At GM, rapid 3D prototyping helps concept cars become reality faster

The issue with concept cars has always been just that — they’re concept cars. Physical manifestations of aspirations, dreams and experiments.

Not ready to roll — just ready to salivate over.

General Motors this morning gives us a peek into the three-dimensional rapid prototyping process that it says helps accelerate the creative process and reduce the time and money spent to take concepts from paper sketches to reality.

Automakers used to use clay modeling and later, molding to produce prototype parts in three dimensions. (They’d even use foam or carved wood.)

At GM’s Design Center in Michigan, engineers and designers now use selective laser sintering and stereolithography techniques to quickly turn computer models into one-off parts for wind-tunnel testing.

Why wind tunnel testing? Aerodynamics aren’t just important for drag and thus fuel efficiency, they’re also important for cooling the engine.

The new approach means technicians can quickly swap body parts (bumper covers, grilles, spoilers, side mirrors) to see how they perform in the real world. The faster the fabrication, the more quickly the team can arrive at a final design.

Here’s how the process works:

1. With computational fluid dynamics software, digital models are tested for proper airflow.
2. Parts are produced for a one-third scale model.
3. Parts are tested in the wind tunnel.
4. Part performance is evaluated relative to other options.
5. The process repeats.

With 3D prototyping, engineers can now fabricate models of an engine, transmission, brake lines, drive shafts, exhaust system and suspension. Naturally, the 3D prototyped parts are more accurate, too, allowing there to be a closer match in performance between model and production vehicle.

GM says its testing capacity has doubled in the past two years because designers spend more time evaluating changes, rather than waiting to make adjustments.

It also means the test track and road evaluations come more quickly in the process. GM says the process helped speed production for everything from the Chevrolet Volt to the EN-V urban concept car — both of which, if you’ll recall, we test drove earlier this year.