikman is molding basically the whole floor using glass-fiber preforms.''
In Europe, DaimlerChrysler's Mercedes group has started using SMC in car deck lids, taking advantage of the nonmetallic surface to route antennas to the rear of the car.
Beyond thermosets, North American automakers are beginning to embrace long-fiber-reinforced thermoplastics, which in the past were used more extensively in Europe.
Ford is using a glass-reinforced polypropylene for the running boards on its F-150 trucks and is so happy with the performance, it is seeking other applications, Steenkamer said.
Jay Batten, chief composites engineer for Delphi Corp., said the supplier has been concerned about the cycle time required for LFRT in the past, but is investigating improvements because of customer interest.
In the end, molders and resin suppliers will have to keep improving to meet customer demands, and be prepared for increased competition, Mattis said.
``I can see where the frustration is, in that you make progress and then you still don't get the impact that you'd like,'' he said. ``You just have to continue to do everything you can.''