Researchers at the Department of Energy’s Oak Ridge National Laboratory have demonstrated that permanent magnets produced by additive manufacturing can outperform bonded magnets made using traditional techniques while conserving critical materials.
Scientists fabricated isotropic, near-net-shape, neodymium-iron-boron (NdFeB) bonded magnets at DOE’s Manufacturing Demonstration Facility at ORNL using the Big Area Additive Manufacturing (BAAM) machine. The result, published in Scientific Reports, was a product with comparable or better magnetic, mechanical, and microstructural properties than bonded magnets made using traditional injection molding with the same composition.
The additive manufacturing process began with composite pellets consisting of 65 volume percent isotropic NdFeB powder and 35 percent polyamide (Nylon-12) manufactured by Magnet Applications, Inc. The pellets were melted, compounded, and extruded layer-by-layer by BAAM into desired forms.
Composite pellets are melted, compounded, and extruded layer-by-layer into desired forms. (hi-res image)
While conventional sintered magnet manufacturing may result in material waste of as much as 30 to 50 percent, additive manufacturing will simply capture and reuse those materials with nearly zero waste, said Parans Paranthaman, principal investigator and a group leader in ORNL’s Chemical Sciences Division. The project was funded by DOE’s Critical Materials Institute (CMI).
Using a process that conserves material is especially important in the manufacture of permanent magnets made with neodymium, dysprosium—rare earth elements that are mined and separated outside the United States. NdFeB magnets are the most powerful on earth, and used in everything from computer hard drives and head phones to clean energy technologies such as electric vehicles and wind turbines.
The printing process not only conserves materials but also produces complex shapes, requires no tooling and is faster than traditional injection methods, potentially resulting in a much more economic manufacturing process, Paranthaman said.
“Manufacturing is changing rapidly, and a customer may need 50 different designs for the magnets they want to use,” said ORNL researcher and co-author Ling Li. Traditional injection molding would require the expense of creating a new mold and tooling for each, but with additive manufacturing the forms can be crafted simply and quickly using computer-assisted design, she explained.
Future work will explore the printing of anisotropic, or directional, bonded magnets, which are stronger than isotropic magnets that have no preferred magnetization direction. Researchers will also examine the effect of binder type, the loading fraction of magnetic powder, and processing temperature on the magnetic and mechanical properties of printed magnets.
Alex King, Director of the Critical Materials Institute, thinks that this research has tremendous potential. “The ability to print high-strength magnets in complex shapes is a game changer for the design of efficient electric motors and generators,” he said. “It removes many of the restrictions imposed by today’s manufacturing methods.”
“This work has demonstrated the potential of additive manufacturing to be applied to the fabrication of a wide range of magnetic materials and assemblies,” said co-author John Ormerod. “Magnet Applications and many of our customers are excited to explore the commercial impact of this technology in the near future,” he stated.
A team of Lawrence Livermore National Laboratory researchers has demonstrated the 3D printing of shape-shifting structures that can fold or unfold to reshape themselves when exposed to heat or electricity. The micro-architected structures were fabricated from a conductive, environmentally responsive polymer ink developed at the Lab.
In an article published recently by the journal Scientific Reports, Lab scientists and engineers revealed a strategy for creating boxes, spirals and spheres from shape memory polymers (SMPs), bio-based “smart” materials that exhibit shape-changes when resistively heated or when exposed to the appropriate temperature.
Lab researcher Jennifer Rodriguez examines a 3D printed box that was “programmed” to fold and unfold when heated
While the approach of using responsive materials in 3D printing, often known as “4D printing,” is not new, LLNL researchers are the first to combine the process of 3D printing and subsequent folding (via origami methods) with conductive smart materials to build complex structures.
In the paper, the researchers describe creating primary shapes from an ink made from soybean oil, additional co-polymers and carbon nanofibers, and “programming” them into a temporary shape at an engineered temperature, determined by chemical composition. Then the shape-morphing effect was induced by ambient heat or by heating the material with an electrical current, which reverts the part’s temporary shape back to its original shape.
Through a direct-ink writing 3D printing process, LLNL researchers produced several types of structures, including a stent that expanded after being exposed to heat.
“It’s like baking a cake,” said lead author Jennifer Rodriguez, a postdoc in LLNL’s Materials Engineering Division. “You take the part out of the oven before it’s done and set the permanent structure of the part by folding or twisting after an initial gelling of the polymer.”
Ultimately, Rodriguez said, researchers can use the materials to create extremely complex parts.
“If we printed a part out of multiple versions of these formulations, with different transition temperatures, and run it through a heating ramp, they would expand in a segmented fashion and unpack into something much more complex,” she said.
Through a direct-ink writing 3D printing process, the team produced several types of structures — a bent conductive device that morphed to a straight device when exposed to an electric current or heat, a collapsed stent that expanded after being exposed to heat and boxes that either opened or closed when heated.
“We have these materials with 3D structures but they have extra smart properties; they can retain a memory of the previous structure,” said Lab staff scientist James Lewicki. “It opens up a whole new property set. If you can print with these polymer composites you can build things and electrically activate them to unfold. Instead of a dumb lump, you are left with this sentient, responsive material.”
Stronger, lighter, smarter materials are projected payoff
Additive manufacturing techniques featuring atomic precision could one day create materials with Legos flexibility and Terminator toughness, according to researchers at the Department of Energy’s Oak Ridge National Laboratory.
In a review paper published in ACS Nano, Olga Ovchinnikova and colleagues provide an overview of existing paths to 3-D materials, but the ultimate goal is to create and customize material at the atomic scale. Material would be assembled atom by atom, much like children can use Legos to build a car or castle brick by brick. This concept, known as directed matter, could lead to virtually perfect materials and products because many limitations of conventional manufacturing techniques would be eliminated.
“Being able to assemble matter atom by atom in 3-D will enable us to design materials that are stronger and lighter, more robust in extreme environments and provide economical solutions for energy, chemistry and informatics,” Ovchinnikova said.
Fundamentally, directed matter eliminates the need to remove unwanted material by lithography, etching or other traditional methods. These processes have served society well, researchers noted, but the next generation of materials and products require a new approach.
“For the vast majority of recorded history, material transformation was limited to objects visible to the naked eye and patterned using hand-held tools,” the researchers wrote. “We can admire the prowess of the rice grain writing, or fine engraving on a prized sword blade, but only two to three orders of magnitude separate these masterpieces from Stone Age technology.”
Now, with the ability to direct matter with atomic precision, the payoff could be quantum computers, cell phones with more data storage and longer intervals between charging, higher efficiency solar cells, and stronger and less expensive lightweight materials.
Masdar Institute Researchers Leverage 3D Printing to Fabricate Strong, Lightweight Metals and Plastics with Optimized Electrical, Thermal and Mechanical Properties
Researchers from the Masdar Institute have leveraged the unique capabilities of additive manufacturing – or 3-dimensional (3D) printing – to design strong, ultra-lightweight ‘architectured foam’ structures that have the potential to make vehicle bodies much lighter and stronger and improve water production and oil and gas operations.
The novel foams can be 3D printed with various materials such as plastics, metals, ceramics, and composite materials to enhance the thermal, electrical and mechanical properties of various engineering systems, including aerospace and automotive structural components. They can be used anywhere there is a need for very strong, lightweight and conductive materials, such as in the aerospace and defense industries, or they can be used in applications that require highly conductive or porous materials, such as the energy, water and medical industries.
“The foam structures have the potential to become a platform technology, driving innovations across key industries and markets,” said Masdar Institute’s Dr. Steve Griffiths, Vice President for Research. “This project demonstrates how Masdar Institute’s strong advanced materials research capabilities support disruptive technology-based innovations in the Institute’s core research areas of water and energy while benefiting other sectors of importance to the UAE.”
Fraunhofer researchers have developed a particulary flexible additive manufacturing method that allows them to produce bone implants, dentures, surgical tools, or microreactors in almost any conceivable design. At the Medtec medical technology tradeshow in Stuttgart, the scientists from Dresden will show their research results.
The small pharmaceutical plant next to the patient’s bed is no bigger than a two euro coin. With wires and channels that are just a few hundred micrometers wide, it constantly mixes various drugs – painkillers, blood thinners, and antibiotics – and fine-tunes them to the patient’s current health condition. A futuristic scene of modern microreaction technology that doesn’t yet exist in hospitals. The Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden is working on changing that in the near future.
Processing different materials at the same time
The researchers from Dresden are focusing on suspension-based additive manufacturing methods and combinations of them with other manufacturing techniques to create not only microreactors, but also bone implants, dentures, and surgical tools. At Medtec in Stuttgart from April 12-14, they will be presenting a technological solution for creating medical components in almost every conceivable design using additive manufacturing methods.“We have no limitations in terms of type or color of material for the target components. This allows us to process ceramics, glass, plastic, or even metal using thermoplastic 3D printing. One more advantage is that several different materials can be produced at the same time,” says Dr. Tassilo Moritz from Fraunhofer IKTS’s “Materials and Processes” business division. In the lab, the scientists have already successfully made components out of high-performance ceramics and hard metals. Now they are looking for partners to put their technology to real-world use.
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