Abrasive grain size
The particle size of the abrasive
refers to the particle size of the abrasive. Abrasives can be divided into four groups of abrasive grains, abrasive powders
, fine powders and ultrafine powders according to their particle size. Among them, the grain size of the abrasive grains and the abrasive powder is represented by the number of meshes per inch of the screen length. The flag is the "#" symbol added to the upper right corner of the number of the granular number. For example, 240# means that there are 240 holes in the length of each inch of the screen. The larger the value of the grain size, the smaller the abrasive grains. The particle size numbers of the two groups of abrasives of ultrafine powder and ultrafine powder are expressed by the actual size of the particles. The mark is to add a letter "W" in front of the particle size number. Sometimes it can be folded into a mesh number. For example, W20 means that the actual size of the abrasive particles is between 20 μm and 14 μm, and the mesh number is 500#.
There are coarse, medium and fine particles in the particle size of various abrasives. The medium particle is the basic particle size in the abrasive powder and is the main factor determining the abrasive grinding ability, and it occupies a large proportion in the particle size composition. Practice has proved that the grinding powder after centrifugal sorting will have a grinding capacity of 20% higher than before sorting. The fine particles have a small grinding effect in the grinding, and the particle size is not only detrimental to the quality of the ground workpiece, but also reduces the grinding efficiency, and the amount thereof should be minimized in the particle size composition. Therefore, the abrasive particles are required to be uniform in terms of the efficiency of the grinding and the quality of the work. The abrasive grain group with particle size of 12#~80# has a large particle size and is not suitable for abrasives for grinding.
The hardness of the abrasive refers to the ability of the abrasive surface to resist local external action. The hardness of the abrasive (such as oilstone) is the firmness of the binder-bonded abrasive when subjected to external forces. It is one of the basic characteristics of abrasives. Grinding is achieved by using the difference in hardness between the abrasive and the workpiece being ground. The hardness of the abrasive is higher, and its cutting ability is stronger.
The strength of the abrasive refers to the firmness of the abrasive itself. That is, when the abrasive grain edge is still quite sharp, it can withstand the applied pressure without being broken. The abrasive grains of the poor strength are pulverized quickly, the cutting ability is low, and the service life is short. This requires that in addition to having a higher hardness, the abrasive particles should have sufficient strength for better grinding.