Optimisation of alumina coated lightweight brake rotor

Aluminium alloys have been used extensively in the automotive industry to reduce the weight of a vehicle and improve fuel consumption which in turn leads to a reduction in engine emissions. The main aim of the current study is to replace the conventional cast iron rotor material with a lightweight alternative such as coated aluminium alloy. The main challenge has been to meet both the cost and functional demands of modern mass-produced automotive braking systems. A sensitivity analysis based on the Taguchi approach was carried out to investigate the effect of various parameters on the thermal performance of a typical candidate disc brake. Wrought aluminium disc brake rotors coated with alumina on the rubbing surfaces were determined to have the best potential for replacing the conventional cast iron rotor at reasonable cost. Optimisation of the structure was subsequently carried out using a genetic algorithm on the selected coated aluminium disc brake rotor. This determines the optimum thickness of the coating and the composition of the substrate based on selected criteria. Prototype aluminium disc brake rotors were coated with alumina using the Plasma Electrolytic Oxidation (PEO) technique and the thermal performance of these lightweight rotors was investigated experimentally using a brake dynamometer. A high speed thermal imaging system was used to evaluate and measure the rubbing surface temperature of the coated brake rotors. The experimental results showed generally good agreement with the numerical predictions. The coated wrought aluminium disc brake rotor was demonstrated to give good thermal and friction performance up to relatively high rubbing surface temperatures of the order of 500°C.