Discussion on semi-metal formula of friction material
1. Definition of friction material formula:
Contains steel fiber, porous iron powder, friction-increasing filler, graphite, coke lubricant, etc. The content of steel fiber and iron powder is more than 40%.
2. Main features:
1. Lower cost.
2. High thermal conductivity.
3. Excellent wear resistance.
4. Suitable for heavy load braking conditions.
3. The main problems of friction materials:
1. Noise, vibration, and roughness are likely to cause low-frequency noise, accompanied by severe vibration of the car body.
2. There is a lot of dust (high temperature decay is not good).
3. The high metal content makes the braking force insufficient at low temperature and low speed, and it is easy to cause pedal fatigue.
4. The high thermal conductivity and heating rate make the heat be transferred to the brake caliper and its components, and this heat will accelerate the aging of components such as the brake caliper, piston sealing ring and return spring. High thermal conductivity will easily cause the friction material to thermally decompose and decay at high temperature too quickly, which will cause peeling or cracking of the brake lining.
5. Adhesiveness and easy to rust. After rusting, it will adhere to the pair or damage the pair, and the wear will increase.
Summary: Volume percentage is the most correct unit to measure friction materials. An excellent formulation engineer should take the initiative to understand the basic properties of various raw materials (density, particle size, hardness, moisture, chemical composition, elastic modulus), and at the same time should clearly know the impact of various friction materials on the micro and macro performance of friction material products. Influence. At present, as far as I know, in China, most formula design tests are based on weight ratio, in order to avoid the shortcomings of insufficient basic data on raw material performance. For the formulation of friction materials, it is very difficult to theoretically express the relationship between the amount of formulation components and the friction performance with simple and clear formulas, such as mixing time, pressing time, pressing pressure, holding time, release time, etc. Changes in factors such as air time, grinding method, and the material of the dual material will affect the braking performance during the braking process anytime and anywhere. As far as the formula itself is concerned, it is still impossible to accurately use theoretical methods to determine the ratio of various raw materials, and it is also impossible to deduce the direct quantitative relationship between the formula and the performance. Most of them rely on long-term accumulated experience. This requires our technicians to have a wealth of basic knowledge of the performance of friction materials and the spirit of assiduous research and more experiments.
