Selection of super abrasive bonding agents

The commonly used binders for diamond abrasives and cubic boron nitride abrasives are resin binders, ceramic binders, metal binders and electroplating binders. Metal binders include bronze binders, cast iron binders and cast iron short fiber binders. Their performance and application range are different, and they are ranked as follows according to bonding ability and wear resistance.

① Resin binder (code B)

It uses thermoplastic phenolic resin as the main binder material, and some use epoxy resin and polyimide resin as the main materials, adding a certain amount of fillers, such as chromium oxide, iron oxide, zinc oxide, copper powder, graphite, corundum abrasive, silicon carbide abrasive, etc., and fully mixing with superhard abrasives at a certain concentration, and then heating and pressurizing in the mold. Among superhard abrasives, the proportion of resin binders is about more than half.

The bonding strength of resin bond to abrasive is weak, so it has good self-sharpening during grinding, is not easy to clog, has high grinding efficiency, small grinding force, low grinding temperature, and the bond itself has a certain elasticity, so it has a certain polishing effect, and the quality of the processed surface is good, so the resin bond superhard abrasives are widely used. It is mainly used in occasions requiring high grinding efficiency and low surface roughness. Its disadvantage is poor wear resistance, large wear of the abrasive, and is not suitable for heavy-load grinding. Resin diamond grinding wheels are often used for semi-finishing and fine grinding of cemented carbide and non-metallic materials. Resin cubic boron nitride abrasives are mainly used for semi-finishing and fine grinding of high-vanadium high-speed steel, tool steel, stainless steel, heat-resistant alloys and other materials.

② Ceramic bond (code V)

The wear resistance and bonding ability of ceramic bond superhard abrasives are better than those of resin bond superhard abrasives. They are sharp and have high grinding efficiency. They are not easy to heat up and clog during grinding, have small thermal expansion, are easy to control processing accuracy, and are easier to trim. Generally used for rough grinding, semi-finishing grinding and forming grinding with large contact surface. Its disadvantage is that the grinding surface roughness value is large, manufacturing is difficult, and the application of ceramic bond CBN grinding wheel in ball screw, guide rail, gear, bearing, crankshaft, camshaft, titanium alloy grinding is expanding.

③ Metal bond (code M)

Including bronze, cast iron and other bonds.

Bronze bond has high strength, good wear resistance, less wear, long tool life, good shape retention, low grinding cost, can withstand large loads, but poor self-sharpening, easy to clog, heat, and difficult to repair. Bronze bond diamond grinding tool is mainly used for rough and fine grinding and various processes of non-metallic hard and brittle materials such as glass, ceramics, stone, concrete, semiconductor materials, etc. Bronze bond cubic boron nitride grinding tool is mostly used for honing alloy steel workpiece materials, with significant effect.

In order to improve the self-sharpening of bronze bond super-hard abrasives, some adopt the method of adding tin content to reduce the copper content; some add a certain amount of ceramics to the bronze bond and sinter them together to increase the brittleness of some bonds. This bond is also called metal ceramic bond. A certain amount of materials with good conductivity, such as silver powder, is added to the bronze bond, which is specially used for electrolytic grinding. In addition to silver, some bronze bonds also add chemical synthetics such as polytetrafluoroethylene to prevent grinding chips from adhering to super-hard abrasives to improve the grinding effect.

④ Electroplated metal bond

It is made of metal nickel and silver as materials, and 80#~W40 grain size super-hard abrasives are electroplated on the metal substrate in a single layer or multiple layers by electroplating. The electroplating process of the domestic trial-produced 200m/s electroplated CBN ultra-high-speed grinding wheel is: preparation of substrate and abrasive, preparation of plating solution, coarse sand and electroplating (pre-plating and thickening), and post-plating treatment. The electroplating solution is prepared by adding Watt nickel as the base solution and a solution containing cobalt ions.