Last Updated on

March 13th, 2023 09:10 pm

What is roughness?

Surface roughness refers to the small spacing and the unevenness of small peaks and valleys on the machined surface. The distance (wave distance) between the two peaks or two troughs is very small (below 1mm), which belongs to the microscopic geometric shape error. The smaller the surface roughness, the smoother the surface
Increasing the surface roughness of NdFeB can increase the adhesive area and adhesive depth to improve the bonding force between the magnetic steel and the supporting parts, and ensure the reliability and service life of the product.


How to express surface roughness

The mean arithmetical value “Ra” in μm for roughness measurements.

Why pay attention to the roughness?

As the rare earth permanent magnet with the best comprehensive performance, NdFeB has been widely used in consumer electronics, vibration motors in smartphones, speakers, voice coil motors, etc. High-performance NdFeB magnets are used. With electronic technology, and image-sensing technology With the continuous development of technology and computer technology, the optical sensor can recognize the bad surface of the product and the recognition technology of product characteristics is quickly applied to the production line. For the convenience of NdFe The boron products are accurately identified, and the automatic assembly process has no problem with the surface roughness of NdFeB products degrees have specific requirements.

What factors affect the roughness

There are many factors affecting the magnetic roughness, the nature of the processing material itself, the processing method, the abrasive material, the cutting process, etc., the cleaning process and the electroplating process will also affect the roughness of the magnet surface.

How to improve roughness

There 4 main ways to improve roughtess.

Grinding the magnet

For ordinary magnets, it can be polished. Make the surface smoother. But for tiny magnet it cannot be ground because that i too small to process.

Make a coating

Plating helps to improve roughness. Among all coatings, Teflon has the smallest roughness and the best performance. The performance of parylene is also very good, but different parylene has different roughness. As far as commonly used coatings are concerned, the surface roughness of galvanizing is better than that of nickel plating.

New cutting process

Laser cutting is a new technology, but this technology is still unstable. 

Acid washing process

This process is suitable for all sizes of NdFeB. According to the conclusion of the study “Effect of Nitric Acid Pickling Process on Surface Roughness Ra of Sintered Nd-Fe-B Products”, the pickling process helps to improve the roughness.

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