How to judge the quality of the friction plate?
The friction between the disc brake pad and the brake disc forms a friction pair, which generates a braking torque and converts the kinetic energy of the car into heat energy. When braking, the weight of the vehicle is transferred to the front axle, and the brakes on the front wheels are inevitably subjected to a large braking force. Therefore, the front brake pads and brake discs are the most stressed elements in the vehicle, and they are subject to extreme high temperature, mechanical and chemical stress. Hualong friction editor tells you that the performance of a brake pad must meet three requirements: safety, comfort and service life. The criteria for evaluating brake pads mainly include the following factors:
1. Braking noise - in order to prevent noise, vibration damping devices are usually used on the brake friction pads, including vibration damping pads and anti-vibration glue
Braking noise is a characteristic of particular concern to users. Generally speaking, the noise is caused by the vibration caused by the unbalanced friction between the brake pad and the brake disc. The sound wave of this vibration can be discerned in the car. There are also many kinds of noise during braking. We generally distinguish them according to the stage of noise generation, such as the noise generated at the moment of braking, the noise accompanying the entire braking process, and the noise generated when the brake is released. The low-frequency noise of 0-50Hz is imperceptible in the car, and the driver of the noise of 500-1500Hz will not consider it as braking noise, but the driver of high-frequency noise of 1500-15000Hz will consider it as braking noise.
The main determinants of brake noise include brake pressure, pad temperature, vehicle speed and climatic conditions. In order to prevent noise, vibration damping devices are usually used on the brake friction pads, including damping pads and anti-vibration rubber.
2. Friction coefficient - a good brake pad, its friction coefficient must be high enough and stable under various driving conditions
The dynamic friction coefficient of the brake pads determines the braking force, and also plays a decisive role in the braking balance and the stability of vehicle handling during braking. A reduction in the coefficient of friction causes a considerable change in braking performance, perhaps resulting in a substantial increase in braking distance. Therefore, the coefficient of friction of the brake pads must be guaranteed to remain stable under all driving conditions (speed, temperature, humidity and pressure) and over the entire service life. That is to say, a good brake pad must have a high enough friction coefficient and be stable under various driving conditions.
3. Friction material - A good brake pad does not contain asbestos, not only that, but the friction material should also try to avoid expensive and uncertain properties of fibers and sulfides.
Appropriate friction lining formulation materials will ensure proper compressive strength. Friction lining materials are basically composed of four raw materials: metal materials, filler materials, slip agents and organic materials. The relative proportions of these materials depend on the specific use of the friction lining and the required coefficient of friction. Friction material formula is strictly confidential, only the manufacturer knows. In friction lining formulations, asbestos had been shown to be an effective wear-resistant material, but after it was known that asbestos fibers were harmful to health, this material was gradually replaced by other fibers. Today, good brake pads are absolutely asbestos-free, and not only that, but the friction material should also try to avoid expensive and uncertain properties of fibers and sulfides.
4. Shear strength - ensures that it will not fall off or crack even under extreme conditions
The shear strength of brake pads is another important measure. Whether it’s the shear strength of the pads themselves, or the bond between the brake pads and the backing plate, it’s important to ensure that they won’t come off or crack, even under extreme conditions.
