Materials and Manufacture - The Production of Brake Discs - Coursework Example

Materials and Manufacture Name: Institution: Section A Brakes are devices used to stop or slow an automobile. They are crucial for the safe movement of vehicles. When a vehicle is in motion, it generates kinetic energy. Therefore, for a car to effectively slow down, this energy must decrease. This is achievable through the transformation of kinetic energy into another form of energy. Hence, drivers make the use of brakes to convert kinetic energy into heat energy. One of the most prominent types of brakes is the disc brake. They operate in the same manner as those of bicycle. An individual pushes the block against the spinning wheel, hence causing friction, which converts kinetic energy into heat energy. Vehicles use two of these braking blocks, one on each side of the wheel, thus keeping the wheel stable. Immediately after pushing the brake pedal, the two blocks press against the disc of the spinning wheel. Both the wheel and disc are jointly attached and spin together. When one decreases the speed of the disc, the wheel slows (Bryant, 2013). Brake disc is a very important component of the braking system, thus the material used to produce it must have reliable and stable wear and frictional properties under varying conditions of velocity, environment and temperature, durability, and load. There are different factors that persons consider when selecting a material for brake discs. The most crucial consideration is the ability of the material to withstand friction and should also have less abrasive wear. Also, the stuff must be able to withstand the high degree of temperatures that result from friction. Any design of the brake disc requires its material to have thermal storage capacity that prevent distortion or cracking from thermal stress (Maleque, 2010, p.978). Proper selection of material is crucial when a person is planning to manufacture a given product. This is achievable through the use of CES Materials Selection Software. CES has two major features; material selection using various attributes, and material property information from ceramics, polymers, composites, and metals. Furthermore, CES has process selector that assist in screening functions. Hence, these functions provide an opportunity for evaluation of materials’ impact on the product to be manufactured. CES selector provides a simple and quick route to identify materials for manufacturing of brake discs. The software also provides alternatives for improving a certain material selected for brake disc production. When using gray cast iron, metal matrix composites, carbon-carbon composite, and ceramic-carbon composite to produce brake disc, CES software assist the manufacturer to identify both mechanical and physical properties of the materials, hence gains knowledge on different modification that can be done on them in order to suit the requirements of a good brake disc (Ashby, 2005, p.558). The process involves some exercises organized into nine sections; introduction to exercises, devising concepts, utilization of material selection charts, translation, derivation and the use of material indices, selecting processes, multiple objectives and constraints, selecting shape and material, and hybrid materials. These exercises assist in selecting materials, shape and processes, and in selection of hybrid materials in case there is no material that meets the design requirements. The CES software assists in creation of charts, then in application line selection or appropriate box. The results from both levels 1 or 2 are often the same as those attained from hard copy charts made using level two database. Therefore, the software provides links to processes allowing a search by the use of level 3 database, and also gives access to essential information through the “Search Web” function. This way, an object such as gray cast iron is easy to choose from other materials because of its good properties (Ashby, 2005, p.559). Section B Cast iron is one of the most prominent materials that experts use to manufacture brake discs. Gray cast iron is one type of cast iron. It is traditionally preferred because of its excellent properties such as good castability, flexibility, good machinability, high internal damping capacity, wear resistance, good finishing surface, and high modulus of elasticity. Gray cost iron is affordable because of its low cost, 20-40 percent cheaper than steel. The presence of graphite flakes dispersed in ferrous matrix, characterizes the microstructure of grey cast iron. The key aspects that determine the mechanical behavior of Gray cast iron is the size, amount, distribution, and morphology of the graphite flakes. Foundry practices that influence the growth and nucleation of graphite flakes ensure that the cast iron produced meets the desired properties (Collini & Nicoletto, 2008, p. 529). Metal-matrix composites are also necessary in the making of brake discs. A composite material refers to an object that consists of two or more chemically and physically distinct phases. Hence, composites have more superior properties than those of the individual components. In addition, the manufacturers normally distribute the reinforcing element in the matrix or continuous constituent. Therefore, when a matrix is a metal, its composite is known as a metal-matrix composite. In metal-matrix composite, the reinforcements are in form of short fibers, particles, continuous fibers, and whiskers. Continuous fiber metal-matrix composite is one of the metal-matrix composite used in the production of brake discs. It is popular for its high strength, high thermal conductivity, can be heat-treated through a process called aging, and excellent toughness. The microstructure of the continuous fiber metal-matrix shows a multilayered composite with progressive thicker layers (Chawla, 2010, p.1). Carbon-carbon composites rank first among all ceramic composites materials that have excellent properties and applications in different sectors. Their properties and density depend on the volume fraction and type of reinforcement, heat treatment temperature, and matrix precursor used. Carbon-carbon composites can withstand high temperatures, and they have good frictional properties, high thermal conductivity and oxidation resistance at high temperatures. Processing of carbon-carbon composites influences their microstructure. Therefore, the matrix microstructure governs the properties of carbon-carbon composites. People mostly desire a randomly oriented carbon matrix due to its excellent electrical and thermal properties (Manocha, 2003, p.353). Ceramic-carbon composites retain the properties of both ceramic and carbon material. These properties include; good resistance to high temperatures, high mechanical strength, resistance to oxidation and corrosion, self lubrication, and well thermal and electrical conductivity. One type of ceramic-carbon composite is C-Sic-B4C. It meets all the requirements needed for the manufacture of the brakes discs. Its microstructure does not change even under severe environments and high temperatures; hence it is suitable as a material for the brake discs. C-Sic-B4C is prepared through hot-press sintering process to achieve good properties (Yang, 2000, p. 388). Section C Factories make brakes discs using cast iron through the casting process. The process involves introduction of molten metal into a mold, allowing cooling in the shape desired, and then ejecting to attain a fabricated product or casing. Thus, four key elements are critical in the casting process; pattern, cores, mold, and the part. The pattern is a template that is of equal dimensions as the product under manufacture and is important to create cavity in the casting material such as green sand. Cores are necessary to make holes or tunnels in the finished mold. Tunnels assist in the removal of gases when pouring in the molten metal. There are two types of casting; expandable and non-expandable. Non-expandable mold casting is the most common in manufacturing of brake discs since it does not require reformation after every production cycle, unlike in expendable casting processes. Die casting is one type of non-expandable casting. It is the best method of making brake disc. In the die-casting method, one injects the liquid metal into the mould at a high pressure of approximately 10-210Mpa. This results to a uniform part, with a good surface finish which is dimensionally accurate. This makes one to eliminate some post-machining operation or sometimes do a very light machining to bring dimensions to the actual size desired (Ibrahim, 2013, p.13). Industries manufacture the metal-matrix composite brake disks are manufactured casting process like semi permanent gravity casting. This is because casting helps manufacturers to add any alloy they like in order to achieve a composite with desirable properties. Additionally, lightweight metal-matrix composite brakes produced provide reduced braking distance and increased acceleration. Further, metal-matrix discs reduce wear and noise and tend to have more uniform friction when an individual applies the brakes. Moreover, these brake discs have better radiation survivability and transverse properties, and improved joining characteristics compared to other metals (Adebisi, 2011, p.474). In earlier days, people made brake discs from molten ceramic materials. However, researchers have found out that carbon-carbon composites would be a good alternative for brittle ceramic materials. Brake discs made of carbon-carbon composite are safe from oxidation that occurs due to repeated excursions at high temperatures during braking. Thus, oxidation protection is attainable through the application of a glass-forming penetrant that blocks active sites and by also adding an inhibitor by fabrication. The manufacture of carbon-carbon composites brakes discs start by fibre consolidation. Thereafter, one carries out the heat treatment followed by machining to bring out the desired dimensions. Persons carry out the oxidation protection on the different parts before doing the assembling process (savage, 2007 p.325). A carbon-ceramic brake disc is easy to produce in three different stages in order to meet the particular layout of a vehicle. They include; numerical modeling, construction and testing of different prototypes, and testing on the actual vehicle. An individual simulates the brake disk numerically using a computer to check the particular model data of the car. In addition, calculations for the carbon ceramic brake disks follow the process. The numerical model provides the design of the particular cooling vanes in order to optimize fluids dynamics. The numerical model results inform the making of the prototypes of the brakes. Testing occurs by matching the prototype with matched calipers and brake pads. In the final stage, the carbon-ceramic disks undergo testing on a vehicle. On the test runs, the driver examines carefully their performance and the computer gives analysis of the measured key results (SGL Group Carbon Company, 2013). Every material has its own property profile. One can classify the properties of materials in key groups; chemical and physical. On the other hand, materials bearing different properties undergo the manufacturing processes for conversion into final products. However, the suitability of a material to a certain process depends on its properties. A manufacturing process may change the microstructure or properties of a given material. Some of the most prominent brake discs manufacturing processes include; casting, forming, joining processes, powder methods, machining, heat treatment, finishing, and special methods. For instance, welding is one of the joining processes used widely by many manufacturers. When welding metallic alloys, phase transformations take place due to temperature changes. In addition, the cooling rate done after welding influences the resulting microstructure. Steels tend to form martensitic structure from austenite. However, if the carbon content is more, the forming of high amount of martensite occurs and the welding area becomes brittle. Also, high sulphur content makes the welding area to be more brittle. Other metals undergo different microstructure changes depending on the manufacturing process in use. For example, one way of improving the ability of heat transfer in cast iron is through increase in thermal diffusivity. Heat diffusivity is important for brake designs because it is necessary when calculating heat conductivity of the cast iron. Brakes discs that have improved thermal conductivity have high thermal fatigue strength. Therefore, the brake disc performance improves if the properties of gray cast iron improve (Aran, 2007, p. 152). Section D Flexible Manufacturing Systems (FMS) and Computer Integrated Manufacturing (CIM) are the two automation methods used often. A Flexible Manufacturing system makes it possible for unmanned production to take place at desirable capacities. In earlier days, FMS was very complex and large because it consisted of sophisticated material handling systems and many Computer Numerical Controlled machines (CNC). They were expensive and much automated, hence controlled by complex software. Thus, only a few companies were able to invest in FMS. Currently, there are smaller versions of FMS known as Flexible Manufacturing Cells (FMC). Therefore, people term the CNC machines as flexible cells and they are consider them as flexible manufacturing systems. Hence, a Flexible Manufacturing System composes of different machine tools with tool handling devices like robots that can easily handle a family of parts that it has been developed and designed for. There are advantages and disadvantages of implementing FMS. Some of the advantages include; it is faster, requires low direct labor cost, provides better and consistent quality, it has low cost per unit of output, and the system ensures that there are minimal chances of rejects and repairs, rework, and reduced errors. Some of the disadvantages of FMS include; expensive installation, complicated manufacturing systems, there are substantial pre-planning activities, and a limited liability to adapt to different changes in product mix or product (Dsianita, 2013). Computer Integrated Manufacturing (CIM) has provided a means of producing more sophisticated products, thereby improving productivity of the outputs of companies. In CIM system, hard drives help to store data, thus allowing easy retrieval or manipulation of the information. Further, the processing of information into products’ production is streamlined within software and hardware. This allows operators to modify programs to improve the quality of the items. CIM system also provides appropriate algorithms used to bring data together. There are several disadvantages of CIM system that evolve from its installation challenges. First, it is difficult to get all machines within a factory to work using the same system. This is because different machines carry out different tasks. In addition, it is hard to get employees with experience on how to feed the relevant information into the system. These individuals must undergo proper training and should update their skills periodically. But, there are some advantages that a company enjoys after successful installation of CIM system; increased production rate, improved products quality, few errors, and creates a platform for mass production (Computer Integrated Manufacturing, 2013). Section E People prefer the cast irons for manufacturing of brake discs. This is because they are readily available at a cheaper price unlike other metals. The cost of production by casting is also cheap compared with other production processes that require a lot of capital (Collini & Nicoletto, 2007, p. 529). Further, individuals are now using the metal matrix composites widely in the production of brakes discs. This is because they are an alternative to conventional materials used in the automotive industry. They facilitate production of brakes discs at a lower cost (Adebisi, 2011, p. 471). Additionally, carbon-carbon composites are mostly recommendable for wear-related applications especially the brake discs of heavy duty vehicles like supersonic, military, and civilian trucks. This minimizes the future maintenance cost; hence the vehicles become more economical to use (Manocha, 2003, p.356). In addition, individuals often prefer carbon-ceramic composites in the production of brake discs for luxury cars such as limousines, and vehicles meant for sports. This is because they are durable and the braking becomes more comfortable. These composites are expensive to deal with, but they are economical since people use them to produce brake discs for expensive cars, hence adding more value to the vehicle (SGL Group Carbon Company, 2013). In conclusion, cast iron, carbon-carbon composites, metal-matrix composites, and carbon-ceramic metals are the most common in the production of brake discs. However, the choice made by the manufacturer depends on the desired properties of the brake discs. Technology is advancing at a very high rate, therefore researchers will discover more materials in future, thus creating a wide variety of materials from which manufacturers can choose from. Reference List Adebisi, A. 2011. Metal matrix composite brake rotor: historical Development and product life cycle analysis, 4, pp. 471-480. Retrieved from umpir.ump.edu.my/.../Metal_Matrix_Composite_Brake_Rotor_Historical. pdf Ashby, M. (2005). Materials selection in mechanical design. Amsterdam Boston: Butterworth- Heinemann. Aran, A. 2007. Manufacturing processes of engineering materials, 1, pp. 1-64. Retrieved from www.pearsonhighered.com/assets/hip/us/hip_us.../0136081681.pdf‎ Bryant, 2013. Brakes. Retrieved from http://web.bryant.edu/~ehu/h364proj/sprg_97/dirksen/brakes.html Chawla, L. 2010. Metal-Matrix Composites, 1, pp. 1-24. emissions.pnnl.gov/meeting/pdf/metal_metrix_composites_dherling.pdf‎ Collini, L. & Nicoletto, G. 2008. Microstructure and mechanical properties of pearlitic gray cast Iron. Retrieved from www.researchgate.net/...Microstructure...properties...gray_cast_iron/.../3...‎ Computer Integrated Manufacturing, 2013. Computer Integrated Manufacturing (CIM). Retrieved from http://www.computerintegratedmanufacturing.com Dsianita, 2013, Flexible Manufacturing Systems (FMS). Retrieved from http://www.uky.edu/~dsianita/611/fms.html Ibrahim, K. 2013. Disc brake, pp 1-20. Retrieved from www.cdxetextbook.com/brakes/brake/disc/discbrakeoperation.html‎ Maleque, A. 2010. Material selection method in design of automotive brake discs, 3, pp. 978- 988. Retrieved from www.iaeng.org/publication/WCE2010/WCE2010_pp2322-2326.pdf‎ Manocha, L. 2003. High performance carbon–carbon composites, 28, pp. 349–358. Retrieved From www.ias.ac.in/sadhana/Pdf2003Apr/Pe1069.pdf‎ Savage, G. (1993). Carbon-carbon composites. London New York: Chapman & Hall. SGL Group Carbon Company, 2013, Carbon-Ceramic Brake Disks. Retrieved from http://www.sglgroup.com/cms/international/products/product-groups/bd/carbon-ceramic- brake-disks/index.html?locale=en Yang, Q. 2000. Phase analysis of carbon-ceramic composites Synthesized by in-situ Sintering, 43, pp. 388-393. Retrieved from www.icdd.com/resources/axa/vol43/v43_054.pdf‎ Read More