Diamond grinding wheels are highly effective tools for grinding hard and brittle materials such as cemented carbide, glass, ceramics, and gemstones. In recent years, with the rapid development of high-speed grinding and ultra-precision grinding technologies, higher demands have been placed on grinding wheels. Ceramic and resin-bonded grinding wheels can no longer meet production needs. Metal-bonded grinding wheels, due to their high bonding strength, good formability, and long service life, have been widely used in production. Metal-bonded diamond grinding wheels are mainly divided into two types according to their manufacturing method: sintering and electroplating. In order to fully utilize the effect of superhard abrasives, since the early 1990s, a new type of grinding wheel has been developed abroad using high-temperature brazing technology, which is still in the research and development stage.
A grinding wheel is a cutting tool for grinding. It is a porous object composed of many small, hard abrasive grains bonded together by a binder. The abrasive grains directly perform the cutting work and must be sharp and possess high hardness, heat resistance, and a certain degree of toughness. Common abrasives include aluminum oxide and silicon carbide. Aluminum oxide abrasives have high hardness and good toughness, making them suitable for grinding steel. Silicon carbide abrasives have even higher hardness, are sharper, and have good thermal conductivity, but are more brittle, making them suitable for grinding cast iron and cemented carbide.
Grinding is a method of machining workpieces using a grinding wheel as a cutting tool on a grinding machine.
The characteristics of this method are.
(1) Due to the high hardness and heat resistance of the abrasive grains in the grinding wheel, grinding can process materials with very high hardness, such as hardened steel and cemented carbide.
(2) The characteristics of the grinding wheel and grinding machine determine that the grinding process system can perform uniform micro-cutting, generally ap = 0.001–0.005 mm; the grinding speed is very high, generally reaching v = 30–50 m/s; the grinding machine has good rigidity; and hydraulic transmission is used. Therefore, grinding can economically achieve high processing accuracy (IT6–IT5) and low surface roughness (Ra = 0.8–0.2 μm). Grinding is one of the main methods for precision machining of parts.
(3) Due to intense friction, the temperature in the grinding zone is very high. This can cause stress and deformation in the workpiece and even burn the workpiece surface.
Therefore, a large amount of coolant must be applied during grinding to reduce the grinding temperature. The coolant also serves to remove chips and provide lubrication.
(4) The radial force during grinding is very large. This causes elastic deformation in the machine tool-grinding wheel-workpiece system, resulting in the actual depth of cut being less than the nominal depth of cut. Therefore, when grinding is nearing completion, a finishing pass should be performed without further infeed to eliminate errors.
(5) After the abrasive grains become dull, the grinding force increases, causing the abrasive grains to fracture or break off, exposing new sharp edges. This characteristic is called "self-sharpening." Self-sharpening allows grinding to proceed normally for a certain period, but after a certain operating time, manual dressing should be performed to prevent increased grinding force from causing vibration, noise, and damage to the workpiece surface quality.