LAYER BY LAYER

If you were to put a blindfold on Bart Van der Schueren and lead him through his company’s widely branching halls full of 3D printers, he would know which area he was in by the smell alone. That way he’d know which of the many printing techniques was being used there to create airplane parts, medical implants, shoe insoles, eyeglasses, lamps or prototypes—layer by layer, out of nothing.

For example, there’s the slightly pungent smell of the big stereolithography printers, which look like gigantic terrariums with flickering blue lights. And there are the warm plastic fumes of the fused deposition modeling printers and the selective laser sintering printers, which are lined up in rows like incubators. Further along are the hospital-disinfectant vapors of the Multi Jet Fusion devices, which look like oversized laser printers. Every morning the technicians take the rollboxes, inside which objects have grown overnight in successive layers of powder, out of the printers.

We were unable to find out what a metal printer smells like, because in Leuven metal 3D printing is used only for the medical sector, and that area is closed to visitors. But Van der Schueren mainly wants to direct our attention to the plastics. And we do see plastic everywhere, from the exhibits in the lobby to the building’s many delicate ceiling lamps, whose seemingly organic structures are based on mathematical formulas. “Many of our visitors are fascinated by the fact that we can print metals such as aluminum, titanium, and steel,” says Bart Van der Schueren, the Chief Technology Officer (CTO) of the Materialise company. “But our workhorse is plastic. We produce about one million items annually, and 800,000 of them are made of PA 12.”

The CTO is still bemused by the fact that the company produces so many different things from polyamide 12—prototypes as well as finished products for end consumers, medicine, and automobile and airplane construction. “Actually, this material is overqualified for many applications,” he says. “It’s a bit too robust, too stiff, too temperature-resistant. For many applications you’d be better off using polypropylene, which is cheaper. But we’ve discovered time and again that PA 12 is more practical to use for additive manufacturing because it can do so many things.”

Many aspects of additive manufacturing—the term this expert uses instead of “3D printing”—contradict conventional experience and expectations. “Normally, a company would keep pestering its materials suppliers with all kinds of wishes for better material properties,” he says. But at Materialise, almost every time the technicians calculate how much it would cost to manufacture a certain design, they find out that PA 12 will produce exactly what they need—everything from lacy lampshades to metallic-looking precision parts for automobile construction, for which the PA 12 powder is mixed with aluminum particles.

“In additive manufacturing, we don’t alter the properties of the material,” says Van der Schueren. “We give items the desired properties by creating the structure we’ve developed for them at the computer. For industry, this is a whole new approach.”

This new approach has caused a minor revolution in the field of orthopedics, for example. People who wear orthopedic insoles in their shoes know that these are expensive customized items consisting of a combination of cork and leather or various plastics, depending on the stresses they will bear. Alternatively, they are inexpensive models made from a single piece of plastic on the basis of the user’s footprint.

Materialise prints orthopedic insoles made of PA 12 that are based on 3D impressions of the user’s gait. “We analyze the user’s movements and calculate how much support he or she needs at which part of the foot,” says Van der Schueren. “Our software then designs a structure that has the right properties at every point—firmer in some places, more elastic in others. Then we print it in one piece, using one single material.” Does such an insole wear well? “Let me put it this way: We made a fairly big mistake with our business model. Our customers need to reorder their insoles much less often than we expected.”

He says that many companies still need to have someone explain to them how 3D printing can contribute to value creation. “Many companies come to us saying they want to do ‘something with 3D printing’, but they don’t know exactly what. They often have completely unrealistic expectations.” The most frequent misconception is that 3D printing can replace the traditional injection molding process in mass production. The technology will someday be advanced enough to do that, but today the additive manufacturing of many series-produced items is still more expensive than many people realize.

Value creation by means of 3D printing is different, and that’s why Materialise cooperates with each one of its customers to look for its practical applications. For instance, additive manufacturing is ideal for batch sizes that are so small that it’s not worthwhile to make injection molds and other processes such as milling would not provide the desired properties.

One example of that is flying drones, in which a fiberglass support frame provides stability. Materialise prints plastic guides in which tiny channels precisely align each of the razor-thin fibers in the right order, so that they can be glued. “Considering the batch sizes in which these drones are sold, no other process would be economically feasible,” says Van der Schueren.

3D printing also creates added value in segments where it enables the mass production of unique items. Examples of that include orthopedic insoles and eyeglass frames: “Here you can see the added value more clearly than in series-produced eyeglasses. We can calculate exactly where the lenses should be in front of your eyes and where the frame should sit on your nose so that the glasses will precisely match your skull. And we can produce the glasses in any design and color you want.”

Another example of potential value creation can be seen in the lobby: an experimental car seat for Toyota that weighs only seven kilograms—a normal seat weighs 30 kilograms—and is made entirely of PA 12. Only when you look at it up close can you see that it’s made in one piece but combines a variety of structures. A weblike body gives the seat rigidity, and small feathery structures on the surface provide flexibility.

The seat is only a prototype that shows how much weight could already be saved today in automobile construction. But before it can be series-produced a great deal of technology will have to be developed. At the moment, the technology for large components is still too expensive—and here the manufacturers and engineers have to do some rethinking.

“With injection molding, you simply multiply the cost of the material by the density by the quantity and you’ve got your costs,” says Van der Schueren. In additive manufacturing, the structures are produced in a powder bath, and there are no fixed formulas for calculating how much raw material is ultimately discarded as scrap. In addition, the energy costs increase exponentially. “Normally, if you double the size you also double the costs, but in 3D printing, doubling the size means multiplying the costs by eight,” he explains.