In most cases, friction materials rub against various metals. It is generally believed that under friction conditions, materials with a friction coefficient greater than 0.2 are called friction materials.
1. According to its friction characteristics, the material is divided into low friction coefficient materials and high friction coefficient materials. Low coefficient of friction materials, also known as friction reduction materials or lubricating materials, are used to reduce power loss in mechanical motion, reduce wear on mechanical components and extend service life. Materials with a high coefficient of friction are also called friction materials (called friction materials).
According to the working function, it can be divided into two main categories of friction materials: transmission and brake. For example, the clutch plates of a transmission transmit the power generated by the engine to the drive wheels through the assembly and disengagement of the clutch friction surfaces in the clutch assembly, so that the vehicle begins to walk. Brake pads (divided into discs and drum pads), which are connected to the brake discs (drums) by the vehicle's brake mechanism to slow down or stop the moving vehicle.
2. According to the shape of the product, it can be divided into brake pads (disc type, drum type), brake belt, brake pad, clutch plate, and isotropic friction pad. The discs are flat, the drums are curved. Brake shoes (train brake pads, oil rigs) are a curved product, but it is much thicker than ordinary curved brake pads and ranges from 25 to 30 mm. Brake belts are commonly used in agricultural and construction machinery and are soft friction materials. Clutch plates are usually ring-shaped items. Heterogeneous friction plates are mainly used in various construction machinery, such as friction presses, electric hoists, etc.
3. According to the material of the product, it can be divided into two categories: asbestos friction materials and non-asbestos friction materials.
A. Asbestos friction materials are divided into the following categories: a, asbestos fiber friction materials, also known as asbestos velvet friction materials. Production: various brake pads, clutch pads, train synthetic brake pads, asbestos velvet rubber belts and other b, asbestos linear friction materials. Production: wound clutch plate, chopped asbestos wire friction materials, etc., asbestos fabric friction materials. Production: manufacturing laminated boring machine brake pads, brake belts, clutch panels and other d, asbestos woven friction materials. Production: Manufacture of oil-impregnated or resin-impregnated brake belts. Oil rig brakes, etc. B. Non-asbestos friction materials are divided into the following categories: one, semi-metallic friction materials. Disc brake pads for cars and heavy vehicles. The composition of the material usually contains about 30% to 50% ferrous metals (e.g. steel fiber, reduced iron powder, iron foam powder). Therefore, semi-metallic friction materials are proposed. This is the first asbestos-free material to be replaced with asbestos. Its characteristics: good heat resistance, high power absorption per unit area, large thermal conductivity, can be applied to high-speed, heavy-duty operation of automobile braking conditions. However, it has the disadvantages of large braking noise, angle cracking, and so on.
B. NAO friction materials. Broadly speaking, it refers to non-asbestos-non-steel fiber friction materials, but discs also contain small amounts of steel fibers. The base material in NAO friction materials is in most cases a mixture of two or more fibers (inorganic fibers with a small amount of organic fibers). Therefore, NAO friction material is a non-asbestos mixed fiber friction material. Generally, the brake pad is a short-cut fiber friction block, and the clutch plate is a continuous fiber friction plate.
C. Powder metallurgy friction materials. Also known as sintered friction materials, iron-based, copper-based powder materials are passed, molded and mixed and sintered at high temperatures. Suitable for braking and transmission conditions at higher temperatures. Such as: aircraft, trucks, heavy construction machinery brake and transmission. Advantages: long service life; Disadvantages: high product price, brake noise, heavy and brittle, large wear d, carbon fiber friction material. A friction material made of carbon fiber as a reinforcing material. Carbon fiber has high modulus, thermal conductivity and heat resistance. Carbon fiber friction materials are the best of all types of friction materials. Carbon fiber friction plates have high absorption capacity and light specific gravity per unit area. It is particularly suitable for the production of aircraft brake pads. Brake pads from some foreign high-end cars are also used. Due to its high price, its application range is limited and the output is small. In the composition of carbon fiber friction materials, in addition to carbon fiber, graphite and carbon compounds are used. The organic binders in the components are also carbonized, so carbon fiber friction materials are also called carbon-carbon friction materials or carbon-based friction materials.
