neodymium segment magnets

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Neodymium segment magnets are one of the types of magnets that have a wide range of commercial applications. For example, we often need large neodymium magnet rings. However, the cost of producing an individual piece can be high. Luckily, we can alternatively use smaller arc-shaped magnets to build bigger ring magnets. 

Neodymium arc magnets, or neodymium segment magnets, have a curved or arched shape. We often use them in applications where you need a strong magnetic field within a specific and limited space – usually in an iron housing.  

Neodymium segment magnets have particularly wide industrial applications. They include motors, generators, voice coil motors, wind turbines, torque couplings, and other applications. 


Features of neodymium segment magnets

Neodymium segment magnets are smaller segments of a bigger neodymium ring magnet or neodymium disc magnet. Users usually choose this solution for its better cost-effectiveness than ordering individual disc magnets or ring magnets. 

Meanwhile, it is also possible to obtain a higher magnetism using multiple smaller segments to build a bigger ring or disc, which is not possible for a complete piece to offer.   


Arc neodymium magnets have many applications, and two of the most common applications include electrical motors and Halbach arrays. 

Neodymium Segment Magnets

Arc magnets for electrical motors and generators 

We often use arc magnets to build electric motors and electricity generators. A high-quality motor or generator needs high Coercivity (HCJ), High Energy (BHmax), and high working temperature. Usually, arc neodymium magnets are the best choice. 

The electric motors and generators have arc-shaped magnets inside with opposite magnetic orientations but the same quantity, arranged in compartments to form a ring. 



Arc magnets for Halbach arrays 

A Halbach array is a magnetic assembly of permanent magnets that augments the magnetic field on one side while reducing the field on the other side to near zero.  

There are 2 types of arrays – the linear array and the ring array. Typically, the ring array is an assembly using arc magnets with different magnetic directions. 


Dimensional identifications

It’s not easy to tell the dimensions of neodymium arc magnets clearly with a simple formula. Their shapes can have different angles, curves, etc.  

Therefore, we always recommend sending us a technical sketch for a FREE quote. 


Available dimensions

 As mentioned above, neodymium arc magnets can have many different shapes. So, it’s not easy to tell what maximum dimensions are available. The values below are based on simplified results. Please talk to Osenc if your design is close to the maximum dimensions. 


Available sizes for neodymium arc magnets 

Outer diameters: 1.5 – 300 mm (1/16 – 11 13/16 inches) 

Height: 0.3 – 120 mm (1/64 – 4 ¾ inches) 

Magnetic direction: 100mm (3 15/16 inches) 


These are the possible limits that Osenc can offer.  

If your designs are close to the biggest or smallest values, we need to confirm details case by case. 


The smallest neodymium arc magnets 

Outer diameter 1.5mm × height 0.3mm (1/16 x 1/64 inches) 



Neodymium magnets have different grades, ranging from N35 to N55, and they also have high-temperature designs for special applications. 

You can refer to our introduction to neodymium magnet grades. It will be helpful for you to determine which grade is the most appropriate for you. 

Generally speaking, the neodymium arc magnets work in closed environments that have a lot of heat and energy due to high-speed running. So, it’d be better to choose the high-temperature grades. 


Magnetization directions

Disc neodymium magnets have 2 common magnetization directions. They are the axial and radial magnetization directions. 

Meanwhile, they still have 2 additional possible magnetization directions, though they are not commonly applied.  



Neodymium magnets are sensitive to the working environment. The humidity and even other corrosive elements can cause them to corrode quickly. 

To improve the durability of neodymium magnets, we will need to apply a layer or even multiple layers of coatings on their surfaces. Meanwhile, this will also make the magnets more resistant to scratches and other types of damage.  

Osenc can offer custom neodymium magnets with several different types of coatings. They include nickel, zinc, epoxy, etc. Each of them has its own unique properties and benefits.  

Please refer to this page to pick the most appropriate coating for your magnets. 


Regular arc shapes 

We have another name for the arc magnets – the tile magnets. This is because their shape is similar to the tile. And usually, we categorize neodymium magnets of this shape as regular arc magnets. 

Twisted arc shapes 

This is one of the most common custom magnets. They have a curved shape that minimizes detent and enhances motors’ performance. But they are very difficult to process regarding manufacturing techniques. Proudly, Osenc is one of the who can. 


3). Large arc magnets 

Besides arc magnets of the regular dimensions, there can be large arc neodymium magnets as well. We can obtain such designs by using post-processing techniques for block magnets or disc magnets. They are achievable through those metalworking techniques.  

Generally speaking, we can offer large arc magnets smaller than the maximum dimensions of the block magnet 250 x 100 x 40 mm and the disc magnet diameter 300 mm. 


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