Printing times could also be shortened thanks to the new technique, said the researchers from the University of Southern California (USC).
As conventional 3D printers create custom objects layer-by-layer, they often need to print supports to balance the product. These supports are manually removed after printing, which requires finishing by hand and can result in shape inaccuracies or surface roughness. The materials the supports are made from often cannot be reused, so they are discarded and contribute to the growing problem of 3D-printed waste material.
Traditional 3D printing using the Fused Deposition Modelling (FDM) technique prints directly onto a static metal surface. A new prototype developed by the USC team uses a programmable, dynamically controlled surface instead. The device is made of moveable metal ‘pins’ that replace printed supports. The pins rise up as the printer progressively builds the product.
Testing has shown that the new prototype saves about 35% of materials used per object, said research leader Professor Yong Chen. “I work with biomedical doctors who 3D print using biomaterials to build tissue or organs,” he said. “A lot of the materials they use are very expensive – we're talking small bottles that cost between $500 to $1,000 each.
“For standard FDM printers, the materials cost is something like $50 per kilogram, but for bioprinting, it's more like $50 per gram. So if we can save 30% on material that would have gone into printing these supports, that is a huge cost saving for 3D printing for biomedical purposes.”
Conventional 3D printing processes using supports is also time-consuming, Chen said.
“When you're 3D printing complex shapes, half of the time you are building the parts that you need, the other half of the time you're building the supports. With this system, we're not building the supports. Therefore, in terms of printing time, we have savings of about 40%.”
The research team, also led by PhD student Yang Xu, said the prototype works by running each of its individual supports from a single motor that moves a platform. Based on the product design, the program's software tells the user where they need to add a series of metal tubes into the base of the platform, determining the height the pins rise to.
The system could be adapted for large scale manufacturing such as automotive and aerospace, Chen said. “People are already building FDM printers for large size car and ship bodies, as well as for consumer products such as furniture. As you can imagine, their building times are really long – we're talking about a whole day. So if you can save half of that, your manufacturing time could be reduced to half a day. Using our approach could bring a lot of benefits for this type of 3D printing.”
The team has applied for a patent for the new technology.
The work was co-authored by Ziqi Wang at EPFL Switzerland, previously a visiting student at USC, and Siyu Gong from USC Viterbi. It was published in Additive Manufacturing.
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