Properties of Grey Cast Iron and Why It Is Used in Making Disc Brake - Coursework Example

Disc Brake Name Institution Date Course Properties of grey cast iron and why it is used in making disc brake The role of brake disc is to react with the brake pads in order to convert, by means of friction, the kinetic energy of motion into thermal energy or heat. The weight and speed of the vehicle determines the amount f heat that can be produced. In most cases, an excess of 500 degrees centigrade has to be produced (Kathiresan, et al, 2014). The material for disc brake must therefore have high thermal stress resistance characteristics. The grey cast iron has good thermal conductivity and diffusibility characteristics. This is an important property that has greatly contributed to its use. The thermal conductivity of grey cast iron is however varied depending on its grade. The material is also clarified as having low to medium strength which is a property required of a disc brake. The grey cast iron material is resistant to distortion and cracking which plays an important role in enabling it to be used effectively for the disc brake. The type of alloy added play an influential role in determining the mechanical as well as the physical properties. Increasing the carbon content improves on the machinability of the material and hence making it easy to use in the manufacture of the disc brake (Kathiresan, et al, 2014). The grey cast iron has generally good abilities that enable it to with stand corrosion. The use of grey cast iron ensures that squeal and groan is reduced due to its mechanical as well as physical properties. The material is also cheap and this makes it easy for the mass production of disc brake. Manufacturing process The hot isotatic pressing of graphite alloy powder is the method that is used during the manufacturing process. This manufacturing route is preferred due to its leaner and shorter than usual conventional metallurgy process. The use of this manufacturing route is also considered as a high cost effective solution. The cost of hot isotatic pressing relative to energy and material cost is decrease by 65% through the use of this manufacturing process (Sołek & Trębacz, 2012). This method is effective in the process of ensuring that the appropriate modifications are done in order to meet the required standards for the disc brake. Modifications carried out through the use of this method are also useful in ensuring the required hardness as well as the strength is attained. The component quality and performance is enhanced through the use of hot isotatic pressing (Rywotycki, et al, 2012). This is an indication that the method is effective in ensuring that the required standards are met. The use of the method ensures that fine and isotropic microstructures are produced. This ensures that near net shapes or net shapes of bimetal construction is attained during the manufacturing process (Lopez, et al, 2014). The production lean times are much shorter when this method of manufacturing is used which is a further indication of efficiency. The densification of the cast parts is usually required during the manufacturing process as a measure of improving on the strength of the material. The process of densification can be varied out effectively through the use of hot isotatic pressing of graphite. Experimental procedure Material used The material for the experiment is grey cast iron that is commonly used in the process of developing the disc brake. The selection of the material is due to its superior qualities when used in the disc brake. Heat treatment practices The heat treatment practices are not commonly used on a commercial scale although it is useful during the experiment. The heat treatment practice alters the microstructure although it does not have much effect on the size and shape of the graphite achieved during casting (Sołek & Trębacz, 2012). The heat treatment of the material is useful during the process of hardening and increasing the overall strength. Resistance to wear and abrasion is increased during the heat treatment process. This process is however expensive and other cheaper methods are used for commercial process. Thermal conductivity examination The thermal conductivity is first examined by determining the graphite morphologies that are present in the cast Iron. During the experiment, heating of the material has to be carried out in order to determine the thermal conductivity. The material has to be heated until a temperature of 300 degrees centigrade is attained (Lopez, et al, 2014). The thermal conductivity can be determined at 300 degrees centigrade. Further heating can then be carried out until the material cracks. The thermal conductivity can then be determined at the point at which the material breaks. Mechanical properties examination The mechanical properties of the material can be determined through the examination of the physical as well as chemical characteristics. A material has to be subjected to pressure in order to determine the point at which it cracks or distorts (Strauss, 2013). This is an important aspect that determines the properties such as brittleness and hardness of the material. Changes to the tensile strength are also an important aspect that is involved during the examination. The hardness of the material is determined with the changes in the tensile strength. Environmental impacts The mining of graphite which is used in the development of the grey cast iron has some negative impacts on the environment. The effects involve pollution through the production of dust as well as other forms of pollutants (Rywotycki, et al, 2012). The casting process equally pollutes the environment through the release of dust from the powder produced during the process. A lot of heat is also produced during the melting process and this may also impact negatively on the environment. The machining process also impacts negatively on the environment as it results to the generation of waste products. A high amount of waste material that may no longer be useable is produced during the machining (Sołek & Trębacz, 2012). Poor disposal of the materials contribute to negative environmental effects. Several measures can however be put in place in order to mitigate the negative environmental effects. The environmental impacts can be reduced during the casting method during the use of specially adapted conveyors. This method involves the machine swarfing process where the chips are collected and conveyed away from the machine tools (Strauss, 2013). Other waste materials such as the cutting fluids are also recovered during the process and hence mitigating the negative environmental effects. This method ensures that all the unwanted parts during the manufacturing process are recovered and properly disposed. Swarfing is thus an important in the management of the wastes. End of Life (EOL) is the final stages of the product (Strauss, 2013). During the final stages of the product, poor disposal is common and it contributes to environmental pollution. To mitigate the environmental pollution as a result of the poor disposal, the manufacturers can collect the products that have reached the end of the lifecycle. Collecting and recycling the products after its use can mitigate the environmental effects. Microstructure related to the manufacturing process and property requirements The microstructure plays an important role in ensuring that the desired properties are obtained. The chemical composition required to obtain the material involves 2.5-4.0% carbon, 1-3% silicon and 6-10% graphite is also required (Rywotycki, et al, 2012). Silicon plays an essential role in the production process of the material. Silicon is used as a graphite stabilizing element. In order to ensure that the required microstructure is obtained, a slower cooling rate has to be utilized. A slower cooling rate allows the carbon to diffuse and accumulate into graphite. The material also takes the shape of a three dimensional flake. The graphite appears as fine lines when observed in two dimensions. Graphite does not have appreciable strength, as a result of this; it can be treated as voids. The presence of graphite in the microstructure makes the material easily machinable (Lopez, et al, 2014). The ease in machinability is useful in ensuring that it can easily be used in the manufacture of the disc brakes. The microstructure of the material also provides it with a good damping capacity which is a property that is required for a disc brake material. Bibliography Kathiresan, K., et al, 2014. Experimental investigation on droplet cooling of brakes. In applied Mechanics and Materials (Vol. 592, pp. 1585-1589). Trans Tech Publications. Sołek, K, & Trębacz, L, 2012, Thermo-Mechanical model of steel continuous casting process, Archives of Metallurgy and Materials, 57(1), 355-361. Lopez, P, et al, 2014, Recent Developments of a Numerical Model for Continuous Casting of Steel: Model Theory, Setup and Comparison to Physical Modelling with Liquid Metal, ISIJ international, 54(2), 342-350. Strauss, K, 2013, Applied science in the casting of metals, Elsevier. Rywotycki, M, et al, 2012, Identification of the boundary conditions in the continuous casting of steel, Archives of Metallurgy and Materials, 57(1), 385-393. Read More