Additive manufacturing processes need speed if the cost per part is going to drop to levels competitive with traditional machining and injection molding. Thus, additive vendors are exploring how chemistry can make processes faster. HP and Carbon both developed processes that take advantage of chemical reactions. Here are a few more recent innovations that use chemical interaction to build parts fast.
Voxeljet recently introduced a new way to additively build parts. The company calls this process HSS, for high speed sintering. This process involves depositing a fine layer of polymeric powder, such as PA12 or TPU, onto the build table, then using an inkjet print head to selectively deposit an infrared absorbing fluid onto the powder surface where sintering is desired. No further liquids are used for the printing process. The build area is then illumined with infrared light, causing the printed fluid to absorb this energy and then melt and sinter (fuse) the underlying powder. This process is repeated layer by layer until the build is complete to form functional plastic parts.
Another innovation comes from Concurrent Technologies Corporation (CTC). CTC engineers are working with an established process that is more than a century old and is currently used commercially to extract metals from ore. The Mond process is good at creating thin-wall parts with precise thickness and complex geometry on substrates of arbitrary shape and controlled temperature distribution.
CTC’s concept uses a gas (carbon monoxide) that reacts with any of 18 different metals to form a more complex gas at elevated temperatures. The metal then deposits on hotter substrates that define the shape of the finished component. This action frees up the carbon monoxide for reuse in reacting with additional metallic atoms and continuing the additive process.
Another innovation combines injection molding and 3D printing/additive manufacturing. The Orchid DLP 3D printer uses its DLP technology to create a hollow shell mold that is then injected with a plastic material or metal powder combined with a binding resin. After the material in the mold hardens, the mold is immersed in a warm bath until the shell melts away, revealing the part. The goal behind this innovation is to speed up the development of tooling.
The material used inside the shell is standard off-the-shelf material (rubber, silicone, metal or a polyurethane) that Collider makes available in cartridges. Post processing in a furnace eliminates the binder and solidifies the part.
Now, how about 3D printing in water? Researchers at the Hebrew University of Jerusalem’s Center for Nanoscience and Nanotechnology, have developed a photoinitiator for 3D printing in water.
The innovation is the use of semiconductor-metal hybrid nanoparticles (HNPs) as the photoinitiators–molecules that induce chemical reactions necessary to form solid printed material by light. Previously, such molecules were not soluble in water.
A key market for 3D printing in water is medical. This technology opens opportunities for tailored fabrication of medical devices and for printing scaffolds for tissue engineering. For example, the researchers envision personalized fabrication of joint replacements, bone plates, heart valves, artificial tendons and ligaments, and other artificial organ replacements.
This is just the beginning of additive innovation that will lead to more interesting ways to make parts fast.