Instead of building up plastic filament layers for layers, a new method for 3-D printing lifts complex shapes from a liquid vessel up to 100 times faster than conventional 3 -D printing processes, University of Michigan researchers have shown.
3-D printing can change the game for relatively small manufacturing jobs and produce fewer than 1
"With conventional approaches, it can't be achieved unless you have hundreds of machines," said Timothy Scott, chemistry engineering associate professor led the development of the new 3-D printing method with Mark Burns, TC Chang Professor of Engineering at UM . Their method solidifies the liquid resin by means of two candles to control where the resin hardens and where it remains liquid. This allows the team to solidify the resin in more sophisticated patterns. They can make a 3-D base relief in a single shot rather than in a series 1D line or 2-D cross section. Their print demonstrations include a lattice, a toy boat and a block M.
"It's one of the first real 3-D printers ever made," says Burns, a professor of chemistry and biomedical technology.
But the real 3-D method is not just stunt. It was necessary to overcome the limitations of previous efforts for VAT printing. Unnamed: The heart tends to solidify in the window as the light shines through and stops the print job just as it begins. By creating a relatively large region where no solidification occurs, thicker resins potentially with reinforcement of powder additive cans can be used to produce more durable articles. The method also has the structural integrity of filament 3-D printing, since the objects have weak points at the interface between the layers.
"You can get much tougher, much more durable materials," says Scott.
An earlier solution to the problem of solidification-on-window was a window that allows oxygen to pass. The acid penetrates into the resin and stops the solidification near the window and leaves a film of liquid which causes the freshly pressed surface to be removed. However, since this gap is only approximately thick as a piece of transparent tape, the resin must be very flowing to float sufficiently fast in the small gap between the newly solidified object and the window when the portion is occupied. This has limited VAT printing on small custom products that will be treated relatively carefully, such as dental units and shoe soles. By replacing the oxygen with a second light to stop the solidification, the Michigan team can produce a much larger gap between the object and the window microfeter's thickening resin flowing thousands of times faster.
The key to success is the chemistry of the resin. In conventional systems, there is only one reaction. A photo activator cures the resin wherever the light shines. In the Michigan system, there is also a photoinhibitor corresponding to another wavelength.
Instead of just checking solidification in a 2-D plane, the current Michigan team can pattern the two types of light to cure the resin at virtually any 3-D location near the illumination window.
UM has filed three patent applications to protect the many inventive aspects of the approach, and Scott is preparing to start a startup.  A paper describing this research will be published in Science Advances entitled "Rapid, continuous additive manufacturing by volumetric polymerization inhibition patterning."
Volumetric 3-D printing is based on the need for speed
"Fast, Continuous Additive Production by Volumetric Polymerization Inhibition Patrating" Science Advances (2019). advances.sciencemag.org/content/5/M/eaau8723
3-D Printing 100 times faster with light (2019, January 11)
January 11, 2019
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