PT_Plastics Today

Plastics Today, September 2015

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NEW TECHNOLOGIES PLaSTICSTOday.COm GLObaL PLaSTICS REPORT 2015 11 Wacker develops silicone 3D-printing method Necessity, once again, has proven itself to be the mother of invention, with 3D print- ing playing the role of enabler. Marathon runner Maximilian Peter, who works as an engineer at Wacker Silicones (Munich, Germany), longed for an athletic shoe with shock-absorbing insoles and a per- fect fit. Holding a doctorate in chemical engineering and through his daily activities at Wacker, he quickly identified the best material for this application, silicone, and the appropriate manufacturing process, 3D printing. There was just one problem: Sili- cone parts can only be injection molded, a prohibitively expensive process for custom products, and no suitable 3D printing materials were available. The solution? A novel silicone formulation and a new approach to the 3D printing process. Peter brainstormed with engineers at Ing- enieure GmbH, a product development and prototyping bureau in Ergolding, Germany, to find a way to 3D print using silicone. "Until now, it has been impossible to print with elastomers. No suitable processes were available," says Peter. Within about a year, however, the group had developed an addi- tive process that would work with silicone. The 3D printer they created uses a glass printing bed and employs a robot that runs on a custom program. The printing head, controlled by the robot, pauses after depos- iting silicone droplets so that a UV beam can pass over the material and crosslink the molecules into an elastomer. Once vulca- nization is complete—it takes less than one second—the cycle is repeated. Ultimately, they hope to develop a system that can process 100 grams of silicone per hour. The finish is significantly smoother than 3D-printed thermoplastics, says the company. Peter and his team claim that the finished item looks almost as if it were injection molded, and for that, they credit their collaborator, silicone developer Ernst Selbertinger. Selbertinger created a silicone formula- tion that can be dosed as tiny droplets that stay where they are put. He likens the material to toothpaste: "It flows under pressure, as you squeeze it from the tube, but sits firmly on the toothbrush," explains Selbertinger. He won't disclose much else about the formulation, other than to say that it contains a platinum catalyst to enable crosslinking under UV light. Wacker anticipates far-reaching applica- tions for the technology in the automotive and medical sectors, in particular. Instead of keeping an inventory of spare silicone parts for cars, they can be printed on an as- needed basis, for example. In hospitals and clinics, implants could be custom printed, even during an operation, based on data provided by magnetic resonance imaging machines. And let's not forget one more applica- tion: The best running shoes ever. — Norbert Sparrow make the change Are these guys in your supply chain? SALES@CADENCEINC.COM CADENCEINC .COM/PLASTICS 800.252.3371 Over 50 years of molding experience with engineered plastics.

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