What is the production process of flat square magnets?

As a supplier of Flat Square Magnets, I am often asked about the production process behind these versatile magnetic products. In this blog post, I will take you through the detailed steps involved in manufacturing flat square magnets, from raw materials to the final finished product.

Raw Material Selection

The first step in the production of flat square magnets is the careful selection of raw materials. The most common type of flat square magnets we produce are made from neodymium, iron, and boron (NdFeB). Neodymium is a rare - earth element that provides the high magnetic strength required for many applications. Iron is abundant and contributes to the overall structure of the magnet, while boron helps to improve the magnetic properties and stability.

We source our raw materials from reliable suppliers who adhere to strict quality control standards. The purity of the neodymium, iron, and boron is crucial as even small impurities can significantly affect the performance of the final magnet. Once the raw materials are received, they are carefully inspected to ensure they meet our specifications.

Melting and Alloying

After the raw materials are selected, they are melted together in a vacuum induction furnace. The vacuum environment is essential as it prevents oxidation of the metals during the melting process. The furnace heats the raw materials to extremely high temperatures, typically around 1600 - 1700 degrees Celsius, until they form a homogeneous alloy.

During the melting process, precise control of the temperature and composition is maintained. This is achieved through advanced monitoring systems that continuously measure the temperature and chemical composition of the alloy. Once the alloy has reached the desired composition and temperature, it is poured into a mold to form a cast ingot.

Powder Production

The next step is to convert the cast ingot into a fine powder. This is done through a process called hydrogen decrepitation (HD). In this process, the ingot is exposed to hydrogen gas, which causes it to break down into a coarse powder. The powder is then further refined through a jet - milling process.

Jet - milling uses high - pressure gas to accelerate the powder particles and cause them to collide with each other, reducing their size to a very fine powder with a particle size of around 3 - 5 micrometers. The fine powder is crucial as it allows for better alignment of the magnetic domains during the subsequent steps, resulting in a stronger magnet.

Pressing

Once the powder is ready, it is pressed into the desired flat square shape. The powder is placed into a die cavity that has the exact dimensions of the final magnet. A high - pressure hydraulic press is then used to compress the powder under a pressure of around 150 - 200 MPa.

During the pressing process, a magnetic field is applied to align the magnetic domains of the powder particles. This alignment is critical as it determines the direction and strength of the magnetic field in the final magnet. The pressed magnet, also known as a green compact, has a relatively low density and is still fragile at this stage.

Sintering

The green compact is then sintered in a high - temperature furnace. Sintering is a process where the compact is heated to a temperature below its melting point, typically around 1050 - 1150 degrees Celsius. During sintering, the powder particles bond together, increasing the density and strength of the magnet.

The sintering process is carried out in a controlled atmosphere, usually a vacuum or an inert gas such as argon, to prevent oxidation. The heating and cooling rates during sintering are carefully controlled to ensure uniform shrinkage and to avoid cracking or warping of the magnet. After sintering, the magnet has reached its final density and most of its magnetic properties are developed.

Machining

After sintering, the magnet may need to be machined to achieve the precise dimensions and surface finish required by the customer. Common machining operations include grinding, cutting, and drilling.

Grinding is used to achieve a smooth surface finish and to ensure the magnet has the correct thickness and flatness. Cutting is used to separate the magnet into individual pieces if multiple magnets are produced in a single block. Drilling can be performed to create holes in the magnet, which is useful for applications such as mounting. For example, our Square Magnet with Hole is produced using this drilling process.

Surface Treatment

To protect the magnet from corrosion and to improve its appearance, a surface treatment is applied. The most common surface treatments for neodymium magnets are nickel - copper - nickel plating, zinc plating, and epoxy coating.

Nickel - copper - nickel plating provides excellent corrosion resistance and a shiny appearance. Zinc plating is a more cost - effective option that also offers good corrosion protection. Epoxy coating is often used for applications where a smooth and non - conductive surface is required. The surface treatment process involves cleaning the magnet to remove any contaminants, followed by the application of the coating material using electroplating or spraying techniques.

Quality Control

Throughout the production process, strict quality control measures are implemented. At each stage, samples are taken and tested to ensure that the magnets meet the required specifications.

Magnetic properties such as magnetic field strength, coercivity, and remanence are measured using specialized equipment. Physical properties such as dimensions, surface finish, and density are also inspected. Any magnets that do not meet the quality standards are rejected and recycled back into the production process.

Final Inspection and Packaging

Before the magnets are shipped to the customer, a final inspection is carried out. This includes a visual inspection to check for any surface defects, as well as a final verification of the magnetic and physical properties.

Once the magnets pass the final inspection, they are carefully packaged to prevent damage during transportation. They are usually placed in plastic bags or boxes and cushioned with foam or other protective materials.

Conclusion

The production process of flat square magnets is a complex and highly technical process that requires precise control at every step. From the selection of raw materials to the final packaging, each stage plays a crucial role in determining the quality and performance of the magnets.

At our company, we are committed to producing high - quality flat square magnets that meet the diverse needs of our customers. Whether you need Square Shaped Magnet for industrial applications or Tiny Square Magnets for consumer products, we have the expertise and facilities to deliver.

If you are interested in purchasing flat square magnets or have any questions about our products, please feel free to contact us for a detailed discussion. We look forward to working with you to meet your specific requirements.

References

• Handbook of Magnetic Materials, edited by K. H. J. Buschow
• "Magnetism and Magnetic Materials" by David Jiles