JOHN W. EVERT | Mechanical Engineering Technology
Introduction
Current brake rotor metallurgy has only two paths; grey iron, carbon ceramic, and derivations of each respective material; designs consist of a one or two-piece rotor that once the friction surface has reached a minimum thickness threshold it is discarded and replaced with an all new casting. A similar relationship exists between the brake rotor and a pneumatic tire; once the tread has worn down, the tire is replaced with a new unit, leaving the “worn” unit with approximately 90% of the overall structure intact. This project was motivated by a need for an alternative system that consists of a rotor structure with replaceable friction surfaces that is inexpensive to manufacture and maintain while both lighter in rotating mass as well as static mass.
Because of grey iron’s high material density, ρ = 7196 kg/m3, a typical brake rotor mass can be as much as 10-20 kg with most of that mass concentrated along the outside diameter furthest from the point of rotation. Potential energy, e.g. combustible fuel, is wasted overcoming the moment of inertia during acceleration and consequently extra brake pedal effort overcoming the flywheel effect during deceleration. Rust is also prone in areas that are not the friction surface. The internal venting channels proximal to the rotor faces degrade the effectiveness of heat dissipation through inhibiting centrifugal convection currents thereby the internal rotor temperature rises reducing pad friction efficacy.
A proposed structure of 6061-T6 aluminum, ρ = 2712 kg/m3, or similar material, for the rotor body with replaceable faces of a high friction ferrous material shall serve as the composite rotor structure. It is by this means that a lighter mass unit with similar of greater braking characteristics can be quantified.
