General Motors

Stereolithography Provides a Symphony of Benefits

At General Motors, the world's largest user of stereolithography, what began as a grass roots push has spread like wildfire throughout the corporation. Penetrating most of GM's many divisions, rapid prototyping is becoming a necessary tool in the critical race to be first to market.

The drive to be first to market accelerates. Executives demand higher profit margins. Consumer needs and wants change almost overnight. General Motors, like auto makers the world over, faces the daily challenge of decreasing product cycle time, increasing profits and meeting the needs of consumers before they're even expressed.

Dr. Susan Smyth and Steve Willis, of GM's Manufacturing Center, which is the Rapid Prototyping Center of Expertise for NAO (North American Operations), tackle this challenge with vigor. Through the use of rapid prototyping (RP) methods like stereolithography (SL), they have found a tool to ignite GM's success - reduce the time it takes to prototype a vehicle.

Road Blocks
Time has never been a luxury for auto manufacturers. Within all vehicle programs, a driving need is to have many prototype components ready at the right time. "The room for error is small," states Smyth. "We don't want to create a bottleneck because some of the components are ready, but are waiting for additional components to be finished. We can't wait!" With RP technologies like SL, they don't have to.

Throughout the company, the goal is the same - produce high quality, innovative parts at lower cost in less time. At GM, more and more often, the means to achieving this goal is RP. Successes spread like wildfire. "When designers and engineers see how it helps achieve our goal, they become good repeat customers for RP projects," remarks Tom Greaves, Advanced Manufacturing Engineer with Delphi Interior and Lighting Systems (a components division of GM).

Tuning Up
At Delco Electronics, GM's automotive electronics subsidiary, the engineers, given a chance to showcase their talents, orchestrated a masterpiece: the Maestro project.

Designed to harmoniously blend an advanced Audio System, a hands-free cellular phone, Global Positioning System (GPS) navigation, Radio Data System (RDS) information, and climate control into a completely integrated driver control system, the Maestro was to be a technological tour de force.

With many uniquely-shaped push-buttons, two active-matrix LCD screens and a local area network allowing for future expansion, the Maestro had only one possible sour note: time.

Delco Electronics realized that only 6 months remained before Convergence '94, the world's premiere automotive electronics conference. Held only once every two years, Convergence was the critical launching point for Maestro.

Stereolithography Sets the Tempo
Working together with Modern Engineering, and engineering service company located in Michigan, Delco Electronics developed the first renderings and concept drawings for the Maestro project. It soon became apparent that the team was going to have to buy time at the front end of the project in order to have sufficient time to integrate the complex electronics and still make the deadline for Convergence. Having an instrument panel with its myriad of working push buttons early in the design cycle was critical. Unfortunately, the very large number of buttons meant a correspondingly large number of rubber molds, with all the delays associated with the conventional molding process.

From the stylist's concepts, Modern Engineering manually machined models of each button face for customer design approval. Once approved, the machined models were laser-scanned, generating the necessary CAD data for the creation of SL models. The CAD data, consisting of the backside geometry of the buttons, the housing and its mechanical circuit board requirements, was then delivered to GM's NAO RP Center. The final prototype buttons needed to be accurate enough to ensure proper fit and function, as well as be translucent, so that they could be backlit.

Orchestrating Results
Working with an SLA 500, John Bolognino, Supervisor at GM's NAO Center of Expertise for RP, modified the original button design, flattening the underside of the button face to eliminate "stair-stepping" on the inside surface. With this modification, the buttons would not betray their SL origin, even when backlit.

Typically, machined models would have been created from the CAD data and then used to generate rubber molds. From those molds would come the individual parts necessary for benching each unique button. However, the SL models supplied by GM were so accurate they could be finished, painted and installed in the actual prototype vehicle, eliminating the need for rubber molds altogether. According to Brian Davert, Project Manager for Modern Engineering, "The SL process allowed for continuous design development of a functional part, delivered within hours of design direction."

The result? In less than four months, Delco Electronics had a complete, functional instrument panel, with all 108 buttons built in SL directly from CAD data. "By using SL, we bought ourselves two months to complete the electrical work," says Nancy Edenborough, the Advanced Development Engineer responsible for the Maestro project. "This was a crucial project for us, a showcase. It had to be done in time for Convergence. SL allowed us to accomplish that."

Launching Maestro at Convergence '94 solidified Delco Electronics' position as an automotive technology leader and a first-class supplier to the world wide automotive industry. Fully functional, and installed in a stock high-end European luxury automobile, Maestro provides an integrated control system completely in sync with today's automotive consumer.

Sharing the Wealth
Designers and engineers from dozens of divisions throughout GM share stories like these at their Annual Internal RP Convergence. Hosted in 1991 by Smyth and Greaves, the conference has met with amazing success. Because participation is restricted to GM employees, engineers and designers are allowed to share real numbers and statistics which makes for solid, hard-hitting presentations.

With a goal of educating and informing, the conference continues to thrive. Over the last 5 years, as GM designers and engineers come to recognize the significance of RP, the attendance has grown. Distinctively diverse application stories are now shared by multiple divisions within GM.

Getting Physical
As GM goes through each new model year and each new design program, more and more uses for RP appear. As designers and engineers communicate with each other, offering suggestions and solutions, more work flows into the RP Departments - much of that work geared toward enhancing future communications.

Three-dimensional models establish a synergy in product development. They eliminate some of the communication barriers between designers and engineers, helping everyone speak the same language. More than half the time, upon evaluation of a physical part, designers find areas to improve. Things that couldn't possibly be seen on a two-dimensional CAD screen. SL reduces costs significantly by allowing designers to perform multiple iterations, perfecting the part before a nickel is spent on tooling.

Additionally, physical models act as a communication tool between GM and their vendors, minimizing confusion regarding specifications and allowing vendors to make suggestions regarding better methods of manufacturing. Supplier quotes are more accurate, often less expensive, and guesswork eliminated.

RP methods like SL have proven themselves time and time again at GM. From power train prototypes to interior lighting systems and from inter-departmental communications to vendor quotes. Greaves sums it up - "Nothing takes the place of having a physical part to work with."