Brass chips

Brass chips are a multifunctional additive. Their main roles are:

• Thermal Management: They act as an excellent thermal conductor, helping to dissipate the heat generated at the friction interface (pad-disc) to the rest of the pad body and brake caliper.
• Structural Reinforcement: They function as a metallic reinforcement that increases the mechanical integrity, toughness, and crack resistance of the friction composite.
• Friction Stabilization: They contribute to the formation of secondary plateaus on the pad's surface, helping to stabilize the coefficient of friction, especially at moderate to high temperatures.

Heat management is critical. Efficient heat dissipation, thanks to the conductivity of brass (~110-120 W/m·K), prevents overheating of the phenolic resin binder. This significantly reduces the risk of brake "fading" (loss of brake effectiveness at high temperatures) and minimizes thermal degradation of the material, leading to lower wear at elevated temperatures.

Brass, being softer than the brake disc's steel, does not generally act as an abrasive. Its main contribution is to stabilize the coefficient of friction by improving the thermal homogeneity of the surface. By reinforcing the matrix, it also increases the material's cohesive wear resistance, helping to maintain structural integrity under high mechanical and thermal loads.

The choice of particle size is a key parameter:

• Coarse Chips: Offer greater mechanical reinforcement and create very effective thermal "bridges."
• Fine Chips: Allow for a more homogeneous dispersion, resulting in uniform thermal conductivity and better compressibility.
  RIMSA's ability to offer custom granulometries is a crucial advantage, allowing the formulator to optimize processability and balance mechanical reinforcement with thermal conductivity.

The use of brass must align with two main regulations:

• Copper Restrictions: Environmental legislation (e.g., SAE J2975) restricts copper content. The copper in brass counts towards the total percentage, so the dosage must be adjusted to meet the limits (Level B: < 5% Cu; Level N: < 0.5% Cu).
• Lead Restrictions: Traditionally, recycled brass chips can contain lead (Pb), which was added to improve machinability. Lead is a highly restricted substance in the automotive industry and other markets (e.g., RoHS, REACH directives). It is imperative to ensure the material complies with the Pb limits required by the target market.

The recycled origin presents a challenge: potential variability in chemical composition and the presence of impurities. This is where supplier experience is fundamental. A supplier like RIMSA ensures consistency and quality through:

• Reliable Sources: Rigorous selection and approval of raw material suppliers.
• Strict Quality Control: Chemical analysis of every batch to ensure the composition (Cu/Zn alloy, levels of Pb and other impurities) remains within specifications.
• Manufacturing Expertise: A controlled manufacturing process that ensures consistent morphology and granulometry.
  This expertise guarantees that the formulator receives a reliable product from lot to lot, eliminating a critical source of variability in their production.