Mass Production Demonstration of Aluminum Brake System 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 rotorapplications 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 rotor weight at a cost increase of less than $5/lb-saved without compromising brake performance. The objective of the combined Phase I/Phase II project is to demonstrate technical and mass production feasibilities of the proposed technology for OEM applications. In the Phase I project, several SCA rotors for 2011 Ford Focus front brake were manufactured and tested by Link Engineering Laboratories according to the test procedures: 1) Federal motor vehicle safety standard 135 test; 2) City, rural, and highway wear test; and 3) Squeal noise propensity. Road test of a car mounted with the rotors followed. The research provided 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. In the Phase II project, mass production of a SCA rotor will be demonstrated in collaboration with manufacturing partners. In addition, the SCA rotor will be selected by an automaker aiming at commercial application and go through the quality verification process. 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, 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.