The particle size of abrasive refers to the size of abrasive. Abrasives are divided into four groups according to their particle size: abrasive, grinding powder, micro powder and ultra-fine powder. Among them, the particle size number of the two groups of abrasives, abrasive grain and grinding powder, is expressed by the number of meshes on each inch of screen length, and its mark is the number of particle size numbers plus the # sign at the upper right corner. For example, 240 # refers to that there are 204 holes in each inch of screen length, while the particle size 63 is the nominal size of the mesh that passes, the size 50 is the nominal size of the mesh that does not pass, and so on. The particle size numbers of the two groups of abrasives, micro powder and ultra-fine powder, are expressed by the actual size of the particles. The sign is that a letter W is added in front of the particle size number, such as W20, indicating that the actual size of the abrasive particles is between 20-14 microns.

According to different particle size numbers of abrasives, the following different sorting and measurement methods are adopted for the particle size of abrasives:

(1) The abrasive particles and powders with particle sizes of 12 # to 220 # are separated and determined by screening method.

(2) The grinding powder with particle sizes of 240 # to 280 # is separated by screening method, while the screening method and microscope analysis method are used for joint analysis. This is because the minimum mesh size of the screen mesh can only be 0.05~0.06 mm (equivalent to 240~280 mesh holes per hour). If it is smaller, the screening method will not be able to separate.

(3) The particle size of fine powder and ultra-fine powder below W40 shall be separated by who selection method (i.e. precipitation method) and determined by microscope analysis method.