I. Introduction
Friction material is a kind of component material used in power machinery and relying on friction to achieve braking and transmission functions. Any mechanical equipment and all kinds of moving vehicles must have a brake or transmission device, and the friction material is a key component on this brake or transmission device, which enables the mechanical equipment and various motor vehicles to work safely and reliably .
According to different working environments, friction materials can be divided into dry friction materials and wet friction materials. As the name implies, dry friction materials are generally used in dry environments; wet friction materials refer to friction materials that are in a lubricated state in a sealed environment. Early friction devices mostly used dry friction materials. In recent years, due to their superior performance in reliability, safety and life, wet friction materials have been rapidly developed and are widely used in automobiles, construction machinery, agricultural machinery and various It is used in the braking, clutch and gearbox of various industrial machinery.
At present, there are various classifications of wet friction materials, including paper-based friction materials, sintered metal-based friction materials, carbon-based friction materials, graphite-based friction materials, and rubber-based friction materials. Each friction material has its own functions and advantages. Based on factors such as comprehensive production methods, production costs and service life, paper-based friction materials occupy a relatively large advantage and have been widely used. With the continuous improvement of its formula and production process, modern paper-based friction materials have been widely used in various types of vehicles and construction machinery such as wet braking, clutch and gearbox applications.
This article mainly introduces the basic properties and applications of paper-based friction materials.
2. Basic properties of paper-based friction materials
Paper-based friction material is a material with a network-like porous structure, which is composed of fibers and fillers to form a framework, and is a porous structure formed by resin bonding. This porous structure can store lubricating oil, the paper-based friction material and the friction couple are compressed and deformed when they work, and the lubricating oil inside the material is squeezed to the surface to form a lubricating film; when separated, the paper-based friction material will rebound and recover The original pores and suck the lubricant back into the pores.
Effects of different lubricants
Due to the porosity of the paper base, the paper-based friction material is greatly affected by the oil. Paper-based friction materials are widely used in various machines, and the oils used are also different, so the friction performance of the same friction material in different lubricants will be quite different.
The following is the friction coefficient characteristics of Carlisle (Carlisle Brake and Friction Material) under the same test conditions in different oil 名媛直播 (a certain type of gear oil and hydraulic oil, not representative).
Figure 1 Dynamic friction coefficient of friction material in gear oil
Figure 2 Dynamic friction coefficient of friction material in hydraulic oil
It can be seen from the above figure that the friction coefficient characteristics of the same friction material in different oil 名媛直播 are different. Paper-based friction materials have a strong dependence on oil 名媛直播, even in the same oil 名媛直播, due to various needs, various additives are added to the oil 名媛直播, such as dispersants, anti-corrosion agents, viscosity index improvers, etc. , Will also have a certain effect on the characteristics of friction materials.
Effects of different densities
Due to the porosity of the friction material, different densities, ie different porosities, also have a greater impact on friction performance. Friction materials with different densities affect the thermal conductivity of friction materials on the one hand and the thermal fatigue and durability of the friction materials; on the other hand, they affect the instantaneous bonding process of the friction pair and the lubrication state of the friction surface, which in turn affect the change of the friction coefficient Trend and its stability, so density is an important performance index of paper-based friction materials.
The following is the friction coefficient and durability characteristics of Carlisle (Carlisle Brake and Friction Materials) under the same test conditions and with different density of friction materials under the same test conditions.
The density of paper-based friction materials gradually increases from Type 2 to Type 6.
Figure 3 Dynamic friction coefficient of friction materials with different densities
Figure 4 The wear rate of friction materials with different densities
Figures 3 and 4 intuitively reflect the dynamic friction coefficient and wear rate of friction materials with different densities after 30,000 cycles. It can be seen that the higher the density, the lower the wear rate, but it will affect the friction coefficient; the lower the density, the larger the friction coefficient can be achieved, but the wear rate will increase, affecting the service life. Therefore, when choosing a friction material, the appropriate friction material should be selected according to different needs.
Effects of other conditions
The different conditions of use also directly affect the characteristics of the friction material, such as surface pressure, speed and oil temperature, etc., which will not be repeated here. The specific impact will still depend on the test results.
Therefore, the coefficient of a specific friction material is not a specific value, but according to different test conditions, the friction coefficient of oil and a friction material is a range obtained after repeated trials.
3. Application of paper-based friction materials
At present, Carlisle (Carlisle braking and friction materials) paper-based friction materials are used in the brakes, transmissions and other transmission equipment of various vehicles and construction machinery such as construction machinery, agricultural machinery and industrial machinery due to their excellent friction performance. Widely used, it is an important class of friction materials.
The principles of paper-based friction materials in different vehicles (construction machinery, agricultural machinery, etc.) and different applications of vehicles (service brakes, parking brakes, gearboxes, etc.) are different, so Carlisle (Carlisle brakes and friction Materials) A variety of paper materials suitable for different applications have been developed for customers to use for different applications.
4. Conclusion
In order to meet the wider and more demanding conditions, Carlisle (Carlisle Brake and Friction Materials) is also working hard to develop paper-based friction materials with better performance, including wet friction materials with better performance than paper-based friction materials. At present, good progress has been made to provide customers with more choices for better applications.
