The grinding wheel is composed of several parts, among which the most important component is the type of abrasive. The main abrasives are corundum, silicon carbide, diamond and cubic boron nitride（CBN）. Abrasive grinding ability and processing adaptability of workpiece materials, physical and chemical properties of workpiece materials to determine whether the specific abrasive is suitable for your workpiece, whether it is the most suitable.

The most commonly used abrasives are brown corundum (A) and white corundum (WA), followed by black silicon carbide (C) and green silicon carbide (GC), and the remaining commonly used are chromium corundum (PA), single crystal corundum (SA), microcrystalline corundum (MA), zirconium corundum (ZA).                           

Silicon carbide grinding wheel
Silicon carbide has two kinds of black silicon carbide and green silicon carbide.
* Black silicon carbide contains SiC ~ 95%. Mainly used for processing glass, stone, ceramic, refractory materials, non-ferrous metals and other low tensile strength materials.
* Green silicon carbide contains more than 97% of SiC. Used for processing hard alloy, optical glass and titanium alloy. Because of its high hardness and adhesion resistance, it is suitable for finishing and super finishing workpiece.
Compared with corundum artificial abrasive, black silicon carbide has higher hardness and greater brittleness. It is suitable for processing metal and non-metallic materials with low tensile strength, such as gray cast iron, brass, lead and other non-ferrous metals, as well as hard brittle materials such as ceramics and glass factory materials. Green silicon carbide compared with black silicon carbide, its purity, hardness, brittleness is slightly larger, suitable for processing hard and brittle materials, such as hard alloy, glass, agate, etc., is also widely used in measuring tools, cutting tools, die fine grinding and engine cylinder honing aircraft, automobiles, ships and so on.

Corundum grinding wheel
According to the different content of alumina powder and the different auxiliary materials, it is divided into brown corundum grinding wheel, chrome corundum grinding wheel and white corundum grinding wheel. Other commonly used are single crystal corundum grinding wheel, microcrystalline corundum grinding wheel, zirconium corundum grinding wheel.

Ø Brown corundum grinding wheel has high toughness and is suitable for processing metals with high tensile strength. It is mostly used for grinding workpiece. Brown corundum is suitable for grinding metals with high tensile strength, such as carbon steel, alloy steel, malleable cast iron, hard bronze, etc. This abrasive has good grinding performance and wide adaptability. It is often used for coarse grinding with large allowance. It is cheap and can be widely used.
Ø The hardness of white corundum grinding wheel is slightly higher than that of brown corundum, and the abrasive particles are easy to be broken in grinding, so it is suitable for precision grinding of high carbon steel and quenched steel.
Ø Chrome corundum grinding wheel is used for machining tools, measuring tools, instruments and threads. High quality machining surface.
Ø Single crystal corundum grinding wheel is suitable for stainless steel and other workpiece with high toughness, high hardness and easy to burn and deformation.
Ø Microcrystalline corundum grinding wheel has good form-preserving property, especially suitable for forming and cutting grinding of stainless steel, bearing steel.
Ø Zirconium corundum grinding wheel is suitable for grinding austenitic stainless steel, titanium alloy and heat resistant alloy. Good performance in heavy load grinding.

How to choose grinding wheel size in general?
With coarse-grained grinding wheel, the production efficiency is high, but the surface of the workpiece is rough. When grinding with fine-grained grinding wheel, the surface roughness of the workpiece is good, but the productivity is low. Coarse-grained grinding wheels should be selected as far as possible to ensure high grinding efficiency on the premise of meeting the roughness requirements. Generally, coarse-grained grinding wheel is used for coarse grinding, and fine-grained grinding wheel is used for fine grinding.
Selection of large hole grinding wheel
The grinding wheel with large hole has the advantages of not being blocked easily, high durability and strong cutting ability. Suitable for rough and fine grinding of soft metal, plastic, rubber, leather and other non-metallic materials. At the same time, it has the characteristics of fast heat dissipation, so in grinding some heat-sensitive materials, thin-walled workpiece and dry grinding process (such as grinding cemented carbide tools and machine guide, etc.) has a good effect.
The production scope of large hole grinding wheel is: carbide and corundum are generally selected as abrasives, such as black silicon carbide (C), green silicon carbide (GC) and white corundum (WA) are commonly used. These abrasives have high hardness, crisp and sharp, and good thermal and electrical conductivity. Abrasive particle size (36#~180#); Binder (ceramic binder); Hardness (G~M levels); Shape (flat, cup, bowl or dish, etc.); Stomatal size (~ 0.7~1.4 mm).

Basic rule of grinding wheel selection:
1) When grinding materials with high tensile strength, choose abrasives with high toughness.
2) When grinding materials with low hardness and large elongation, choose brittle abrasive.
3) When grinding materials with high hardness, choose abrasives with higher hardness.
4) Choose abrasives that are not easy to be processed for chemical reactions.
The diamond pen with good wear resistance is used in the dressing of the grinding wheel, and the appropriate cutting edge shape and installation Angle are adopted. When the dressing amount is appropriate (the longitudinal feed should be smaller), the abrasive cutting edge can obtain good contour property and reduce the surface roughness.