An unique polymer established at Oak Ridge National Laboratory strengthens sand for additive manufacturing applications. The principle stems from inkjet printing, however instead of using ink, the printer head jets out a liquid polymer to bind a powdered product, such as sand, building up a 3D design layer by layer. The binding polymer is what provides the printed sand its strength.
Silica sand is a cheap, readily available product that has actually been getting interest in vehicle and aerospace sectors for developing composite parts. Silica sand is appealing for tooling because it does not change dimensions when heated up and due to the fact that it provides an unique advantage in washable tooling.
The binder jet printing process is more affordable and faster than other 3D-printing methods used by market and makes it possible to develop 3D structures from a variety of powdered products, providing benefits in expense and scalability. The concept originates from inkjet printing, but instead of utilizing ink, the printer head jets out a liquid polymer to bind a powdered product, such as sand, developing a 3D design layer by layer. The binding polymer is what offers the printed sand its strength.
The team used polymer expertise to customize a polyethyleneimine, or PEI, binder that doubled the strength of sand parts compared with standard binders.
Parts printed through binder jetting are initially permeable when eliminated from the print bed. They can be enhanced by infiltrating the design with an extra super-glue material called cyanoacrylate that fills in the gaps. This 2nd step offered an eight-fold strength increase on top of the primary step, making a polymer sand composite stronger than any other and any recognized building products, including masonry.
Oak Ridge National Laboratory scientist Tomonori Saito reveals a 3D-printed sandcastle at the DOE Manufacturing Demonstration Facility at ORNL. Credit: Carlos Jones/ORNL, U.S. Dept. of Energy
” Few polymers are fit to function as a binder for this application. We were looking for specific properties, such as solubility, that would offer us the best result. Our key finding remained in the special molecular structure of our PEI binder that makes it reactive with cyanoacrylate to accomplish exceptional strength,” said ORNLs Tomonori Saito, a lead scientist on the task.
Parts formed with conventional binders are made denser with infiltrate materials, such as incredibly glue, but none have actually reached near to the efficiency of the PEI binder. The PEI binders remarkable strength comes from the method the polymer reacts to bond with cyanoacrylate during curing.
One possible application for the super-strength sand is to advance tooling for composites manufacturing.
Silica sand is a low-cost, easily offered material that has been gaining interest in automotive and aerospace sectors for producing composite parts. Light-weight products, such as carbon fiber or fiberglass, are twisted around 3D-printed sand cores, or “tools,” and treated with heat. Silica sand is appealing for tooling since it does not change dimensions when warmed and due to the fact that it offers an unique advantage in washable tooling. In composite applications, using a water-soluble binder to form sand tools is substantial because it makes it possible for a simple washout action with faucet water to remove the sand, leaving a hollow composite form..
” To guarantee accuracy in tooling parts, you need a product that does not alter shape throughout the procedure, which is why silica sand has actually been assuring. The challenge has actually been to conquer structural weakness in sand parts,” stated Dustin Gilmer, a University of Tennessee Bredesen Center student and the research studys lead author.
Present sand casting molds and cores have actually limited industrial use since industrial methods, such as washout tooling, use heat and pressure that can cause sand parts to break or stop working on the first try. More powerful sand parts are required to support manufacturing at a big scale and make it possible for rapid part production.
” Our high-strength polymer sand composite raises the complexity of parts that can be made with binder jetting techniques, enabling more complex geometries, and expands applications for manufacturing, tooling, and building,” stated Gilmer.
The novel binder won a 2019 R&D 100 Award and has been licensed by market partner ExOne for research.
Reference “Additive manufacturing of strong silica sand structures enabled by polyethyleneimine binder” by Dustin B. Gilmer, Lu Han, Michelle L. Lehmann, Derek H. Siddel, Guang Yang, Azhad U. Chowdhury, Benjamin Doughty, Amy M. Elliott and Tomonori Saito, 26 August 2021, Nature Communications.DOI: 10.1038/ s41467-021-25463-0.
The work was sponsored by the DOEs Office of Energy Efficiency and Renewable Energy and utilized resources supported by DOEs Office of Science.
A novel polymer established at Oak Ridge National Laboratory strengthens sand for additive production applications. A 6.5 centimeter 3D-printed sand bridge, shown here, held 300 times its own weight. Credit: Dustin Gilmer/University of Tennessee, Knoxville
Researchers at the Department of Energys Oak Ridge National Laboratory designed a novel polymer to reinforce and bind silica sand for binder jet additive production, a 3D-printing technique utilized by markets for prototyping and part production.
The printable polymer enables sand structures with elaborate geometries and extraordinary strength– and is also water soluble.
The research study, published in Nature Communications, demonstrates a 3D-printed sand bridge that at 6.5 centimeters can hold 300 times its own weight, a task comparable to 12 Empire State Buildings resting on the Brooklyn Bridge.