China Neodymium And Ferrite Magnets Manufacturer & Supplier 
An absolute rotary encoder is a sensor capable of directly outputting a unique angular position value at any given moment. Since it does not require zeroing even after a power cycle, it is widely used in industrial control and robotics. This type of encoder requires magnets to function; so, what types of magnets are commonly used?
In absolute rotary encoders, the magnets used are not limited to a single type. Instead, depending on factors such as accuracy, cost, structure, and manufacturing processes, they primarily consist of the following categories of magnetic materials.
1. Bonded NdFeB
Bonded NdFeB magnetic rings are also commonly used in absolute encoders. They feature strong magnetic properties and high output signal amplitude, support high-precision multi-pole magnetization (such as 32-pole, 64-pole, or even higher), and can meet the requirements for medium-to-high-resolution angle detection.
Rotary encoder structure
2. Injection-Molded Ferrite
These can be manufactured with complex structures such as protrusions and grooves, and offer good temperature resistance and corrosion resistance. Typical applications include automotive sensors, motor speed detection, and industrial encoders.
3. Rubber Ferrite
This material has relatively weak magnetic properties but offers good flexibility and impact resistance. It is suitable for temperatures ranging from -20°C to 50°C and is relatively inexpensive.
It is important to note that in absolute rotary encoders, the “multi-pole magnetization structure” of the magnets is more critical than the material itself. Encoding rings typically employ a multi-pole structure with alternating N and S poles; the greater the number of poles, the higher the theoretical resolution. Additionally, high-end absolute encoders often utilize a multi-track ring design (concentric rings with different numbers of poles), combined with Hall, AMR, or TMR sensors, to achieve unique angular encoding.
Buy these magnets;
Robot Encoder Dual-Channel Magnetic Ring 56x38x1.1mm
Encoder single-sided multipole ferrite ring magnet 34mm x 2.5mm
Injection molded multipole ring magnets for encoders 34.1x18x3mm