The Application of Nitrile Butadiene Rubber (NBR) in Brake Pads Production
In the manufacturing of brake pads, Nitrile Butadiene Rubber (NBR) has emerged as a crucial component, significantly influencing the performance and quality of the final product. As the automotive industry demands higher – performing and more reliable braking systems, understanding the role of NBR in brake pads production becomes essential.
1. Nitrile Butadiene Rubber in Brake Pads
Nitrile Butadiene Rubber is a synthetic rubber copolymer made from acrylonitrile and butadiene. Its chemical structure endows it with unique properties. The acrylonitrile content in NBR typically ranges from 18% – 50%, which has a direct impact on its performance. For example, NBR with a higher acrylonitrile content (around 40% – 50%) offers excellent oil resistance. It can withstand immersion in various automotive oils, such as brake fluid, without significant swelling or degradation. In fact, in standard oil – resistance tests, NBR with 40% acrylonitrile content showed less than 5% volume swelling after 72 hours of immersion in brake fluid at room temperature.
Moreover, NBR has good mechanical properties. Its tensile strength can reach up to 20 – 30 MPa, and the elongation at break is usually in the range of 300% – 600%. These mechanical properties make it suitable for withstanding the mechanical stresses generated during the braking process.
2. Incorporation into brake pads mixture
NBR is an important ingredient in the brake pads mixture. It is combined with other components such as friction – enhancing materials (like abrasives), binders, and fillers. In a typical brake pads mix, NBR usually accounts for 10% – 30% by weight. This proportion is carefully adjusted based on the desired performance of the brake pads. For instance, when aiming for better flexibility and shock – absorption in the brake pads, a higher proportion of NBR may be used.
The addition of NBR to the mixture improves the overall cohesion of the brake pads. It acts as a sort of “glue” that helps bind the different particles in the mixture together, ensuring that the brake pads maintain their structural integrity during use.
3. Role in brake pads friction materials
In brake pads friction materials, NBR plays a multi – faceted role. Firstly, it contributes to the friction – modulation properties of the brake pads. By adjusting the amount of NBR in the friction material, manufacturers can fine – tune the friction coefficient. In some cases, increasing the NBR content can slightly decrease the friction coefficient, which may be beneficial for applications where a more gentle braking force is required, such as in some luxury vehicles. However, this adjustment needs to be carefully balanced to ensure that the minimum braking performance requirements are still met.
Secondly, NBR’s elastic properties help in reducing the noise and vibration generated during braking. Brake pads with an appropriate amount of NBR have been found to reduce braking noise by up to 30% compared to those without NBR in the friction material.
Advantages of Using NBR in Brake Pads Production
- Excellent Oil Resistance: As mentioned earlier, NBR’s high oil resistance is a major advantage. Since brake pads are often exposed to brake fluid and other oils in the braking system, NBR’s ability to resist swelling and degradation in these environments ensures the long – term reliability of the brake pads. In a vehicle’s lifespan, brake pads with NBR can maintain their performance in the presence of oil contaminants for up to 5 – 7 years, while those without proper oil – resistant components may start to degrade after 2 – 3 years.
- Good Mechanical Properties: The high tensile strength and elongation at break of NBR enable the brake pads to endure the mechanical forces during braking. This results in a longer – lasting product. Brake pads with NBR have been shown to have a wear – life that is 20% – 30% longer than those without it, reducing the frequency of brake pad replacements.
- Noise and Vibration Reduction: NBR’s elastic nature helps in dampening the vibrations and reducing the noise generated during braking. This not only improves the driving comfort but also indicates better – performing brake pads. Vehicles equipped with brake pads containing NBR have a more pleasant braking experience, with reduced harshness and noise levels.
Disadvantages of Using NBR in Brake Pads Production
- High – Temperature Sensitivity: NBR has relatively poor heat resistance. At temperatures above 150 – 200°C, its mechanical and physical properties start to degrade. In high – speed or heavy – duty braking situations, where the temperature of the brake pads can exceed 200°C, NBR – based brake pads may experience a significant reduction in performance. For example, the friction coefficient may drop by 15% – 20% at temperatures around 250°C, leading to longer braking distances.
- Cost: NBR, especially high – quality grades with specific properties, can be relatively expensive. The cost of NBR can increase the overall production cost of brake pads by 10% – 20%. This cost factor may be a deterrent for some manufacturers, especially those aiming for cost – effective production.
- Limited Chemical Resistance to Some Chemicals: Although NBR is highly resistant to oils, it may not perform well in the presence of certain chemicals, such as strong oxidizing agents. In some industrial or special – use vehicles where the brake pads may be exposed to a wider range of chemicals, the limited chemical resistance of NBR can be a drawback.