On the campus of the General Motors Technical Center in Warren, Michigan, is a 9,000 ft² laboratory where they’re building a wide variety of prototypes—from bumpers to spoilers and almost everything in between—with selective laser sintering (SLS) and stereolithography (SLA), technology that’s commonly referred to as “rapid prototyping” (RP) and which is becoming known as “additive manufacturing” (AM). The GM RP lab features 18 machines from 3D Systems (3dsystems.com), which makes it one of the places with the greatest concentration of AM equipment outside of companies that specialize in the process (typically known as “service bureaus”).
Why is GM using it? Because of two big drivers in auto today: Reducing product development cost and time-to-market.
The lab is manned by 15 specialists who work three shifts, six days a week, taking part orders from GM design centers all over the world to crank out some 20,000 unique parts a year. Parts are built from one of two additive technologies: SLS, where a laser fuses layers of powdered material together, or SLA, where a laser cures liquid polymer, layer by layer. Parts are built within hours and then express shipped to their destination, allowing designers and engineers to spend more time evaluating changes and less time waiting for parts compared to conventional prototyping methods.
“The return on investment has been significant, especially when you figure in the elimination of tooling,” says Dave Bolognino, GM Director of Design Fabrication Operations. He uses a register vent as an example. “If you look at the complexity in that part alone, back in the old days, somebody would have to carve that or make it in clay just to get a look at it. Now we can go right to the machine and get a functional part much, much quicker than you could ever get an aesthetic part.”
Bolognino says the automaker has been using additive technology for the past 20 years. But back in the early days, he says, the speed, materials and accuracy limited the technology to just vehicle mockups. Now, it has advanced to a point where bumpers, grilles, spoilers, and mirrors—parts that would be difficult to quickly make any other way—can be accurately built.
The only limitation is the work envelope of the machines. The lab’s largest machine features a work envelope of 500 x 500 x 750-mm, so in order to build bigger parts, sections are produced, then assembled.