What is the manufacturing process of disc shaped magnets?

What is the manufacturing process of disc shaped magnets?

As a supplier of Disc Shaped Magnets, I'm often asked about the intricate manufacturing process behind these remarkable products. In this blog, I'll take you through the detailed steps involved in creating disc shaped magnets, shedding light on the precision and technology that goes into their production.

Raw Material Selection

The first and most crucial step in manufacturing disc shaped magnets is the selection of high - quality raw materials. The most common types of materials used for disc magnets are neodymium, ferrite, and samarium - cobalt. Neodymium magnets are known for their extremely high magnetic strength, making them suitable for a wide range of applications, from small electronic devices to large industrial equipment. Ferrite magnets, on the other hand, are more cost - effective and have good resistance to corrosion, often used in consumer products. Samarium - cobalt magnets offer high - temperature stability and are used in specialized applications where performance in extreme conditions is required.

At our company, we source the purest metals and alloys for our disc shaped magnets. For neodymium magnets, for example, we obtain raw materials with the correct proportions of neodymium, iron, and boron. These raw materials are carefully inspected to ensure they meet our strict quality standards before moving on to the next stage of production.

Melting and Alloying

Once the raw materials are selected, they are melted together in a high - temperature furnace. This process is called alloying. For neodymium magnets, the mixture of neodymium, iron, and boron is heated to a temperature of around 1400°C. The high temperature ensures that the elements are completely melted and evenly mixed together, forming a homogeneous alloy.

During the melting and alloying process, it is essential to control the temperature and the atmosphere inside the furnace. An inert gas, such as argon, is often used to prevent oxidation of the metals. This helps to maintain the purity and quality of the alloy, which is crucial for the magnetic properties of the final product.

Powder Production

After the alloy is formed, it is processed into a fine powder. There are two main methods for producing magnet powder: the melt - spinning method and the HDDR (hydrogenation - disproportionation - desorption - recombination) method.

The melt - spinning method involves pouring the molten alloy onto a rapidly rotating copper wheel. As the alloy hits the wheel, it cools rapidly, forming thin ribbons. These ribbons are then crushed into a powder. This method is commonly used for producing high - performance neodymium magnet powders.

The HDDR method, on the other hand, uses hydrogen gas to break down the alloy into a powder. The alloy is first heated in a hydrogen atmosphere, causing it to disproportionate into a mixture of metal hydrides. Then, the mixture is heated again in a vacuum to desorb the hydrogen and recombine the metals into a fine powder.

The particle size of the magnet powder is carefully controlled, as it directly affects the magnetic properties of the final magnet. Smaller particle sizes generally result in stronger magnets.

Compacting

The magnet powder is then compacted into the desired disc shape. This is usually done using a hydraulic press. The powder is placed in a die that has the shape of a disc. Under high pressure, the powder is compressed into a solid form. The pressure applied during compacting affects the density and the magnetic orientation of the magnet.

To achieve a specific magnetic orientation, a magnetic field can be applied during the compacting process. This aligns the magnetic domains in the powder, which significantly enhances the magnetic strength of the final magnet. For example, for a disc magnet with a north - south pole alignment through its thickness, a magnetic field is applied in that direction during compacting.

Sintering

After compacting, the green (unfinished) disc magnets are sintered in a high - temperature furnace. Sintering is a process where the compacted powder particles are bonded together by heating them below their melting point. For neodymium magnets, the sintering temperature is typically around 1000 - 1100°C.

During sintering, the density of the magnet increases, and the magnetic properties are further enhanced. The sintering process must be carefully controlled, as improper sintering can lead to defects such as cracks or uneven density in the magnet. The atmosphere in the sintering furnace is also controlled, usually using an inert gas to prevent oxidation.

Machining and Finishing

Once the magnets are sintered, they may need to be machined to the exact specifications. Machining operations can include grinding, drilling, and cutting. For disc shaped magnets, grinding is often used to achieve the desired thickness and surface finish. Drilling may be required if the magnet needs to have a hole in the center, for example, for mounting purposes.

After machining, the magnets are cleaned to remove any debris or contaminants. Then, a protective coating can be applied to the surface of the magnets. Coatings are used to prevent corrosion and to improve the durability of the magnets. Common coatings for neodymium magnets include nickel, zinc, and epoxy.

Magnetization

The final step in the manufacturing process is magnetization. After the disc shaped magnets are machined and finished, they are placed in a strong magnetic field to magnetize them. The magnetic field must be strong enough to align all the magnetic domains in the magnet in the desired direction.

The magnetization process can be done using a pulse magnetizer or a direct - current magnetizer. The choice of magnetizer depends on the size and type of the magnet. Once magnetized, the disc shaped magnets are ready for inspection and packaging.

Applications of Disc Shaped Magnets

Disc shaped magnets have a wide range of applications due to their unique properties. They are commonly used in motors and generators, where their strong magnetic fields can be used to convert electrical energy into mechanical energy and vice versa. In the electronics industry, disc magnets are used in speakers, headphones, and hard drives. They are also used in magnetic separators, magnetic sensors, and various types of holding and clamping devices.

For those interested in our disc shaped magnets, we offer a variety of sizes and specifications. You can check out our 5mm Diameter Magnet for small - scale applications. Our Disc Magnets page provides an overview of our full range of disc - shaped products, and for more detailed information about our Disc Shaped Magnet, you can visit the dedicated page.

If you are in the market for high - quality disc shaped magnets for your specific application, we invite you to contact us for a detailed discussion. Our team of experts is ready to assist you in selecting the right magnets and providing you with customized solutions to meet your needs.

References

• "Permanent Magnet Materials and Their Application" by E. C. Snelling
• "Magnetism and Magnetic Materials" by D. Jiles