Guide
How rare earth magnets are made (sintered NdFeB and SmCo)
A rare earth magnet is made by melting rare earth metal with iron and boron into an alloy, grinding the alloy to a fine powder, pressing the powder in a magnetic field and sintering it into a solid block that is then machined, coated and magnetized. Sintered neodymium-iron-boron (NdFeB) magnets are the strongest type and about 93% of the NdFeB market (DOE, 2022).
Five US plants are listed as making sintered magnets, from Vulcan Elements' small line to MP Materials' Independence plant in Texas, and several larger ones are being built. Samarium cobalt magnets, which Arnold Magnetic Technologies fabricates in Rochester, New York, use no dysprosium or terbium.
Verified through Oct 1, 2026
At a glance
- Main types
- Sintered NdFeB, bonded NdFeB and samarium cobalt
- Process
- Alloy, powder, press, sinter, machine, coat, magnetize
- Largest loss
- Machining, depending on the final shape (DOE)
- Heavy rare earths
- Dysprosium or terbium for hot-running grades
- Next guide
- Rare earth recycling in the US
- Sintered share of NdFeB magnets
- 93%Department of Energy, 2022
- Rare earth by weight
- 30%In a sintered magnet; 69% iron, 1% boron (DOE)
- Sintering temperature
- 1,000 to 1,100 °CDepartment of Energy
- US plants listed as operating
- 5Sintered NdFeB, from pilot to commercial scale
How are rare earth magnets made?
Rare earth magnets are made by powder metallurgy: melt and strip cast the alloy, break it up with hydrogen, jet mill it to a fine powder, press the powder in a magnetic field, sinter the block at 1,000 to 1,100 °C, then machine, coat and magnetize it. Machining causes the largest material loss.
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Melt and strip cast the alloy
NdPr metal, iron, boron and any dysprosium or terbium are melted by induction and poured onto a cooled rotating cylinder, which makes a strip with a very fine grain structure.
Output Alloy strips
In the US
- Plant operating: MP Materials strip casting at Independence
- Plant operating: USA Rare Earth strip casting at Stillwater
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Break it up with hydrogen
Hydrogen decrepitation, an optional step, reduces the grain size of the strip further before milling.
Output A finer, brittle alloy
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Jet mill to a fine powder
The alloy is ground to particles under 10 microns. The shape of the grains sets the microstructure that defines the magnet's performance. The powder can ignite in air.
Output Fine alloy powder
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Press in a magnetic field
The powder is aligned by a magnetic field and pressed into a block, so the grains point the same way.
Output A pressed block
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Sinter
Heating to 1,000 to 1,100 °C fuses the powder into a dense solid block.
Output A sintered block
In the US
- Plant operating: MP Materials Independence
- Plant operating: eVAC Magnetics Sumter
- Plant operating: USA Rare Earth Stillwater
- Plant operating: Noveon Magnetics San Marcos
- Plant operating: Vulcan Elements Research Triangle Park
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Machine to shape
Blocks are cut and ground to the finished shape. This step causes the largest material loss, depending on the size and shape, and the swarf is recycled at the plant.
Output Shaped, unmagnetized magnets
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Coat
A nickel-copper-nickel coating about 12 microns thick, the most common, protects the magnet from corrosion by water vapor and air.
Output Coated magnets
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Magnetize
After plating, the magnet is magnetized in a very strong field, which aligns the magnetization of its grains.
Output A finished magnet
Marker: Plant operating
Sources: the Department of Energy supply chain assessment for the steps, yields and coating, and MP Materials' 10-K for 2025 for the order of steps at Independence. Which plant uses which equipment is mostly not published.
What are sintered NdFeB, bonded NdFeB and samarium cobalt magnets?
Sintered NdFeB magnets are pressed and fused from alloy powder and are the strongest. Bonded NdFeB magnets hold powder in a resin and suit complex shapes. Samarium cobalt magnets resist heat better, where weight does not matter, and use no dysprosium or terbium. Sintered NdFeB is about 93% of the NdFeB market.
| Type | How it is made | Strengths and limits | US makers |
|---|---|---|---|
| Sintered NdFeB | Alloy powder pressed in a magnetic field and sintered; about 30% rare earth, 69% iron, 1% boron. | The highest energy product, which allows smaller, lighter motors. Needs dysprosium or terbium to keep strength above about 120 °C. Used in electric vehicle traction motors and direct-drive wind generators. | MP Materials, eVAC Magnetics, USA Rare Earth, Noveon Magnetics and Vulcan Elements. |
| Bonded NdFeB | Magnetic powder held in a plastic resin. | Suits complex shapes, but has a lower energy product and is brittle, so direct-drive generators and traction motors have relied on sintered magnets. | None profiled in this directory. |
| Samarium cobalt (SmCo) | Made from samarium and cobalt alloys. | More resistant to demagnetization at high temperature than NdFeB, so it suits hot, weight-insensitive uses such as aerospace and defense. Uses no dysprosium or terbium, but samarium is one of the seven elements China has licensed since Apr 2025. | Arnold Magnetic Technologies fabricates SmCo magnets and assemblies in Rochester, New York; its US sintering capacity is not stated. Electron Energy Corporation is listed in the directory without a profile. |
Share and properties are from the Department of Energy supply chain assessment (Feb 2022). See also US producers of samarium.
How much dysprosium and terbium does a magnet need?
Dysprosium and terbium make a magnet resist heat, and the amount rises with the grade's operating temperature: under 0.5% dysprosium for an 80 °C grade, 4.2% for a 150 °C grade and 8.5% to 11% for the 200 and 220 °C grades used in electric vehicle traction motors. Makers reduce the amount with grain boundary diffusion.
| Grade suffix | Maximum operating temperature | Dysprosium (weight %) | Neodymium and praseodymium (weight %) | Example uses |
|---|---|---|---|---|
| None | 80 °C | Under 0.5% | 29.5% | Toys, games, advertising |
| M | 100 °C | 1.4% | 28.6% | Hard disk drives, MRI machines, sensors, refrigeration |
| H | 120 °C | 2.8% | 27.2% | Gauges, clutches, magnetic separation |
| SH | 150 °C | 4.2% | 25.8% | Wind generators, e-bikes, industrial motors, general automotive |
| UH | 180 °C | 6.5% | 24.5% | Commercial and industrial generators |
| EH and AH | 200 and 220 °C | 8.5% to 11% | 19% to 21.5% | Hybrid and electric traction drives, high-temperature motors and generators |
Contents are approximate and from the Department of Energy supply chain assessment, which assumes 30% total rare earth. Grain boundary diffusion and the dual-alloy process, which mixes NdPr metal with ferrodysprosium, can reduce dysprosium below these levels. DOE puts 1 to 2 kg of magnet in a typical electric vehicle motor and 2.7 to 3.2 t per megawatt in a direct-drive wind turbine.
Which US plants make rare earth magnets, and how much can they make?
Five US plants are listed as making sintered magnets: MP Materials at Independence, eVAC Magnetics at Sumter, USA Rare Earth at Stillwater, Noveon at San Marcos and Vulcan Elements at Research Triangle Park. Larger plants are being built or planned. The table gives each company's stated capacity, which is a nameplate or target, not output.
| Plant | What it makes | Stated capacity | Status |
|---|---|---|---|
| IndependenceFort Worth, Texas | Sintered NdFeB; first magnets on commercial equipment in Dec 2025. | A projected 3,000 t/yr (10-K: MP committed to expand the plant to this level). Commercial shipments to General Motors expected in Q4 2026. | Plant operating |
| 10X campusNorthlake, Texas | Sintered NdFeB. | About 7,000 t/yr; commissioning from 2028. | Plant building |
| SumterSouth Carolina | Sintered NdFeB for automotive and defense stockpile use. | About 2,000 t/yr nameplate (VAC); trade press reports it was built for 4,000 t/yr. Commercial production since fall 2025. | Plant operating |
| StillwaterOklahoma | Sintered NdFeB, with strip casting and metal. | 600 t/yr run rate expected by Q4 2026. Phase 1a commissioned in Mar 2026. | Plant operating |
| Blacksburg campusSouth Carolina | Magnets, strip casting, metal and alloy. | 6,400 t/yr of magnets planned; commissioning in 2028. | Plant building |
| San Marcos plantTexas | Sintered NdFeB, partly from recycled feedstock. | Scaling beyond 2,000 t/yr (company, Jan 2026). Current output is not published. | Plant operating |
| Research Triangle ParkNorth Carolina | Sintered NdFeB. | About 10 t/yr (Oct 2025). | Plant operating |
| Benson campusNorth Carolina | Magnets and metal. | 10,000 t/yr targeted; significant output by 2027 (company). | Plant planned |
| Dallas-Fort Worth hubTexas | Magnets made from recycled magnet powder. | About 941 t/yr of magnets planned; commissioning targeted for mid-2027. | Plant planned |
| Rochester siteNew York | Samarium cobalt magnets and assemblies. | Not stated; its newly commissioned Thailand plant is outside the US. | Plant operating |
See the magnet manufacturers list for every company, and the map for locations. Capacity totals will be tracked on the capacity tracker.
Why did the US lose magnet making, and what has changed?
The Department of Energy found that US magnet makers closed because they could not compete with China, that Japanese companies held most NdFeB patents and that magnet powder is hard to ship, so alloy and powder are made beside the magnet plant. Since then, guaranteed demand has arrived: a Pentagon offtake and a defense sourcing rule from Jan 1, 2027.
- Competition Chinese scale Several companies made NdFeB magnets in the US and shut down because they could not compete with China. In 2019 about 160 Chinese producers made magnets, ten of them above 5,000 t a year (DOE, citing Adamas).
- Patents Japan held the filings Of 1,413 NdFeB patent applications filed from 2001 to 2021, 60.5% were first filed in Japan, 9.7% in China and 5.7% in the US (DOE).
- Logistics Powder is hard to ship Magnet powder is under 10 microns and can ignite, so alloy and powder are made close to the magnet plant (DOE). A magnet maker needs metal supply next door.
- Demand now Buyers with guarantees The Department of War has agreed to take all 10X magnet output for 10 years, and a defense sourcing rule bars covered magnets from Jan 1, 2027. See the Pentagon deal and DFARS explainers.
The DFARS rule is explained on the DFARS 2027 rule page.
Which US companies make rare earth magnets?
Each company page carries its plant, stated capacity, customers and sources.
- MP MaterialsIndependence now, 10X from 2028
- USA Rare EarthStillwater now, Blacksburg planned
- eVAC MagneticsSumter, South Carolina, with an Energy Fuels deal pending
- Noveon MagneticsSan Marcos, with recycled feedstock
- Vulcan ElementsA small line now, a 10,000 t/yr campus planned
- HyProMag USAMagnets from recycled powder, planned in Texas
- Arnold Magnetic TechnologiesSamarium cobalt magnets in New York
- Magnet manufacturersEvery company at this step
- US producers of NdPrThe main magnet oxide and metal
- US producers of samariumThe element for samarium cobalt magnets
Questions about rare earth magnets
What is a sintered NdFeB magnet?
It is a magnet pressed from neodymium-iron-boron alloy powder in a magnetic field and fused at 1,000 to 1,100 °C. It is about 30% rare earth, 69% iron and 1% boron by weight, and it is the strongest commercial permanent magnet type.
Why are rare earth magnets used in electric vehicles and wind turbines?
NdFeB magnets allow smaller, lighter and more efficient motors and generators. The Department of Energy puts 1 to 2 kg of magnet in a typical electric vehicle motor and 2.7 to 3.2 t per megawatt in a direct-drive wind turbine.
Who makes rare earth magnets in the United States?
MP Materials, eVAC Magnetics, USA Rare Earth, Noveon Magnetics and Vulcan Elements make sintered NdFeB magnets, and Arnold Magnetic Technologies fabricates samarium cobalt magnets. Larger plants are being built by MP Materials, USA Rare Earth and Vulcan Elements.
Why does a magnet need dysprosium or terbium?
Neodymium magnets lose strength when hot. Adding dysprosium or terbium keeps them magnetized at higher temperatures, from 4.2% dysprosium for a 150 °C grade to 8.5% to 11% for the 200 and 220 °C grades used in traction motors.
Where does the largest loss of material happen in magnet making?
In machining. Sintered blocks are cut and ground to shape before coating, and the loss depends on the final size and shape. Swarf from machining is usually recycled at the plant that makes it.
What makes a magnet comply with the defense sourcing rule?
From Jan 1, 2027 the DFARS clause bars covered magnets and metals mined, refined, separated, melted or produced in China, Russia, Iran or North Korea, with waivers that need a mitigation plan. See the DFARS explainer for the text.
Sources and verification
Each profile lists its sources, a confidence grade and a verification date. Order of authority: official records (SEC filings, agency documents), company documents and technical reports, research papers, then independent press. Syndicated copies and reference works are labeled and are never the only source for a number. Company-reported figures are labeled as such, and non-binding deals are labeled "letter of intent" or "conditional".
- Department of Energy: Rare Earth Permanent Magnets, Supply Chain Deep Dive Assessment (Feb 2022) Official record
- OSTI review, Minerals Engineering 249 (Kashyap et al., 2026) Research paper
- MP Materials 10-K for 2025 (SEC) Official record
- VAC: opening ceremony for Sumter (Jul 2026) Company document
- USA Rare Earth Q2 2026 results (SEC) Official record
- Noveon: Series C announcement Company document
- North Carolina Commerce: Vulcan Elements selects Johnston County (Nov 2025) Official record
- Mkango: HyProMag USA provides a positive update to valuation Company document
- Arnold: who we are Company document
Tags show what kind of source each link is. How sources are ranked
Guides
Which other guides are there?
Ten guides explain each step from mine to magnet, why the US is behind and how to read the technical reports behind each project in this directory.
- The chain Mine to magnet supply chain The five steps from ore to magnet, with every profiled US company at its step.
- The chain How rare earths are mined Open pits, underground mines, coal and mineral sands, and how ore becomes a concentrate.
- The chain How rare earths are separated Solvent extraction, RapidSX and chromatography, and the US plants that use each.
- The chain From oxide to metal and alloy Molten-salt electrolysis and metallothermic reduction, and who makes metal in the US.
- The chain Rare earth recycling in the US Hydrogen processing, mechanical recovery and chemistry, and why volumes are still small.
- Why the US is behind Why the US cannot process rare earths Capacity against demand, and five obstacles with the evidence for each.
- Reading the reports Types of US rare earth deposits Carbonatite, granite, clay, coal and sands, with every US project mapped to a type.
- Reading the reports How to read a project A stage ladder from exploration to production, with what each study proves and what it does not.
- Reading the reports How to read resource estimates TREO, grade, JORC, NI 43-101 and S-K 1300, with a calculator and a worked example.
- Hub All rare earth guides The five steps from mine to magnet and a reading order for the ten guides.