The reason why there is a scream when you step on the brake
Many people now have cars, but because of the epidemic, they will be isolated from driving at home for a period of time. If they are driving after the closure is lifted, when they step on the brake, the car will make a "rattling" sound. What is the reason?
It is normal that there is a little rust on the brake disc. On rainy days or in places with high humidity, the rust on the brake disc can be clearly seen after stopping overnight. The brake disc is a mixture of various materials, including metal powder. When a small hard point rubs against the metal disc, it will definitely make a noise. Most of the brake pads are compressed and formed by recycling and reprocessing of waste metal. In fact, the brake pads are not a whole, and there are many metal impurities inside. The abnormal noise is caused by the sharp friction between a metal hard point and the brake disc at a certain wear point. The solution is to step on the brake again to solve the abnormal noise. The purpose is to wear the brake pad thickness again and remove the hard point.
The brake pad is mainly composed of brake pad backing plate and friction material. The main cause of abnormal noise is caused by some small iron scraps in the friction material. Iron filings are uniformly distributed in the friction material. When iron scraps rub against the brake disc, they will make abnormal noise. The influencing factors include but are not limited to friction coefficient, brake pressure, speed, material mechanical characteristics, wear, corrosion, temperature, humidity, natural frequency of brake disc, brake pad, caliper, etc. It is reasonable to say that most automobile enterprises have solved the screaming under most working conditions by various means before leaving the factory.
However, there are too many elements of the brake system, and it is very difficult to completely eliminate the squeal with such complicated mechanism