According to the different abrasives used, bonded abrasives can be divided into ordinary abrasive bonded abrasives and superhard abrasive bonded abrasives. The former is made of ordinary abrasives such as corundum and silicon carbide, while the latter is made of super hard abrasives such as diamond and cubic boron nitride. In addition, there are some special varieties, such as sintered corundum abrasives. Ordinary abrasive consolidated abrasives are abrasives that are consolidated into a certain shape by a bond and have a certain strength. It is generally composed of abrasives, binders and pores, which are often called the three elements of consolidation abrasives. Abrasive plays a cutting role in abrasive tools. Binder is the material that consolidates loose abrasives into abrasives, which can be classified into inorganic and organic materials. Inorganic binders include ceramics, magnesite, sodium silicate, etc; Organic products include resin, rubber and shellac. The most commonly used are ceramic, resin and rubber binders. The air hole plays a role of chip holding and chip removing during grinding, and can hold coolant, which helps to dissipate grinding heat. In order to meet some special processing requirements, certain fillers, such as sulfur and paraffin, can also be impregnated in the pores to improve the performance of abrasives. This filler is also called the fourth element of abrasive tools. The items representing the characteristics of ordinary abrasive bonded abrasives include: shape, size, abrasive, particle size, hardness, structure and bond. Abrasive hardness refers to the difficulty of abrasive particles falling off from the surface of abrasive tools under external force, which reflects the strength of binder holding abrasive particles.
Particle size refers to the size of abrasive particles, which is represented by particle size number. The national standard specifies two particle sizes of abrasive and fine powder. Grain size refers to the size of abrasive particles. The particle size can be divided into two categories: abrasive and fine powder. The abrasive with a large particle size and a cylindrical grinding wheel greater than 40 μ m is called abrasive. Grading shall be carried out by screening method, and the particle size number shall be expressed by the number of holes per inch on the screen through which the abrasive particles pass. For example, the size of 60 # abrasive particles is just enough to pass the screen with 60 holes per inch of length. The abrasive with particle size less than 40 μ m is called micro powder. Grading is carried out by means of microscopic measurement. The particle size number is represented by W and the number after W, and the number after W represents the actual size of the fine powder. For example, W20 indicates that the actual size of the micro powder is 20 μ m. See Table 1 for the size of abrasive particles of various particle sizes. Table 1 Abrasive particle size and its particle size Abrasive particle particle size Particle size (um) Particle size Particle size (um) Particle size Particle size (um) Particle size Particle size (um) 14 # 1600~125070 # 250~200W4040~2816 # 1250~100080 # 200~160W2828~2020 # 1000~800100 # 160~125W2020~1424 # 800~630120 # 125~100W1414~1030 # 630~500150 # 100~80W1010~736 # 500~400180 # 80~63W77~546 # 400~315240 # 63~50W55~3.560 # 315~250280 # 50~40W3.53.5~2.5 Use range of grinding wheels with different particle sizes Note: abrasive particles coarser than 14 # and micro powders finer than W3.5 are rarely used, Not listed in the table. The choice of abrasive particle size is mainly related to the surface roughness and productivity. During rough grinding, the grinding allowance is large and the required surface roughness value is large, so the coarser abrasive shall be selected. Because the abrasive grains are coarse and the air holes are large, the grinding depth can be large, and the grinding wheel is not easy to block and heat. During fine grinding, the allowance is small and the roughness value is required to be low, so finer abrasive particles can be selected. Generally speaking, the finer the abrasive grain, the better the grinding surface roughness. Particle size No. Particle size range/μ m Applicable range Particle size range/μ m Applicable range 12-362000-1600 500-400 Rough grinding, rough grinding, cutting billet, grinding burr W40-2040-28 20-14 Fine grinding, super fine grinding, thread grinding, honing 46-80400-315 200-160 Rough grinding, semi fine grinding, fine grinding W14-1014-10 10-7 Fine grinding, fine grinding, super fine grinding Mirror grinding 100-280165-125 50-40 fine grinding, forming grinding, tool sharpening, honing W7-3.57-5 3.5-2.5 super fine grinding, mirror grinding, making abrasives, etc