Though 3D printing has been around since the 1990s, it's one of the most buzzworthy words of the 2000s and today. And for good reason -- the ability of machines to print actual objects, rather than just sheets of paper, seems like something out of a sci-fi movie. How in the world could this be possible?
What's 3D Printing?
The most common 3D printers use additive processes, laying down successive layers of material that follow computerized directions to form a tangible object. They've reached a point where just about any object can be printed, from car parts to functioning human organs. 3D printers were once extremely expensive and meant for industrial use, but startup companies have been making affordable consumer models for a few years now.
Though the range of printable objects is massive, there's one material that has been particularly tough to print objects with: silicone.
Silicone Makes Things Difficult
If you look at the history of liquid silicone rubber, it has similar qualities to rubber, which makes it hard to use in additive processes without first melting it or layering it. In other words, think of how hard it would be to squeeze a small rubber object through a tube.
The only way to make a silicone object is to create a mold and pour silicone into it, which is known as injection molding. The process can be very costly. But here's some good news: that process may be a thing of the past, thanks to a recent development by German chemical manufacturer Wacker Chemie.
In its Interim Report for January to June 2015, Wacker claims it found a solution to using silicone material in additive processing 3D printers. And it all started with running shoes.
The Perfect Shoe
Maximilian Peter, an engineer at Wacker Chemie and an avid marathon runner, dreamed of creating a running shoe that fit perfectly and provided the perfect shock absorption. Through his research, he determined the best material to use was silicone, and 3D printing would be the best way to get the job done.
Silicone was a material known to be tricky with 3D printing, so Peter and his team set about making an entirely new approach to 3D printing -- one that would work with silicone.
The new process involves a computerized printing nozzle that prints tiny drops of silicone side-by-side. After the droplets are deposited, the nozzle pauses to allow a beam of UV light to flash. This beam fuses the droplets together, creating an elastomer. All of this happens in less than a second.
Team member Ernst Selbertinger came up with a silicone formulation that can not only be squirted out as tiny droplets but also a formulation that locks the droplets in place. He told Plastic Today the material is much like toothpaste: "It flows under pressure, as you squeeze it from the tube, but sits firmly on the toothbrush." He didn't disclose any other details.
This revolutionary system is extremely precise, producing objects with significantly smoother surfaces than objects printed with other materials. The quality is so high the objects look as though they've been injection molded.