Feasibility Study on an Aluminum Brake Systems for OEM Applications

Public awareness of energy saving and environmental concerns raises the demand for better fuel efficiency and weight reduction of vehicles. Weight reduction must also be cost effective for consumers, meet or exceed current and planned safety requirements, meet consumer expectations for vehicle performance and durability. The current brake systems consisting of rotors and calipers made of cast iron are heavy and normally experience severe corrosion. Aluminum is an excellent candidate material for brake applications. The major technical barriers preventing the use of aluminum in brake rotor applications include poor wear resistance and inability to withstand elevated surface temperatures generated during braking. The proposed solution is to develop an innovative aluminum brake system consisting of four steel clad aluminum (SCA) rotors, four aluminum calipers and four aluminum wheels for passenger cars, which utilizes the connected aluminum wheel as the major heat sink/radiator to dissipate braking heat more efficiently, resulting in significantly lower brake working temperatures. The proposed technology also includes a reliable steel and aluminum bonding technique which incorporates steel with a higher pad/rotor friction coefficient and dozens of slots to increase braking friction and eliminate the problem of steel and aluminum thermal mismatch. The proposed technology will save over 30% cast iron brake weight at less than $5/lb-saved without compromising brake performance. The objective of the Phase I project is to demonstrate technical feasibility of the proposed technology for OEM applications. In the Phase I project, a couple of SCA rotor prototypes for a selected model of cars will be manufactured and tested on a dynamometer machine at the conditions simulating real driving by Link Engineering Laboratories according to the test procedures: 1) Federal motor vehicle safety standard 135 test (SAE J2784); 2) City, rural, and highway wear test (SAE J2707 method B); and 3) Squeal noise propensity (SAE J2521). Road test of a car mounted with the rotor prototypes will follow. The proposed research will provide the needed results of overcoming the technical hurdle of very tight disc thickness variation (DTV) control and reaching the DTV goal of not greater than 0.0002” for new rotors and 0.0005” for rotors in service. The proposed aluminum brake system aims at replacing the widely used cast iron brake systems and will reduce 20-60 pounds of unsprung weight for a passenger car and promise 2-4% energy savings for vehicles. If successfully developed and commercialized through Phases I, II, III and beyond, considering the great number of vehicles on the road, the proposed technology could save huge amounts of gasoline every year, worth over 10 billion dollars and reduce enormous amounts of CO2, CO, hydrocarbons, and NOx emissions annually in the US. In addition, the SCA rotors are produced using metal mold casting, which are much more environmentally friendly than the sand mold casting process used by cast iron rotors.