The Application of Nitrile Butadiene Rubber (NBR) in Brake Shoes Production
Nitrile Butadiene Rubber (NBR) has found wide – spread application in the production of brake shoes, playing a vital role in the composition of brake shoes mixtures and mixes, especially in brake shoes friction materials. This material brings both distinct advantages and some limitations to the brake shoe manufacturing process and the final product performance.
Advantages
- Excellent Oil Resistance
- NBR exhibits remarkable oil resistance, which is crucial for brake shoes. In a test environment where brake shoes are exposed to common brake fluids, brake shoes made with NBR – containing friction materials showed only a 2 – 5% volume swell after 1000 hours of immersion, while those without NBR swelled by 15 – 20%. This high – level of oil resistance ensures that the brake shoes maintain their structural integrity and performance even in the presence of oil – based contaminants, preventing premature wear and degradation of the friction materials.
- Good Abrasion Resistance
- The abrasion resistance of NBR contributes significantly to the durability of brake shoes. Laboratory tests indicate that brake shoes with NBR – reinforced friction materials can endure up to 500,000 braking cycles with a wear rate of less than 0.1 mm per 10,000 cycles. In contrast, brake shoes without NBR in their friction materials may only withstand 200,000 – 300,000 braking cycles before showing signs of excessive wear, with a wear rate of 0.2 – 0.3 mm per 10,000 cycles. This enhanced abrasion resistance leads to a longer service life for the brake shoes, reducing the frequency of replacements.
- High – Temperature Resistance
- NBR can tolerate relatively high temperatures. It can maintain its mechanical properties and friction performance up to 150 – 180°C. During high – speed braking, the temperature of brake shoes can rise rapidly. NBR – based brake shoes can effectively dissipate heat and prevent the friction coefficient from dropping significantly. For example, in a high – speed braking test at 120 km/h, the friction coefficient of NBR – containing brake shoes remained above 0.35, while non – NBR brake shoes saw their friction coefficient drop to 0.2 – 0.25.
Disadvantages
- Low – Temperature Brittleness
- One of the main drawbacks of NBR is its low – temperature brittleness. At temperatures below – 20°C, the elasticity of NBR – based brake shoes decreases significantly. In cold – climate regions, this can lead to a higher risk of cracking and reduced braking performance. For instance, in a low – temperature braking test at – 30°C, brake shoes with NBR – based friction materials showed a 30 – 40% reduction in impact strength compared to room – temperature conditions.
- Cost Factor
- NBR is relatively more expensive than some alternative materials used in brake shoe production. The cost of NBR can increase the production cost of brake shoes by about 10 – 15% compared to using traditional rubber materials. For large – scale brake shoe manufacturers, this cost increment can translate into a substantial additional expense, especially when producing a high volume of brake shoes.
In summary, Nitrile Butadiene Rubber offers significant advantages in terms of oil resistance, abrasion resistance, and high – temperature performance in brake shoe production. However, its low – temperature brittleness and cost implications need to be carefully considered when choosing materials for brake shoes.