Inside the 3D-Printing Lab Behind the $340K Cadillac Celestiq

Additive manufacturing, the engineer's version of what everyone else calls 3D printing, is too slow and too expensive to mass-produce car parts, but the calculus flips for an ultra-low-volume car like the Cadillac Celestiq. With just 25 examples of the $340,000 (to start) halo car being built for the first year, GM engineers turned to additive manufacturing for more than 130 parts made from aluminum, stainless steel, and plastics including polyamide 11 and 12 (nylon), thermoplastic polyurethane, and polypropylene.

Celestiq engineers aren’t just drawing up three-dimensional CAD files and pressing Ctrl+P, though. Before graduating to production, all of the Celestiq’s 3D-printed parts passed through the Additive Industrialization Center on GM’s Warren, Michigan, tech campus. The 16,000-square-foot lab is filled with 3D printers, some the size of small sheds, that can turn powdered metals, powdered polymers, and polymer filaments into car parts, but they don’t make production components here. Instead, the AIC team validates the design and business case for a component before passing off production, usually to a supplier. “Our job is to bring in the technology, industrialize it, and move it to the point of manufacturing,” technical specialist Brennon White said.

READ MORE: Driven! Is the $340,000 Cadillac Celestiq Worth Rolls-Royce Money?

How 3D Printing Is Used in the Cadillac Celestiq

Should you ever find yourself behind the wheel of a Celestiq, you’ll see the AIC’s work on display front and center in the aluminum steering wheel trim (below). It’s the largest 3D-printed part in the car and the largest metal component GM has ever 3D-printed. It starts life as a powder so fine it can be absorbed through the skin and becomes something you can hold through a process called powder bed fusion. The “printer” deposits a thin layer of powered aluminum on a work surface and then zaps select areas with a laser, melting the particles into a thin piece of solid metal. A fresh layer of powder is then spread on top of that, and the process repeats. Layer by layer, the 3D form takes shape. The part is then finished on a mill, which exposes the voids that create four LED-backlit icons.

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Celestiq designers drew up the cabin with unusually thin B-pillars, fully exposing the seat-belt guide loop that’s normally hidden behind a piece of trim. Without a suitable product in the parts catalog, the engineering and design teams used 3D printing to create a safety-critical component that’s also a piece of stainless-steel jewelry—one that executive chief engineer Tony Roma says is strong enough to lift the three-ton Celestiq. It’s GM’s first such use of additive manufacturing for a safety component.

Elsewhere, the designers have printed intricate details in places few people will ever look. The stainless-steel anchors for the leather passenger grab handles have a smooth, polished exterior. When the handle is grabbed, the hinged anchor swings open, revealing a pattern inspired by Cadillac’s Mondrian motif and the Art Deco era (below). It’s made using metal binder jet technology, in which powdered metal is initially laid down with an adhesive compound holding it together. The bonded powder is then placed in a sintering oven and baked for 20 hours with the temperature peaking at nearly 2,500 degrees Fahrenheit, a process that shrinks the part as much as 20 percent.

The Celestiq also relies on 3D printing for countless plastic bits and pieces that will never be seen or touched by buyers, such as the polypropylene brackets behind the front and rear fascias that hold the ultrasonic parking sensors. White says that one of the Additive Industrialization Center’s core competencies is understanding when and where it makes financial sense to use these techniques.

When the Celestiq team proposed 3D-printing the plastic sides of the glove box (which are eventually wrapped in leather), AIC’s analysis initially said the business case wouldn’t pencil out. But after design engineers countered that it would take two prototype tools, not one, to complete development, the math changed. Once they had committed to printing the part, the engineers took advantage of that flexibility and fine-tuned the design with 27 revisions.

3D Printing for Mere Mortals

GM won’t be 3D-printing parts anytime soon for the half million Chevy Silverado pickups it builds every year, but the technology already has automotive uses beyond an ultra-exclusive halo car. More than 15 GM plants have at least one 3D printer on hand as tools to make tools that aid assembly. These machines use the same technology hobbyists use at home, layering melted polymer filament into plastic jigs, molds, and parts. The process is much slower than using powdered plastics, but it doesn’t require the safety precautions of handling fine particles that easily become airborne. A Stratasys F900 in a factory can take more than a week to turn filament into a part that nearly fills a 3x3x2-foot cube. For comparison, the AIC’s HP Multi Jet Fusion printer needs about 12 hours to turn powdered polymers into components that fill its smaller 15x15x11-inch working area.

The automaker has also deployed 3D printing for a few higher-volume programs. Cadillac builds some 3,000 manual-transmission CT4-V and CT5-V Blackwing sedans every year, each one with a 3D-printed shift-knob medallion, climate-control duct, and metal wiring harness bracket. And when GM needed a quick fix for a faulty spoiler seal on an SUV—with millions of dollars hanging in the balance—it turned to polymer powder fusion and cranked out 60,000 parts in just five weeks. That’s an extreme example of what’s possible with 3D printing at scale, but it gives you an idea of how technology used for today’s $340,000-and-up Cadillac could one day be common in your $40,000 Chevy.