Tel: 13556601560     E-mail:

China Courage Magnet Manufacturer

14 Years High Performance Permanent Magnet Supplier & Factory

Magnet Blog

Magnet Blog

The difference between full and semi magnetic pulleys

Permanent magnet pulley, also known as magnetic roller or dry block magnetic separator, has two magnetic system structures: semi-magnetic pulley and full magnetic pulley. They act as rotating devices for permanent magnet iron removal and can continuously separate non-magnetic and magnetic materials. Today we will analyze the difference between full magnetic and semi-magnetic permanent magnet roller.

Full magnetic roller and semi-magnetic pulley detailed difference;

1, The magnetic selection area of the full magnetic drum is larger than the semi-magnetic drum, but hung on the belt, some magnetic material is sucked to the bottom of the belt after it is too late to fall off, if it happens that the magnetic material is relatively sharp, it is easy to cut the belt.

2. Full magnetic pulleys use various materials, resulting in a simple manufacturing process. Their internal magnetic system is closely integrated with the exterior, lacking any gaps, which contributes to the relative ease of achieving a strong magnetic field. The full magnetic pulleys involves magnetic system rotates with the shell, whereas in semi-magnetic pulleys, only the shell rotates while the magnetic system remains stationary. Consequently, their operational processes differ.

3. Although the scanning area of semi-magnetic pulleys is smaller, the process itself is relatively complex. A carefully balanced gap must be maintained within the middle section to allow free cylinder rotation while ensuring a maximum of 3000Gs magnetic field strength, requiring a gap of only a few millimeters.

The picture shows a permanent magnet pulley (roller) for conveyor belt

picture shows a permanent magnet roller for conveyor belt

4. Fully magnetic drum is the magnetic system and the cylinder skin are rotating together; while the semi-magnetic drum is the magnetic system does not rotate, the cylinder skin rotates. The two processes are different.

5. Applications vary. Low speed conveyor belts can be semi-magnetic. High-speed precision equipment requires full magnetism.

6. Because a gap exists in the middle of semi-magnetic pulleys, their internal magnetic field can exceed 3000Gauss, while the external surface magnetic field can reach the same strength. In contrast, full magnetic pulleys maintain consistent magnetic field strength both internally and externally.

7. Fully magnetic pulley are excellent for materials with high magnetic properties, but may be less suitable for weakly magnetic or non-magnetic materials. Semi-magnetic pulley are suitable for processing weakly magnetic materials or in some scenarios where fine sorting is required. Since the magnetic field strength is not uniform, semi-magnetic drums are typically used in the magnetic area of the drum to collect magnetic particles and in the non-magnetic area to discharge these particles.


Fully magnetic pulley are suitable for handling highly magnetic materials and relatively simple sorting scenarios, whereas semi-magnetic drums are suitable for more complex sorting tasks, and show advantages especially when handling weakly magnetic materials.

Very relevant articles;

How to choose the right magnetic pulley?

Prev: Relationship between reed switch and magnets

Next: Introduction of magnetic rods [specification features application]