Disc Brake Pads are widely used due to their wear resistance and thermal stability, but does it increase brake noise?

Disc brake pads are widely used in various vehicles due to their wear resistance and thermal stability, but in actual use, they may indeed cause brake noise problems. The following is a detailed analysis of this phenomenon and its causes and solutions:

Brake noise usually manifests as a sharp whistle, low-frequency hum or metal friction sound. Its main sources include the following aspects:
Resonance effect
When the brake pad contacts the brake disc, the high-frequency vibration between the two may cause resonance. This resonance amplifies the sound energy at a specific frequency, resulting in a harsh whistle.
Material properties
Brake pads made of different materials have different friction coefficients and thermal conductivity. For example:
Semi-metallic brake pads: Due to the large amount of metal particles contained, they are prone to generate greater friction when braking at high temperatures or high speeds, which may cause noise.
Ceramic brake pads: Although ceramic materials are generally quieter, they may also cause noise if the surface coating is worn or installed improperly.
Temperature changes
Brake pads may undergo thermal deformation or surface hardening under high temperature conditions, resulting in an uneven friction interface, which increases the possibility of noise.
Structural design issues
The design details of the brake pad (such as the back plate shape, groove structure and installation of the silencer) are crucial to noise control. If the design is unreasonable, vibration and noise may be aggravated.

Semi-metallic brake pads are favored for their high wear resistance and good thermal stability, but their material properties also make them more prone to noise problems:
High friction coefficient
Semi-metallic brake pads usually contain up to 30%-70% metal components (such as steel fibers, copper powder, etc.), which will produce high friction during braking and increase the possibility of vibration.
Difference in thermal expansion
The thermal expansion rate of metal components at high temperatures may be inconsistent with that of the brake disc, which will cause unstable contact surfaces and cause vibration and noise.
Surface hardening
After long-term use, the surface of semi-metallic brake pads may harden due to high temperatures, forming an irregular friction interface, which further aggravates noise.

How to reduce brake noise

Optimize material formulation
Develop new composite materials to reduce metal content while maintaining wear resistance and thermal stability.
Add vibration damping materials (such as graphite, adhesives) to absorb vibration energy.
Improve structural design
Install a shim on the back plate of the brake pad to reduce vibration transmission.
Design a reasonable groove structure (such as a wavy or bevel groove) to improve heat dissipation and reduce the unevenness of the friction interface.
Ensure proper installation
Ensure that the contact surface between the brake pad and the brake disc is clean and oil-free.
Use special grease to apply to the non-friction areas of the brake pad (such as the back plate and caliper guide) to reduce friction between moving parts.
Periodic maintenance
Check the wear of the brake pad and brake disc regularly, and replace excessively worn parts in time.
Avoid long-term continuous braking to prevent high temperatures from causing the surface of the brake pad to harden.
Choose the right product
Choose the right brake pad material according to the vehicle type and driving habits. For example, a quieter ceramic brake pad can be selected for urban driving, while a more wear-resistant semi-metallic brake pad can be selected for high-performance vehicles.
Although semi-metallic brake pads are widely used due to their wear resistance and thermal stability, they do increase the risk of brake noise due to their high friction coefficient and metal composition. By optimizing material formula, improving structural design and strengthening daily maintenance, noise problems can be effectively reduced while ensuring the safety and comfort of the braking system.

For car owners, understanding the working principle and common problems of brake pads can help better select and maintain the brake system, thereby improving driving experience and driving safety.