What are the differences between sintered and bonded cylindrical magnets?

Hey there! As a supplier of cylindrical magnets, I've gotten tons of questions about the differences between sintered and bonded cylindrical magnets. So, I thought I'd break it down for you in this blog post.

Manufacturing Process

Let's start with how these two types of magnets are made. Sintered cylindrical magnets are created through a high - temperature and high - pressure process. First, the raw magnetic materials, like neodymium, iron, and boron for neodymium magnets, are finely ground into a powder. This powder is then pressed into the desired cylindrical shape under extremely high pressure. After that, it goes through a sintering process, which involves heating it to a very high temperature (usually around 1000 - 1100°C) in a vacuum or inert gas environment. This high - temperature treatment fuses the powder particles together, creating a dense and hard magnet.

On the other hand, bonded cylindrical magnets are made by mixing magnetic powder with a polymer binder. The binder can be something like epoxy, nylon, or rubber. Once the powder and binder are well - mixed, the mixture is either injection - molded or compression - molded into the cylindrical shape. This process doesn't require the high temperatures used in sintering, so it's a bit more flexible in terms of the shapes and sizes that can be produced.

Magnetic Properties

When it comes to magnetic strength, sintered cylindrical magnets usually take the lead. The high - temperature sintering process aligns the magnetic domains in the material very well, resulting in a very strong magnetic field. For example, sintered neodymium cylindrical magnets are known for their incredibly high energy product, which is a measure of the magnet's ability to store magnetic energy. They can have an energy product of up to 50 MGOe (Mega Gauss - Oersteds), making them suitable for applications where a strong magnetic force is required, like in electric motors and magnetic separators.

Bonded cylindrical magnets, however, have a lower magnetic strength compared to their sintered counterparts. The presence of the polymer binder dilutes the magnetic material, reducing the overall magnetic performance. Their energy product typically ranges from 2 - 12 MGOe. But don't count them out just yet! Bonded magnets have other advantages that make them useful in certain applications.

Physical Properties

Sintered cylindrical magnets are very hard and brittle. This hardness is a result of the high - temperature sintering process that fuses the particles together tightly. While this makes them durable in terms of withstanding high - temperature environments and mechanical stress to some extent, it also means they are prone to chipping and cracking if mishandled. You need to be careful when machining or handling sintered magnets to avoid damaging them.

Bonded cylindrical magnets, on the other hand, are more flexible and less brittle. The polymer binder gives them some degree of elasticity, making them less likely to break under impact. They can also be more easily machined and formed into complex shapes. This flexibility makes them a great choice for applications where the magnet needs to conform to a specific shape or where there is a risk of mechanical shock.

Temperature Resistance

Sintered cylindrical magnets generally have better temperature resistance. The high - temperature sintering process makes them more stable at elevated temperatures. For example, sintered samarium - cobalt cylindrical magnets can operate at temperatures up to 350°C without significant loss of magnetic strength. Neodymium sintered magnets can typically handle temperatures up to 80 - 200°C, depending on the grade.

Bonded cylindrical magnets have a lower temperature resistance. The polymer binder starts to degrade at relatively lower temperatures, which can cause the magnet to lose its shape and magnetic properties. Most bonded magnets have a maximum operating temperature of around 80 - 150°C, depending on the type of binder used.

Cost

Cost is always an important factor when choosing between sintered and bonded cylindrical magnets. Sintered magnets are usually more expensive. The high - temperature sintering process requires specialized equipment and a lot of energy, which drives up the production cost. Additionally, the raw materials used in sintered magnets, especially rare - earth elements like neodymium and samarium, can be quite costly.

Bonded magnets are generally more cost - effective. The manufacturing process is simpler and doesn't require the same level of high - tech equipment or energy consumption. The use of a polymer binder also reduces the amount of expensive magnetic material needed, further lowering the cost. So, if you're on a budget, bonded cylindrical magnets might be the way to go.

Applications

Sintered cylindrical magnets are widely used in high - performance applications. In the automotive industry, they are used in electric power steering systems and hybrid vehicle motors. They are also used in aerospace applications, such as in actuators and sensors. The strong magnetic field of sintered magnets makes them ideal for these applications where precision and high performance are crucial. You can find more about Cylindrical Permanent Magnet on our website.

Bonded cylindrical magnets are often used in applications where flexibility, complex shapes, and lower cost are important. They are commonly used in consumer electronics, like in speakers and headphones. Their ability to be molded into different shapes allows for more creative designs in these products. You can check out our Small Cylindrical Magnets for such applications. They are also used in magnetic toys and educational kits, where the lower magnetic strength is not a drawback.

Conclusion

In summary, sintered and bonded cylindrical magnets have their own unique characteristics. Sintered magnets offer high magnetic strength, good temperature resistance, but are more brittle and expensive. Bonded magnets, on the other hand, are more flexible, easier to machine, and more cost - effective, but have lower magnetic strength and temperature resistance.

If you're in the market for cylindrical magnets, it's important to consider your specific application requirements. Whether you need a strong magnet for a high - performance motor or a flexible magnet for a consumer product, we've got you covered. Check out our Magnet Cylindrical section on our website to see our full range of products.

If you have any questions or if you're interested in purchasing cylindrical magnets, feel free to reach out to us. We're here to help you find the perfect magnet for your needs. Let's start a conversation and see how we can work together!

References

• "Magnet Technology Handbook" by John J. Croat
• "Permanent Magnet Materials and Their Applications" by E. C. Stoner and E. P. Wohlfarth