Materials Used in Braking System

A vehicle's braking system is a complex structure consisting of multiple parts. These components’ materials are crucial during manufacturing processes because each of them serves a different function.

A braking system contains various working principles, such as:

• Hydraulic Principle

• Friction Principle

• Heat Dissipation Principle

These principles explain the transmission of brake fluid, the heat generated by the friction force, and its dissipation.

Now let’s examine the materials used.

Brake Pads & Shoes

The main purpose of these parts is to create a friction force by pressing either discs or drums.

Brake pads and shoes are utilized in different types of braking systems. While brake pads are mounted on brake discs and pressed against rotors, brake shoes are components of drum brake systems that press outward against brake drums. The brake shoe is the metal curved frame holding the friction material (lining). It is important to notice that both brake pads and linings are friction materials. However, the brake lining is used in brake drums, held and pressed by the brake shoe.

The materials must resist brake fade caused by an increase in temperature. The materials must recover quickly from high temperatures and resist wear caused by friction. Additionally, the friction coefficient must be carefully balanced. It is low enough to prevent the wheels from locking, on the other hand, high enough to ensure effective stopping power.

Materials for Brake Pads and Linings

Non-Asbestos Organic (NAO) Pads:

These pads are made from glass, rubber, carbon, and resins. They are quiet and soft, but they wear out faster. They are most commonly used in everyday passenger vehicles. Kevlar, rubber, and carbon are some of examples.

Semi-Metallic Pads:

They include metals like copper or steel mixed with graphite and resin for better heat resistance and performance. They are durable and provide better heat transfer, often used in performance and heavier vehicles.

Ceramic Pads:

They are mostly made from ceramic fibers. Offering high performance, less dust, with silence makes them more expensive, often used in luxury or high-performance vehicles.

Brake Discs & Drums

The material selection of both brake discs and drums is the most important one, because approximately 70% of the brake wear starts from these parts.

The material must provide high strength, high wear resistance, high thermal conductivity, and low thermal expansion.

The most used materials are:

• Cast iron

• Steel.

• Carbon-based materials

• Ceramic-based materials

Brake Fluid

By using hydraulic force, brake fluids transfer the pressure from the brake pedal to the brakes. It reduces wear and prevents internal corrosion. Brake fluids must withstand high temperatures. Because of high temperatures, the moisture might condense later and cause harm to the braking system. Brake fluids absorb moisture and prevent braking failures.

• DOT 3

• DOT 4

• DOT 5

• DOT 5.1

DOT 3, 4, and 5 are glycol-based fluids that absorb water, while DOT 5.1 is silicon-based and does not absorb water.

The braking system of a vehicle is a crucial component of safety. Choosing its materials is vital to ensure adequate performance, durability, and reliability. Each material, including brake pads, brake shoes, brake linings, brake discs, brake drums, and brake fluids, must be carefully selected to withstand high pressure, friction forces, and temperatures.

Eren Erden