Rather than sticking with traditional plastics, industrial 3D printing is pushing technological boundaries to work with liquid metal, silicone and even glass.
For all the benefits of 3D printing and additive manufacturing, industrial use is frequently restricted to rapid prototyping rather than manufacturing due to the material and technical limitations of printing with powders. This is set to change as industrial pioneers master the art of printing with pure raw materials such as liquid metal, glass and silicone. Right now, one of the biggest challenges is perfecting the art of printing at the high temperatures required to liquify durable materials like titanium and Pyrex.
The Future of 3D Printing with Glass Looks Clear
Printing with molten glass is still in its infancy. But the technique, developed by an MIT research team in Cambridge, Massachusetts, is preparing to take a leap forward in 2017.
So far, MIT has focused on printing with basic soda-lime glass, mixing in mineral oxides to add color. The team also has experimented with chemical tempering—fusing chemicals to the surface of the glass to improve its strength. But the next step is to work with more exotic forms of glass, says research co-leader Michael Stern.
Soda-lime glass is a good starting point because it has a lower melting point than some of the high-performance glass, like borosilicate, which covers materials like Gorilla Glass and Pyrex. Working with them requires higher temperatures, but otherwise I don’t think there’s anything that would prevent you applying our process to these higher-performance types of glass.
Another approach is to meld tiny glass particles using a lower-temperature technique known as sintering. But the results are structurally weak and optically cloudy. MIT’s technique involves taking molten glass directly from a kiln and loading it into the printer.
Glass is strong, transparent and chemically inert, opening up a wide range of manufacturing possibilities. Researchers are working to scale-up the process for the architectural sector. Creating “smart glass” for the building industry, infused with sensors or other substances, is perhaps the holy grail of 3D glass printing, says fellow MIT project co-leader Chikara Inamura.
Current glass manufacturing methods either produce one-off, hand-made items or large-scale production runs. The ability to custom-print glass will open up the middle ground in terms of scale and distribution. It offers the ability to fuse functionality and design, letting the world use glass in new ways.
Printing with Metal Takes to the Skies
Buffalo, New York-based Vader Systems is already printing with liquid aluminum by heating droplets to 750° Celsius before they’re deposited by the printhead. This produces sturdier results than 3D printers which fuse together powdered metal.
The company currently uses 4043 aluminum and has begun testing with 6061 and 7075 grades, which are stronger and better-suited to welding. This leap forward will see 3D printing taken more seriously as a manufacturing tool by the likes of aerospace and defense, according to director of business development Jenae Pitts.
Working with different grades of aluminum will certainly open up new opportunities for 3D printing, plus we’re moving into bronze and other higher-temperature metals in the coming year. Theoretically we’ll be able to use any kind of raw metal.
Vader is testing different heating techniques when printing at higher temperatures and with different alloys. With some materials, it employs an argon gas shield, printing in an inert atmosphere to eliminate oxygen and other flammable gases.
Printing at temperatures beyond 900° Celsius will allow Vader to work with precious metals like gold and silver. Pitts adds that even higher temperatures enable working with stainless steel and titanium. This is of interest to the medical and dental industries, particularly as improved precision makes it practical to 3D print custom parts, including titanium hip replacements. Printing with liquid metal improves product density while decreasing costs and turnaround times.
Once we’re able to print with different combinations of liquid metals, it will present a wealth of new opportunities, for example, printing lightweight wings which are fused with an outer layer of a more exotic metal to create something which goes beyond the bounds of traditional manufacturing processes.
Silicone Comes to Grips with 3D Printing
Silicone-based 3D printing is also expanding its horizons, with Munich-based chemical group Wacker Chemie AG building on its release of the world’s first industrial 3D silicone printer.
The company is working toward supporting 3D printing for its entire standard portfolio of silicones. According to corporate communications manager Florian Degenhart, this would include the full durometer range of silicone elastomers, from soft Shore A 10 to sturdy Shore A 80, and in a range of colors.
Unlike metal and glass, silicone cannot be heated and printed as a liquid. Instead, Wacker’s technique involves vulcanizing droplets of silicone using UV light, fusing them together and hardening the silicone.
Silicones are already widely accepted in the healthcare sector due to their biocompatibility and pureness. We’re working on other printable products, from an optically clear silicone to an electrically-conductive grade silicone.
Degenhart maintains that 3D silicone printing is set to take its place in the manufacturing process, not only in aerospace and the automotive sector, but also in the lifestyle and homewares domains.
One very exciting prospect is being part of the ‘factory of the future’. Today, many warehouses are needed to store spare parts. But tomorrow, silicone 3D printing will be an integral part of the production line, and parts such as gaskets will be printed on demand.
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