Additive manufacturing methods are rapidly increasing, with approaches based on photopolymers that include some of the most prominent ways. These stereolithographic techniques provide a useful resolution balance, build speed, process control, and capital cost. Resolving speed limitations, surface roughness, and support structure requirements would provide the next major steps in advancing these technologies.
Researchers at UC Berkeley have developed a method said to be Computed Axial Lithography (CAL). This new method can volumetrically synthesize arbitrary geometries through photopolymerization to address this potential. It uses light to convert gooey liquids into complex solid objects in only a matter of minutes.
The CAL approach was described in Science’s open-access paper and had several advantages over conventional layer-based methods of printing. The method can be used to circumvent structures of support as it can print into fluids or even solids of high viscosity. CAL can also be used to print 3D structures around pre-existing solid components. CAL can be scaled to larger print volumes and is several orders of magnitude faster than layer-by-layer methods under a wider range of conditions.
A CAL 3D printer can create objects that are smoother, more flexible, and more complex than conventional 3D printers can do. It can also enclose an existing object with new materials, such as adding a handle to a metal screwdriver shaft, which current printers are struggling to do.
Most 3D printers, including other light-based techniques, create layer by layer of 3D objects. They also have trouble creating flexible objects because bendable materials may deform during the printing process, and supports are required to print objects of certain shapes, such as arches. The new printer relies on a viscous liquid that reacts to form a solid when exposed to a certain light threshold. Carefully crafted light patterns projecting onto a rotating liquid cylinder solidifies the desired form all at once.
The new printer has been inspired by the CT scans that can help doctors locate tumors and fractures inside the body. CT scans project X-rays or other types of electromagnetic radiation from various angles into the body. Analyzing the transmitted energy patterns reveals the object's geometry.