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Review of Brake Friction Materials for Future Development

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Review of Brake Friction Materials for Future Development View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by MAT Journals Journal of Mechanical and Mechanics Engineering Volume 3 Issue 2 Review of brake friction materials for future development K. Naresh Kumar a *, Dr. K. N. S. Suman b a * Assistant Professor, Mechanical dept, Anits Engineering college, Visakhapatnam b Assistant professor, Mechanical dept, Andhra University, Visakhapatnam Abstract Braking system in an automobile is always considered to be important for the designers. The main function of a braking system is to overcome vehicle’s momentum and stop the vehicle by means of friction. Now days, with the increase of innovative technology and by varying design procedures, newly designed automobiles with high speed sprung on to the market, which are throwing prime challenges for the braking system designers to control the speed of the vehicle. After the gradual phasing out of asbestos as a braking material in many parts of the world, due to its widespread complaints as a carcinogenic material, automobile brake friction industry and people are looking for suitable alternatives to replace asbestos material. There is need to develop new friction materials to meet the stringent requirements of customers, such as effective braking performance and less squealing action .Therefore, the main challenge for the designer is to develop a brake friction material which intended to serve its effective braking performance and being eco friendly in nature. Therefore, with in this paper, an overall review of the research carried out in the area of friction materials is presented and the affect of fiber, filler and other ingredients on the braking performance is studied. Various experimental techniques used to study the behavior of squealing action in automobile braking is presented. Key words: Brake friction materials, friction and wear, squealing, fade, recovery a* Author correspondence Email: [email protected] , Tel: 91-9949717058 1. INTRODUCTION material temperature, friction material Brake pads convert the kinetic energy of contact area, friction material finish, heat the vehicle to thermal energy by means of removal rate, ability to operate over friction. Two brake pads are contained in various atmospheric conditions and fade the brake caliper with their friction resistance. In addition to all these factors, surfaces facing the rotor. When, the brakes the other factors that affect the friction are hydraulically applied, the caliper development are weight transfer, tire and clamps or squeezes the two pads together road conditions, dimensions of brake in to the spinning rotor to slow/stop the drum, engine size and drive train gearing, vehicle. During this process, the pads are and water on brake linings etc. subjected to wear. The wear rate mainly Fig 1 & 2 shows a typical disk brake and depends up on the type of friction material assembly found in passenger vehicles. used, pressure applied on the pads, friction 1 Page 1-29 © MAT Journals 2017. All Rights Reserved Journal of Mechanical and Mechanics Engineering Volume 3 Issue 2 Fig1. Automobile disc brake with friction material Fig 2. Assembly of automobile disc with friction material The main characteristics of friction 1.1 Classification of friction materials materials should possess are [1] In the past, asbestos reinforced fiber (a) Maintain a sufficiently high coefficient friction material is widely used because of of friction with the brake disc. its excellent comprehensive performance (b) Not to decompose or break down in such as low density, high mechanical such a way that the friction coefficient properties, high melting point, high with the brake disc is compromised, at friction coefficient, and less wear rate on high temperatures. disc. It has been proved recently, that (c) Exhibit stable and consistent asbestos is carcinogenic to human coefficient of friction with the brake respiratory organs and cannot be used as a disc. friction material [2, 3]. Based on the type (d) Wear resistant. of matrix material, brake friction materials (e) Able to dissipate heat to the can be divided in to metallic, Semi surroundings. metallic, and non metallic. (f) Having sufficient fade resistance. 1.1.1 Metallic matrix friction material (g) Induce less squealing action and Depending up on the type of production should be operated over different technique, the metallic matrix friction atmospheric conditions. materials can be divided in to two types i.e. metal casted and powder metallurgical. Steel, cast iron, bronze etc. can be 2 Page 1-29 © MAT Journals 2017. All Rights Reserved Journal of Mechanical and Mechanics Engineering Volume 3 Issue 2 categorized as main constituents for metal exhibits high strength and toughness and casted friction materials. Powder superior thermal stability. At present, C-C metallurgy friction materials mainly Composite friction material was mainly include iron based, copper based and used in aero planes and race cars. combination of iron and copper based. Among the above mentioned classified Among them, iron based friction materials friction materials, Powder metallurgy and has high temperature strength, hardness, organic friction materials are widely been and thermal stability. While, the copper used in various applications. Organic based friction materials has more stable friction material was most widely used due friction coefficient, greater thermal to its simple preparation method, excellent conductivity and wear resistance. Iron and tribological properties and eco copper combination made friction friendliness. Organic friction material materials having same content of copper consists of following components [1] and iron possess excellent mechanical (a) Binder: The binder sticks all properties and good wear resistance. components together. The binder Powder metallurgy friction materials are selected, should possess excellent heat widely used in trucks and trains having a resistance. heavy braking load and extremely high (b) Reinforcing fibers: The Reinforced speed. fibers are used to improve friction performance and strength. 1.1.2 Semi metallic matrix friction (c) Frictional additives: Frictional material additives are responsible to improve Semi metallic friction material consists of friction properties of the brake pads combination of fibers and metallic and they are comprised of a mixture of powders. Prominent fibers predominantly abrasives and lubricants. The lubricant in use are ceramic, metallic, carbon and is generally used to reduce the wear of aramid. Whereas metallic powders are friction material and coefficient of mainly of copper and iron. These friction and abrasive is used to materials possess excellent tribological improve the coefficient of friction. properties and high heat resistance. The (d) Fillers: Fillers are used to improve the main disadvantages of semi metallic manufacturability of brake pad and matrix friction material are low frequency reduce the cost. noise, easy rusting, and serious damage to 2. Friction and wear behaviors of brake disc. Presently, semi metallic matrix various materials friction material is widely used in Friction and wear behaviors of friction automobiles, motor cycles and other light material depend mainly on the following weight vehicles. important factors [4] a) Selection of friction material for 1.1.3 Nonmetallic matrix friction material fabrication. Non metallic matrix friction material b) Manufacturing method involved for consists of organic fibers such as Kevlar, fabrication. Carbon etc. as reinforced fibers in c) Material characteristics such as combination with other ingredients such as Physical, chemical and mechanical modified resin by rubber powder, properties of friction materials. frictional additives, and filler materials. d) Braking influential parameters such as These materials are solidified by pressing braking pressure, initial braking against hot press. There are a number of speed, braking time, temperature rise nonmetallic matrix friction materials, out in braking etc. of which carbon –carbon friction material 3 Page 1-29 © MAT Journals 2017. All Rights Reserved Journal of Mechanical and Mechanics Engineering Volume 3 Issue 2 e) Other Conditions such as Surrounding natural fiber composites and their temperature, humidity, air flow etc. mechanical Performance. It was observed f) Structural parameters such as Shape, that the mechanical properties of the fiber size, contact of brake pair etc. are improved due to inclusion of various Friction material characteristics play a filler materials. There is need to improve vital role to improve the performance of moisture resistance of the fiber in future. materials. Among, the different types of Emad omrani, Pradeep L Menezes [6] materials available for manufacturing, investigated about tribological behavior of organic type of composite materials are polymer matrix composites reinforced widely used in the industry. Now a days, with natural fibers and observed that composite materials plays a promising chemically treated natural fiber gives good role in several fields of applications like tribological behavior and better friction aerospace, automobiles, sports items, compared to untreated conventional fibers. bridge construction and pressure vessels The type of chemical treatment and fiber etc.. The advantages of composite orientation are two important parameters materials are ease of process ability, less to concentrate in order to achieve good weight, corrosion resistance, low cost and strength. Umar Nirmal
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