Date of Award

1-1-2019

Publication Type

Master Thesis

Degree Name

M.A.Sc.

Department

Mechanical, Automotive, and Materials Engineering

Keywords

Brakes, Noise, Rotors

Supervisor

Andrzej Sobiesiak

Rights

info:eu-repo/semantics/embargoedAccess

Abstract

Brake Squeal Noise is a significant concern in the automotive industry and incurs enormous costs during brake system development and in brake system warranty. Several methods are utilized to minimize brake squeal, including frequency manipulation of individual brake system components through design and material modifications, active damping elements like pad shims and insulators, which typically add mass and cost to the brake system, as well as retesting costs. Brake rotors are made of grey cast iron due to their low cost, good machinability, wear and damping properties. Strength requirements limit the material damping obtainable on a consistent basis. Other methods to improve rotor damping include the use of steel inserts in the rotor plates and EDM machining of the brake rotors. Parts made with either process have been observed to reach very high levels of damping (Q factor of ~ 200) and entirely eliminate noise occurrences in the brake system.This research involves the characterization of the material and the additional processes required to achieve highly damped rotors, with a Q factor in the range of 100 to 300, which can provide significant brake noise reduction. It was discovered that electrical or magnetic processing of the rotors can create damping improvements in the range of 10 to 50 %, which are beneficial to reducing noise occurrences. EDM processing was primarily used for the study and Q factor improvements in the range of 30 to 50 % observed. Rotors with High C.E., Large Type A graphite with flake size 2 to 4, showed the largest benefits from the processing. Process DOE showed no effects of current on the damping improvements. A low processing time of 5 seconds on Non FNC rotors generated over 30 % damping improvements consistently. Noise occurrence reductions of 80 to 100 % were seen with the processed rotors. No detrimental effects were noted on other rotor performance characteristics including thermal cracking, brake torque variation, wear, and corrosion. Effects of time, temperature and wear on the damping improvements have been researched, and no significant losses were seen in typical operating conditions.

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