If the friction coefficient of brake friction pads is too high or too low, it will affect the braking performance of the car. Especially when the car needs emergency braking at high speed, if the friction coefficient is too low, the brake will be insensitive, and if the friction coefficient is too high, the tire will lock, which will cause the vehicle to drift and skid, posing a serious threat to driving safety. According to national standards, the suitable working temperature of brake friction pads is 100~350℃. However, when the temperature of many inferior brake friction pads reaches 250℃, their friction coefficient will drop sharply, and the brake will completely fail at this time. Generally speaking, according to SAE standards, brake friction pad manufacturers will use FF-level rating coefficients, that is, the friction rating coefficient is 0.35~0.45.
1. What is the relationship between the life of brake friction pads and hardness?
There is no certain relationship between the life of brake friction pads and surface hardness. However, if the surface hardness is high, the actual contact area between the brake friction pad and the brake disc is small, which often affects the service life. The main factors affecting the life of brake friction pads include hardness, strength, and wear of friction materials. Generally speaking, the service life of the front brake friction pad is 30,000 km, and the service life of the rear brake friction pad is 120,000 km.
2. Why does the vibration occur during braking?
It is often caused by the deformation of the brake friction pad or brake disc, which is related to the material, processing accuracy and thermal deformation of the brake friction pad and brake disc. The main reasons are uneven thickness of the brake disc, poor roundness of the brake drum, uneven wear of the brake friction pad, thermal deformation and hot spots.
In addition, deformation or improper installation of the brake caliper and unstable friction coefficient of the brake friction pad can also cause vibration during braking. In addition, if the vibration frequency generated by the brake friction pad during braking resonates with the suspension system, it will also cause vibration.
2. Impact on braking performance after wading?
Because there is a layer of water film between the brake friction pad/shoe and the brake disc/drum after wading, the friction is reduced, which will affect the braking effect, and the water in the brake drum is not easy to disperse.
For disc brakes, this kind of wading will have a lower impact on the braking effect, because the contact area of the brake pad of the disc brake is small and it is exposed to the outside, so no water droplets will remain. When the wheel rotates, due to the centrifugal force, the water droplets on the brake disc will quickly dissipate. As long as you step on the brake a few times after wading, the remaining water layer will be removed.
But for drum brakes, you must step on the brake while walking after wading, that is, step on the accelerator and step on the brake at the same time. After several consecutive times, the water between the brake shoe and the brake drum can be evaporated, and then the braking effect can be restored.
3. Why is there noise when braking?
The noise during braking is mainly caused by the resonance or mutual interference of related parts of the suspension system. However, there are also noises or screams caused by improper use or deformation of the brake disc material, unqualified hardness, porosity, friction characteristics and compression characteristics of the brake friction pad, damp rust of the brake friction pad and brake disc (only a few brakes are needed to restore), the metal wire in the brake friction pad formula is too hard, the brake friction pad wear alarm, and mechanical brake friction pad scraping disc.
4. Why does the newly installed brake friction pad have a soft braking phenomenon?
After replacing the new brake friction pad, the brake may be soft. The possible reasons are: the brake friction pad is not installed in accordance with the standard, the brake disc surface is contaminated and not cleaned, the brake pipeline is faulty or the brake fluid is insufficient, the exhaust in the brake hydraulic cylinder is not thorough, the brake disc is excessively worn and the surface is uneven, and the brake friction pad quality is unqualified.
5. Why does the brake hysteresis phenomenon occur?
The possible reasons for the brake hysteresis phenomenon are: the brake return spring fails, the gap between the brake friction pad and the brake disc is improper or the assembly size is too tight, the brake friction pad thermal expansion performance is unqualified, and the parking brake return is poor.
6. Why does it smoke when braking?
The brake friction pad contains about 20% organic matter. When the temperature is too high, it will decompose and smoke, and form a layer of oily substance on the surface of the friction pad, affecting the braking effect. The possible reasons for this phenomenon are: frequent braking when going downhill, causing excessive temperature and smoke; the organic content in the formula of the brake friction pad is unqualified and exceeds the standard.
7. Why does the back plate of the brake friction pad fall off?
There are two situations in which the back plate of the brake friction pad falls off. One is that cracks occur between the back plate and the friction material; the other is that cracks occur in the friction material itself. The possible reasons are: poor pre-processing of the back plate, poor stability of the friction material, unqualified pressing process, poor quality of adhesive, high operating temperature, incorrect installation, impact and knocking.
8. What is the function of the inner groove of the brake friction pad?
The function of the inner groove of the brake friction pad is to discharge gas, reduce noise and change the natural frequency of the product, discharge wear debris, and enhance the adhesion between the friction material and the back plate.
DONGYING BORUI BRAKE SYSTEM CO.,LTD.
