The technicians in GM’s Lab developed a novel mechanism that permits the joining of multiple smaller pieces to make one larger part. Segments are temporarily connected with standard Cleco expanding fasteners while being assembled.

Highly specialised software automatically calculates the fine lattice-like structure below each part in the stereolithography(SLA) manufacturing process. The lattice support is snapped off by hand when the parts are complete.

Rapid prototype parts permit GM Aerodynamic Engineer Suzanne Cody to get actual surfaces from the designer’s math that fit on testing models with perfect contour in a very short amount of time

Traditionally, only virgin plastics were used for rapid prototyping, but GM’s technicians developed a process to recycle a portion of the excess SLS powder that is brushed off.

Rapid Prototyping Creates Roadworthy Concept Parts. EN-V bodies fabricated in 3D Rapid Prototyping Shop at GM Design

Designers and engineers from General Motors studios and technical centers around the world are able to see and touch their creations faster and at lower cost because of the digital manufacturing capabilities at the GM Design Center. Selective laser sintering (SLS) and Stereolithography (SLA) techniques allow designers to quickly and inexpensively go from computer models to one-off parts for wind-tunnel testing so more iterations can be tested in less time. Aerodynamics engineers can put a current production vehicle into the wind-tunnel and skilled trade technicians can quickly swap body parts like bumper covers, grilles, spoilers and mirrors between test runs.

Before the parts are fabricated in the rapid prototyping shop, the computer models are tested for proper airflow using state-of-the-art computational fluid dynamics software. These pre-tested parts can then be replaced much more rapidly and with better repeatability than old-style clay models can be re-sculpted. More time is spent evaluating the changes than waiting for adjustments to be made. In fact, testing capacity has doubled in the past two years.

“Long before a full-size model or vehicle is built, rapid prototyping helps to improve the accuracy of the one-third scale models that are used for early aerodynamic testing,” said Aerodynamic Development Engineer Suzanne Cody. “Air-flow through the engine compartment and underneath the car is critical to both cooling the engine and lowering drag.”

In the past, modelers would carve a rough approximation of the front structure and the engine from foam or wood to evaluate the air flow through the engine bay. GM’s 3D prototyping lab can generate a fully detailed model including the engine, transmission, brake lines, drive-shafts, exhaust system, suspension and other components under the car.

“The end result is better correlation of air-flow measurements between the model and the full-size car or truck and fewer expensive changes are needed late in the program,” said Cody. “With the design of components like cooling systems locked in earlier, fewer prototypes are needed and vehicles can go from concept to production more quickly.”

Rapid prototype parts also speed up test track and on-road evaluations. When 80 pre-production Chevrolet Volts were being built in mid-2009, several interior parts were fabricated by the RP shop and installed directly in the test cars.

“In design, we work with conceptual ideas in preproduction. Early part iteration allows us to get hands on to see what works and what doesn’t at the point where people actually touch the car,” said Checo Pacheco, a lead creative designer in the Branded Component Studio.

Some of the most public applications of RP components to date have been the EN-V personal urban mobility concepts that were featured and at lower cost than ever before.” during the 2010 Shanghai World Expo and the 2011 Consumer Electronics Show.

Three body styles were crafted for the EN-V at GM

Rapid prototype parts are an important resource for Checo Pacheco lead creative designer in GM Design’s Branded component Studio for the speed accuracy, quick part iteration and production finish flexibility they offer.

The General Motors Rapid Prototyping Lab, located deep inside the GM Design building operates around the clock providing components, intricate sub assembles and entire scale model cars from highly specialized three-dimensional rapid prototyping manufacturing equipment.complete.

Designers appreciate the many ways Stereolithography (SLA) parts can be painted, plated and trimmed out to emulate a desired production finish.

Design studios in Los Angeles; Melbourne, Australia; and Russelsheim, Germany. The RP shop in Warren fabricated the bodies and many of the components for the demonstration fleet. “3D rapid prototyping is enabling the designers and engineers at Chevrolet, Buick, GMC and Cadillac to stretch the creative envelope,” said John Green, superintendent, GM Design Fabrication Operations. “We can bring more attractive, functional and aerodynamic vehicles to market in less time"