WANLONG
Grinding wheel is made by sintering and pressing abrasive and binder. The binder is used to bond abrasive and substrate. The type and properties of the binder determine the strength, hardness, heat resistance and corrosion resistance of the grinding wheel. In addition, the binder also has a certain influence on the surface roughness and grinding temperature of grinding. The binder is mainly determined by its own performance.
There are many types of binders, and the most commonly used binders are as follows:
1. Vitrified binder v (old standard code A)
Vitrified binder is an inorganic binder with the most extensive application. Vitrified bond grinding tools are generally used for rough grinding, semi-finishing grinding, forming grinding with large contact area, grinding of super-hard abrasive sintered bodies, etc. Vitrified binders can be used to make grinding wheels of various particle sizes, hardness, organization, shape and size.
Its main advantages are: low price, stable performance, not affected by the dry and wet weather, temperature changes and storage time; good heat resistance, sharp cutting, high grinding efficiency, not easy to heat up and clog during grinding, small thermal expansion; good corrosion resistance; ceramic binder has a large bonding force with abrasive particles, small grinding wheel wear, can better maintain the shape of the grinding wheel, and easy to control the processing accuracy. The grinding wheel made of ceramic binder can be dry ground and can adapt to grinding with various coolants.
However, due to the high brittleness and poor elasticity of ceramic binder, it cannot withstand large lateral twisting force and impact force, so it cannot be used to manufacture thinner slice grinding wheels. In addition, due to the high friction and heat generation of ceramic binder during grinding, when the grinding wheel or grinding amount is not selected properly, it is easy to cause burns and cracks on the workpiece.
2. Resin binder B (old standard code S)
Resin binder is an organic binder. The resin binder itself has good elasticity, impact resistance, and polishing effect. The grinding wheel made of resin bond has high strength and can be used to manufacture high-speed grinding wheels with a grinding speed higher than 52m/s and very thin grinding wheels. In addition, resin abrasive tools have good self-sharpening performance and are not easy to clog; they rarely need to be dressed again after one dressing, with high grinding efficiency, low grinding roughness and low grinding temperature. Because of this series of superior properties of resin bond abrasive tools, they are widely used in super-hard abrasive tools.
Resin diamond abrasive tools are used for semi-finishing and fine grinding of cemented carbide and steel-bonded cemented carbide workpieces and some non-metallic materials. Resin cubic desalinated boron abrasive tools are mainly used for blade grinding of high-vanadium high-speed steel, semi-finishing and fine grinding of tool steel, mold steel stainless steel, and heat-resistant alloy steel workpieces.
Due to the poor bonding between the bond and the abrasive, the grinding wheel wears quickly, it is difficult to maintain the shape contour, and the bond is easy to burn at high temperature. The corrosion resistance of the resin bond is also poor, the performance is not stable enough, and it is easily corroded by alkali, so the alkali content in the coolant must be less than 1.5% during wet grinding. An overly humid environment will also affect the strength of the resin grinding wheel, so pay attention to the storage of the resin grinding wheel, and the storage time should not be too long (limited to one year).
3. Rubber bond R (old standard code X)
Rubber bond is a grinding tool made of artificial synthetic rubber or natural rubber as the main raw material, and a certain proportion of sulfur, zinc oxide and other minerals are added to the abrasive, and then vulcanized at 150℃~200℃.
The elasticity of rubber bond is greater than that of resin bond, and the strength is also high, so it can make very thin grinding wheels. Under the high temperature in the grinding area, the bond on the surface of the rubber bond grinding wheel gradually ages and becomes brittle, and the blunt abrasive grains are easy to fall off, so that the working surface of the grinding wheel is always kept with new and sharp abrasive grains, thereby reducing the possibility of workpiece burns.
At the same time, this grinding wheel has a strong polishing performance and can obtain a lower surface roughness. However, rubber bond grinding wheels have a tight structure and small pores, and cannot grind away a lot of machining allowances, so they are generally not suitable for rough machining; rubber bond grinding wheels have poor oil resistance, so oil cannot be used as a coolant during grinding.
4. Metal bond (M)
Metal bonds are divided into bronze bonds and electroplated bonds. Bronze bonds have good abrasiveness, high strength, good wear resistance, long service life, good shape retention, and can withstand large loads. However, their self-sharpening properties are poor, and they are prone to clogging and heating, making them difficult to trim.
Bronze bond diamond grinding tools are mainly used for rough and fine grinding and cutting of metal materials such as glass, ceramics, stone, concrete, semiconductor materials and superhard materials, and a small amount is used for rough grinding and forming grinding of cemented carbide and honing of various materials.
5. Electroplating process (E)
Electroplated grinding wheels are different from ordinary bond grinding wheels, and they are easy to distinguish from the appearance. The electroplating process is to attach the abrasive to the machine body (usually a steel machine body) by electrolysis. The abrasive layer is very thin, usually one or two layers. The electroplated grinding wheel is sharp, wear-resistant, and has a good shape retention. No trimming is allowed.
