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So, is 3D printing magnets possible?\u00a0Sort of, but not yet at home.\u00a0<\/strong><\/p>\n Bringing the power of 3D printing\u00a0to magnet manufacturing is attracting a lot of interest. Magnets are made of critical rare earth metals, such as neodymium, which are in short supply and high demand in the current push for electric cars and alternative energy. 3D printing can help reduce overuse of this material with its ability\u00a0to create efficiently-shaped and -sized magnets without the time or expense of tooling. This also helps to quickly bring new designs to market.<\/p>\n So what\u2019s the hold-up?\u00a0A magnet seems simple. There\u2019s a north end and a south end. We even use magnets on our refrigerators.\u00a0How complicated can they be?<\/p>\n Beneath the surface, the most powerful permanent magnets have an organized granular structure that\u2019s a challenge to recreate with a 3D print head.<\/p>\n In order to understand the potential of 3D printing magnets, let\u2019s first take an in-depth look at what actually makes materials magnetic.<\/p>\n All materials have electrons. As small as they are, electrons have what is called \u201cspin\u201d. This spin\u00a0creates a tiny magnetic field\u00a0so that each electron is like a tiny magnet. In non-magnetic substances (like wood, water, or aluminum), these electrons and their tiny magnetic fields are arranged in opposing pairs,\u00a0essentially canceling each other out.<\/p>\n In\u00a0ferromagnetic materials<\/strong>, like iron, some unpaired electron spins favor being aligned so that their magnetic fields add together rather than cancel out. Interestingly, in a plain piece of unmagnetized iron, this alignment of spins and their microscopic magnetic fields spread through the entire piece of material. The result is that the material is divided into sub-millimeter magnetized regions, called magnetic domains.<\/p>\n Within each magnetic domain, all of the unpaired spins are aligned. When a piece of iron is in the unmagnetized state, these domains exist but are randomly oriented and create a net zero magnetic field. However, if exposed to a sufficiently strong magnetic field, the domains will align,\u00a0and the iron is magnetized\u00a0with a north and a south pole.<\/p>\n Only three of the elements in the periodic table are ferromagnetic at room temperature: iron, cobalt, and nickel. Practical magnets are based on these elements but are often combined with other elements, such as neodymium and samarium, to modify their properties.<\/p>\n \u201cHard\u201d ferromagnetic materials<\/strong>, or\u00a0permanent magnets<\/strong>, maintain their magnetized state, attracting materials like iron and steel regardless of surroundings and electrical current. These materials are not easy to magnetize, requiring a strong field and energy to change the direction of their magnetic domains. On the other hand, they also hold their magnetization permanently.<\/p>\n In\u00a0\u201csoft\u201d ferromagnetic materials<\/strong>, like pure iron, the magnetic domains align (and disalign) easily to an external field. This means they can be easily magnetized and demagnetized. Soft magnetic 3D filament\u00a0is\u00a0currently available,\u00a0but\u00a0because much of the material is PLA (and therefore non-magnetic),\u00a0there are\u00a0limitations<\/a>\u00a0if you are considering serious\u00a0soft magnetic applications, like inductors\u00a0or transformer cores.<\/p>\n Permanent magnets are all about direction: north and south. But before magnetization, the raw materials of magnets exhibit this same directionality, or\u00a0magnetic anisotropy<\/strong>.\u00a0This means they have a preferred direction for magnetization.<\/p>\n During the manufacturing of\u00a0anisotropic materials<\/strong>, powders of ferromagnetic material\u00a0can be pre-aligned so that the fine grains line up with the desired direction of magnetization. This alignment\u00a0can be done with a strong magnetic field or when the powder is\u00a0squeezed\u00a0with high pressure.\u00a0Once the\u00a0grains are aligned, they are locked in place before the actual magnetization step. This pre-alignment results in a stronger magnet because all of the crystals point in the preferred direction\u00a0and\u00a0contribute to the resulting magnetic field.<\/p>\n Manufacturing\u00a0isotropic magnets<\/strong> create unmagnetized bodies\u00a0with grains pointed in every direction. When it comes time to magnetize them, only a fraction of the grains can contribute. This means that the resulting magnet is weaker. However, it simplifies manufacturing, which also means that any direction of magnetization is possible.<\/p>\n Sintered magnets<\/strong>\u00a0are the gold standard for magnets of today: solid magnetic material, formed with pressure and temperature without a filler or bonding agent.\u00a0Today\u2019s most powerful neodymium magnets are\u00a0sintered anisotropic magnets<\/a>.<\/p>\n Bonded magnets<\/strong>\u00a0use nylon or epoxy to adhere the magnetic grains. The bonding process allows for more intricate designs and mass production techniques like injection molding. However, the bonding substance dilutes the density of the magnetic material and therefore the strength of the magnet.<\/p>\n While it doesn\u2019t create the strongest magnets,\u00a0bonding technology forms the basis for most of the current research in 3D printed magnets.<\/p>\n As you can probably guess,\u00a0desktop magnet 3D printing is limited to filaments composed of soft magnetic material. In other words, prints will react to magnetic fields but won\u2019t be able to produce them.<\/p>\n While other \u201cmagnetic\u201d filaments exist, perhaps the best-known is\u00a0Proto-Pasta\u2019s\u00a0Magnetic Iron PLA<\/span>.<\/p>\n With\u00a0magnets being so critical and 3D printing being such a revolution, it\u2019s no surprise that researchers are looking into how to bring the two together.<\/p>\n One of the\u00a0first publications detailing 3D printed magnets<\/a>\u00a0comes from the Vienna University of\u00a0Technology.\u00a0They proved the concept that 3D printed magnets are possible, using custom magnetic filament and a standard printer.<\/p>\n At MIT, researchers\u00a0have\u00a0combined a magnetic 3D printing ink and magnetic field<\/a>\u00a0applied during extrusion to control the magnetic directions of 3D printed regions of soft magnetic materials. The process doesn\u2019t create a magnet, but their innovative use of a field in the actual printing may point toward future advances in 3D printed magnets.<\/p>\n Oak Ridge National Labs<\/a>\u00a0(ORNL) is\u00a0using\u00a0additive manufacturing<\/a>\u00a0to work\u00a0on the problem of the\u00a0efficient use of the\u00a0critical\u00a0rare earth elements used in the manufacture of permanent magnets. Their Big Area Additive Manufacturing (BAAM) system is showcased in\u00a0a wide range of\u00a0BAAM projects<\/a>.\u00a0It has been applied in the creation of large magnets over 5\u00a0inches in diameter. What may come as a surprise is that\u00a0BAAM\u00a0doesn\u2019t use filament<\/a>. Filament melting is simply too slow to keep up with the deposition rates they need. Instead, BAAM directly extrudes pellets to create parts at high speed.<\/p>\n Originally limited to isotropic magnets, ORNL has extended their work to include a\u00a0post-printing alignment step<\/a>\u00a0for anisotropic powders. This is pushing them closer to directly competing with existing injection-molded magnets while offering the scale of BAAM and tool-less advantages of additive manufacturing.<\/p>\n Higher concentrations of magnetic material and lower concentrations of plastic binder strongly affect magnetic strength. This, along with the move to anisotropic materials, are\u00a0under development at ORNL and elsewhere.<\/p>\n What does this mean for your desktop 3D printer at home?\u00a0Will these advancements\u00a0make their way into an affordable filament? Maybe\u2026 Deposition is just one step of making a magnet, and magnets may not be a big DIY application. But, looking into the crystal ball,\u00a0these magnetic powders are nylon-coated, so maybe they\u2019ll end up in a\u00a0Multi Jet Fusion<\/a>\u00a0system, which uses just such powders.<\/p>\n Whether\u00a0created at home or in industry, powerful magnets are central to applications like\u00a0electric cars and wind generators. Bringing the power of additive manufacturing and 3D printing\u00a0to these 21st century needs only makes sense.<\/p>\nWhat Makes Material Magnetic?<\/h3>\n
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Hard vs Soft Ferromagnetic Materials<\/h3>\n
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Isotropic vs Anisotropic Magnets<\/h3>\n<\/div>\n<\/div>\n
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Sintered vs Bonded Magnets<\/h3>\n
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3D Printing Magnets at Home<\/h3>\n
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3D Printing Magnet Research<\/h3>\n
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What’s Ahead?<\/h3>\n
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