Grinding tools are tools used for grinding, grinding, and polishing. Most of the grinding tools are artificial grinding tools made with abrasives and binders, as well as natural grinding tools directly processed from natural minerals and rocks. Grinding tools are widely used in mechanical manufacturing and other metal processing industries, as well as in grain processing, papermaking, and the processing of non-metallic materials such as ceramics, glass, stone, plastics, rubber, and wood. During the use of grinding tools, when the abrasive particles become dull, due to partial fragmentation of the abrasive particles themselves or breakage of the bonding agent, the abrasive particles may partially or completely detach from the tool. As a result, new cutting edges or sharp abrasive particles continue to appear on the working surface of the tool, allowing the tool to maintain its cutting performance for a certain period of time. The self sharpening property of grinding tools is a prominent feature compared to general cutting tools. As early as the Neolithic Age, humans began using natural grinding stones to process tools such as stone knives, axes, bone tools, horn tools, and dental tools; In 1872, ceramic grinding wheels made by combining natural abrasives with clay were introduced in the United States; Around 1900, artificial abrasives were introduced, and various grinding tools made from artificial abrasives were produced, creating conditions for the rapid development of grinding and grinding machines. Afterwards, the proportion of natural grinding tools in grinding tools gradually decreased.

Grinding tools can be classified into two types based on their raw material sources: natural grinding tools and artificial grinding tools. The only natural grinding tool commonly used in the mechanical industry is oilstone. Artificial grinding tools are classified into five categories based on their basic shape and structural characteristics: grinding wheels, grinding heads, oilstones, sand tiles (collectively referred to as bonded grinding tools), and coated grinding tools. In addition, abrasives are also traditionally classified as a type of grinding tool. Consolidation grinding tools can be divided into ordinary abrasive consolidation grinding tools and superhard abrasive consolidation grinding tools according to the different abrasives used. The former is made of ordinary abrasives such as corundum and silicon carbide, while the latter is made of superhard abrasives such as diamond and cubic boron nitride. In addition, there are some special varieties, such as sintered corundum grinding tools. Ordinary abrasive bonded grinding tool is a tool that solidifies ordinary abrasive into a certain shape and has a certain strength by a binder. Generally composed of abrasives, binders, and pores, these three parts are often referred to as the three elements of bonded grinding tools. Abrasives play a cutting role in grinding tools. Adhesive is a material that solidifies loose abrasives into grinding tools, and there are two types: inorganic and organic. Inorganic binders include ceramics, rhodochrosite, and sodium silicate; Organic materials include resin, rubber, and insect glue. The most commonly used ones are ceramic, resin, and rubber binders. Pores play a role in containing and removing debris during grinding, and can accommodate coolant, which helps dissipate grinding heat. To meet certain special processing requirements, certain fillers such as sulfur and paraffin can also be impregnated into the pores to improve the performance of the grinding tool. This filler is also known as the fourth element of grinding tools. The items that represent the characteristics of ordinary abrasive bonded grinding tools include: shape, size of abrasive, particle size, hardness, microstructure, and binder. The hardness of a grinding tool refers to the ease with which abrasive particles detach from the surface of the tool under external force, reflecting the strength of the binder holding the abrasive particles. The hardness of the grinding tool mainly depends on the amount of binder added and the density of the grinding tool. If the abrasive particles are easily detached, it indicates that the hardness of the grinding tool is low; On the contrary, it indicates high hardness. The hardness grades are generally divided into seven levels: ultra soft, soft, medium soft, medium, medium hard, hard, and ultra hard, and several sub levels can be further subdivided from these grades. The commonly used methods for determining the hardness of grinding tools include the hand cone method, mechanical cone method, Rockwell hardness tester method, and sandblasting hardness tester method.

The hardness of the grinding tool corresponds to its dynamic elastic modulus, which is beneficial for using the audio method to determine the dynamic elastic modulus of the grinding tool to represent its hardness. In grinding processing, if the material hardness of the workpiece being ground is high, a lower hardness grinding tool is generally selected; On the contrary, choose grinding tools with high hardness. Grinding tools can be roughly divided into three categories: tight, medium, and loose. Each category can be further subdivided and distinguished by organization number. The larger the organization number of the grinding tool, the smaller the volume percentage of the abrasive in the grinding tool, and the wider the gap between the abrasive particles, indicating a looser organization. On the contrary, the smaller the organization number, the tighter the organization. Loose structured grinding tools are not easily passivated during use, and generate less heat during the grinding process, which can reduce the deformation and burn of the workpiece caused by heat generation. Tight structured grinding tools are less prone to shedding abrasive particles, which helps maintain the geometric shape of the tool. The organization of grinding tools is only controlled according to the grinding tool formula during manufacturing and is generally not measured. Superhard abrasive bonded grinding tools are mainly made of diamond, cubic boron nitride, and other materials bonded with binders. Due to the high price and excellent wear resistance of diamond and cubic boron nitride, the bonded grinding tools made from them are different from ordinary bonded grinding tools. In addition to the superhard abrasive layer, there are also transition layers and substrates. The superhard abrasive layer is the part that plays a cutting role, consisting of superhard abrasive and binder. The substrate plays a supporting role in grinding and is composed of materials such as metal, electric wood, or ceramic. The transition layer is used to connect the substrate and the superhard abrasive layer, and is composed of a bonding agent, which can sometimes be omitted. Common binders include resins, metals, electroplated metals, and ceramics. The manufacturing process of bonded grinding tools includes: batching, mixing, forming, heat treatment, processing, and inspection. The manufacturing process varies depending on the binder used. Ceramic bonding agent grinding tools mainly use the pressing method. After weighing the abrasive and bonding agent according to the weight ratio of the formula, they are mixed evenly in the mixer and put into the metal mold. The grinding tool blank is formed on the press machine. The raw material is dried and then loaded into the kiln for firing, with a firing temperature generally around 1300 ℃. When using a low melting point fusion bonding agent, the firing temperature is below 1000 ℃. Accurately process according to the specified size and shape, and finally inspect the product. Resin bonded grinding tools are generally formed on a press at room temperature, and there are also hot pressing processes that use heating and pressing under heating conditions. After forming, it is hardened in a hardening furnace. When using phenolic resin as a binder, the curing temperature is 180-200 ℃. Rubber bonding agent grinding tools mainly use a roller mixing machine to mix materials, roll them into thin sheets, and then use a punching knife to cut them into shape; Some also use loose materials and put them into metal molds to form on a press machine. After molding, it is vulcanized in a vulcanization tank at a temperature of 165-180 ℃. There are two manufacturing processes for metal bond grinding tools: powder metallurgy and electroplating, mainly used for superhard abrasive bonded grinding tools. The powder metallurgy method uses bronze and other binders as binders, and after mixing, it is formed by hot pressing or pressing at room temperature, and then sintered. The electroplating method uses nickel or nickel cobalt alloy as the electroplating metal, and solidifies the abrasive on the substrate according to the electroplating process to make grinding tools. Special types of grinding tools include sintered corundum grinding tools and fiber grinding tools. Sintered corundum grinding tools are made by mixing alumina micro powder and an appropriate amount of chromium oxide, shaping them, and sintering them at around 1800 ℃. This type of grinding tool has a tight structure and high strength, mainly used for processing parts such as clocks and instruments. Fiber grinding tools are made from fiber filaments (such as nylon filaments) containing or adhered with abrasives as raw materials. They have good elasticity and are mainly used for polishing metal materials and their products.