DETROIT — Imagine a world where plastic automotive-interior suppliers no longer need steel tools or presses.
The savings would be dramatic, about one-quarter of the capital expenses now spent for injection molding equipment. And tooling costs could be cut by more than half by making molds from an inexpensive epoxy resin.
Lear Corp., one of the world's largest interior-systems suppliers, seriously is considering such a far-reaching experiment. Southfield, Mich.-based Lear will begin performing trial runs this spring using a new process the company developed in-house.
Parts will be made using a familiar technology that Lear has updated for the next millennium: vacuum forming.
``We hope to be building headliners with it by the end of the year,'' said Jack Van Ert, Lear director of advanced process development.
``We can get four times the production output per square foot than we could by compression molding the parts.''
The firm, which announced its plans March 1 at SAE '99 in Detroit, actually is developing two variations of the process. Both involve forming parts from two halves of a clamshell-shaped mold, where a formed resin sheet and a natural-fiber cover skin can be melted and bonded together when the mold is closed.
No adhesive is needed to bond the material.
One version, twin-shell vacuum molding, passes air into the mold chamber and then evacuates it to create molding pressure.
The other, hydromolding, substitutes water pressure for the air.
Lear hopes to use the process for such high-profile interior parts as headliners, door-panel substrates and the knee-bolster section of an instrument panel, Van Ert said.
Vacuum forming is used regularly for smaller interior-trim panels, said Kenneth Rusch, technical programs manager with Budd Co. Plastics Division in Troy, Mich. But the process normally is not used for larger parts that need cover skins, he said.
``It doesn't work well with complicated geometry, where you need ribs or bosses or difficult shapes,'' Rusch said. ``But all you have is a low-cost tool and no press. You don't need an expensive facility and you can get huge savings from tooling and equipment.''
Budd, a large compression molder, does not use vacuum forming for exterior body parts, Rusch said, because the process does not lend itself to structural parts or thermoset resins.
But Lear is gunning for those large interior parts. The savings can be significant and production is comparatively simple, Van Ert said. Instead of bringing in a space-gobbling compression press, small vacuum forming equipment can be hooked up easily to a 110-volt outlet.
The company borrowed the idea from the office furniture industry, which vacuum forms laminated, pre-colored film stock with plastic resin to create some office pieces.
Lear is working to gain patents for the technology and form partnerships with furniture companies, Van Ert said.
Lear also could add in-mold color to its automotive parts through vacuum forming, he said. The company's first experiments will involve headliners, a vehicle's interior roof that usually is molded from reinforced thermoplastic urethane, fiberglass or PET.
The process is a good choice for low-volume parts that do not benefit from the economy of scale of injection molding, Van Ert said. But it also has quality limitations, said Alan Sundeen, president of Weber Manufacturing Ltd. in Midland, Ontario.
Sundeen, whose firm specializes in nickel-shell tooling, said the process normally is best-suited for less-expensive parts and tools.
``It's used for low-cost tooling on fairly simple parts,'' Sundeen said. ``Most [vacuum forming] customers can get by with cheaper epoxy or wood tools. A nickel tool wouldn't be for them.''