Delphi, GE step on the gas: tricky gas-assist molding process makes 'Super Plug' possible

It doesn't look like much, but it represents a revolution in the way automotive components are developed and assembled. Five years in the making, General Motors Corp.'s Delphi Interior and Lighting Systems' "Super Plug" door hardware module epitomizes the trends taking over the automotive industry today, from modular construction to the development of new business alliances among suppliers.

Simply put, the Super Plug combines all the disparate car-door innards - including wiring harnesses, door handle, window guidance channels, stereo speakers and electric motor - into one plastic molding that can be plopped inside a door and screwed into place with six fasteners.

In conventional doors, dozens of separate parts are installed one-at-a-time and have to be bolted, welded or riveted together. With the Super Plug, many key components are snapped into place, making assembly and repair much simpler. The module even has a molded-in carrying handle, making it easier for workers to remove it from shipping crates and place inside the door cavity.

It is a crucial high-profile product for Delphi Interior and Lighting-Systems, formerly the Inland Fisher Guide Div. Like the other divisions in GM's former Automotive Components Group, it hopes eventually to get 50% of its business outside GM.

GM's Automotive Components Group changed its name to Delphi Automotive Systems - and the name of its six divisions - in February.

"The development of the Super Plug was a critical step in providing next-generation part technology for our customers," says Barbara Sanders, director of engineering-advanced development group for Delphi. "This product represents the highest level of integration and the most comprehensive parts-consolidation effort Delphi has ever achieved in door modules."

Delphi officials say they're working with OEMs all over the world on the new concept, and there is "tremendous interest from overseas." It's already scheduled for production on a '96 1/2 and a '97 vehicle. Delphi officials won't identify the customers or say whether either is non-GM.

But Delphi officials readily admit the project couldn't have come about without the help of GE Plastics, which played a crucial role in developing the resin and the advanced gas-assist injection-molding process to make the complex plastic structure that ties all the Super Plug's components together.

"Super Plug is truly a process-material-driven product, requiring the close interaction of Delphi and our material supplier - GE Plastics - to ensure its successful implementation in a timely manner," says Ms. Sanders.

GE Plastics compounded a new Xenoy polycarbonate/polyester plastic resin specifically to make the highly complex part using the gas-assist injection molding process.

Gas-assist injection molding - which actually pumps gas into the mold with the hot plastic in order to help it fill all the nooks and crannies of the mold and form more complex shapes - was the key to developing the entire Super Plug module, says Suresh Shah, engineering manager for Delphi's Advanced Development Group. It allowed the "arms" and other complex features of the part to be produced without overly expensive tooling. "It was the piece of the puzzle that was always missing," he says.

Nevertheless, Mr. Shah adds that it's a tricky process, complicated further by the fact that the Super Plug is one of the most complex parts ever produced by the gas-assist process. "Controlling the gas is very difficult," he says. "The key is that the part has to be designed for the process."

"Through a close working relationship that provided seamless integration with Delphi, we studied everything from material specification and manufacturing techniques to design assistance and assembly ergonomics," says Mike Webster, director of GM Business Development at GE Plastics in Southfield, MI. "The Super Plug is a perfect example of the way we like to work closely with our customers to assist them in their development of applications and systems that are forward-thinking."

Engineers who worked on the project say it often was impossible to tell who worked for the GM division and who worked for GE. "We could have swapped paychecks," says one.

But such camaraderie alone doesn't guarantee a successful project. The GE/ Delphi relationship in particular shows how complicated joint-development programs can be in the '90s:

Last November in a memo leaked to the media, GM threatened to "stop all business relationships with General Electric Co." because GE was threatening to halt shipments of plastic resin unless granted an immediate price hike. The memo ordered purchasing managers not only to find other sources for resin, but for "chemical, electrical and metallic commodities" supplied by GE as well. Neither side has spoken to reporters about the confrontation, but the chairmen of the two companies reportedly wound up personally ironing out the disagreement. G. Richard Wagoner Jr., president of GM's North American Operations, called the fight "a lovers' spat," and said the two companies have "kissed and made up," but it nevertheless shows how risky some long-term development projects can be.

Officials for both companies, of course, are much more eager to talk about Super Plug's benefits.

Because it combines more than 60 parts into one, the module vastly simplifies the normally labor-intensive door-assembly role in reducing man-hours per car. Delphi officials are reluctant to talk directly about reducing labor costs, but they say total system costs are expected to be 5% to 10% less than conventional door hardware components. The module also offers numerous other benefits aside from less assembly labor. Among them:

* Less weight. The light weight plastic structure eliminates numerous metal stampings and support brackets and saves an estimated 3.3 lbs. (1.5 kg) per door.

* Higher quality. All of the module's electrical and mechanical can be tested prior to delivery or installation, guaranteeing high-quality systems will be installed on the assembly line. Delphi studies show a potential 96% reduction in rejection rates of subsystem components.

* Reduced part numbers. The integration of many components into the modular Super Plug allows for an overall reduction of part numbers in an assembly plant. Studies by Delphi show possible part number reductions of 25% compared with conventional door technology.

* Improved assembly ergonomics. The jagged, sharp edges of conventional door hardware sometimes can cut and scrape assemblers. The Super Plug's plastic construction has a clean, smooth surface. Plus, its built-in handle and light weight make it easier to maneuver on the factory floor.

* Warranty reduction. Warranty costs are expected to be reduced at least 25% because there are fewer components and they are easier to replace if there is a problem. Most conventional hardware components such as window motors and stereo speakers are welded or riveted into place, and are difficult to replace when they fail. With Super Plug, these components can be snapped in and out.

* Reduced squeaks and rattles. Fewer components and the one-piece construction of the plastic mounting structure of the module chop high-frequency vibration and rattles.

* Quieter operation. Super Plug's plastic mounting frame absorbs motor and gear noise.

The Super Plug program began in July 1990, when GE Plastics and Delphi began working closely together to develop a new door module that could integrate various door components into a complete system.

The goal of the overall project was to develop a system that could meet an OEM-specified target for mass and parts reductions, piece-cost reductions, investment savings and reduction in development time. Delphi proposed a unique application of an innovative manufacturing process - gas-injection molding - for the hardware module. At the same time, GE Plastics began working on material development, custom compounding a new PC/ Polyester, 30% glass-fiber blend material specifically for the Super Plug application. Advanced finite element analysis, mold filling analysis and other computer-simulation programs - including the use of high-tech neural networks - were used to ensure processability.

Gas-assist injection molding was particularly attractive because it can produce lightweight parts with excellent stiffness and dimensional stability. Using the GE Plastics Polymer Processing Development Center in Pittsfield, MA, the Super Plug team demonstrated that the new production process would be feasible in high-production applications. The development efforts have led to numerous patents. The part now can be produced in a cycle time of only 80 seconds.

Production startup is scheduled for December 1995 at Delphi's Columbus, OH, operations. Both GE and Delphi have high hopes for Super Plug in the future, but Delphi stresses that it is only the beginning of its effort to further modularize and simplify interior component systems. It's also eyeing numerous other applications for gas-assist injection molding, such as instrument panel structural parts.

What happens if the Super Plug really takes off? Delphi says it's ready. The process for the Super Plug molding is highly automated, and it's already one of the largest injection molders in the world. "Capacity will not be a problem," says one engineer confidently.