DEPARTMENT OF MECHANICAL ENGINEERING
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Item Taguchi optimization of process parameters on the hardness and impact energy of aluminium alloy sand castings(2013) Oji, J. O.; Sunday, P. H.; Petinrin, O. M.; Adetunji, A. R.An optimization technique for sand casting process parameters based on the Taguchi method is reported in this paper. While keeping other casting parameters constant, aluminium alloy castings were prepared by sand casting technique using three different parameters, namely the mould temperature, pouring temperature and runner size. Hardness and impact energy tests were done for the resulted castings. The settings of parameters were determined by using the Taguchi experimental design method. The level of importance of the parameters on the hardness impact energy was determined using the analysis of variance (ANOVA). The optimum parameter combination was obtained by using the analysis of signal-to-noise (S/N) ratio. Analysis of the results shows that 100°C mould temperature and 700°C pouring temperatures are optimal values for hardness and impact energy. However 200 mm2 and 285 mm2 runner sizes are the optimal values for hardness and impact energy respectively. The mould temperature was the most influential parameter on the hardness impact energy of the castings.Item Effect of silicon content and shake-out time on hardness and grain size properties of GL 250 cast iron(2011) Atanda, P.; Oluwadare, G.; Oluwole, O."The properties of cast iron grade GL 250 are dependent on the microstructures developed during casting. These microstructures are in turn dependent on the composition of the alloy, type of mould and other numerous casting practice variables such as shake-out time, pouring temperature, mould ambient conditions and inoculating technique. In this work, the effect of silicon content and shake-out time on the grain size (GS) and hardness properties of GL 250 cast iron was studied using a pouring temperature of 14000C and sand mould casting. Using charge materials consisting of pig iron and other additives, GL 250castings containing silicon contents of 1.7, 2.1 and 2.7% were casted using a constant pouring temperature of 14000C, molding sand of specified properties and ambient mould temperature of 320C. Results showed that type A flake type was obtained at 30mins shakeout time for all samples for the C.I composition under study. Increasing shake-out time decreased hardness and increased carbide grain size. Increasing silicon content was observed to increase grain size and reduce free graphite but with resultant decrease in hardness. Two mathematical relationships were derived. One related grain-size to silicon content and shakeout time while the second related Brinnel Hardness to Silicon content and shake-out time. They are: Grain Size=0.40 Si+0.17Shake-out Time-0.15 and BHN=-60.53Si-7.15Shake-out Time+329.35 at 14000C pouring temperature in a molding sand of specified properties and sand mould ambient temperature of 320C. "Item Effect of silicon content and shake-out time on hardness and grain size properties of GL 250 cast iron(2011) Atanda, P.; Oluwadare, G.; Oluwole, O."The properties of cast iron grade GL 250 are dependent on the microstructures developed during casting. These microstructures are in turn dependent on the composition of the alloy, type of mould and other numerous casting practice variables such as shake-out time, pouring temperature, mould ambient conditions and inoculating technique. In this work, the effect of silicon content and shake-out time on the grain size (GS) and hardness properties of GL 250 cast iron was studied using a pouring temperature of 14000C and sand mould casting. Using charge materials consisting of pig iron and other additives, GL 250castings containing silicon contents of 1.7, 2.1 and 2.7% were casted using a constant pouring temperature of 14000C, molding sand of specified properties and ambient mould temperature of 320C. Results showed that type A flake type was obtained at 30mins shakeout time for all samples for the C.I composition under study. Increasing shake-out time decreased hardness and increased carbide grain size. Increasing silicon content was observed to increase grain size and reduce free graphite but with resultant decrease in hardness. Two mathematical relationships were derived. One related grain-size to silicon content and shakeout time while the second related Brinnel Hardness to Silicon content and shake-out time. They are: Grain Size=0.40 Si+0.17Shake-out Time-0.15 and BHN=-60.53Si-7.15Shake-out Time+329.35 at 14000C pouring temperature in a molding sand of specified properties and sand mould ambient temperature of 320C. "Item Effect of soaking time on the machinical properties of anealed cold-drawn low carbon steel(Scientific Research, 2012-08) Raji, N. A.; Oluwole, O. O.The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% deformation was annealed at 900 deg Celsius for soaking times of 10, 20, 30, 40, 50 and 60 minutes. Tensile, charpy and Brinnel hardness tests were conducted to determine the yield strengths, tensile strengths, impact strengths, ductility and hardness of the an- nealed steel with increasing soaking time. The yield strength, tensile strength, hardness and impact strength of the steel showed a continuous drop in value with increasing soaking time up to 60 minutes with a steep drop between 30 and 40 minutes. Ductility values followed the same decreasing trend up to 40 minutes soaking time after which the values started increasing again till 60 minutes soaking time. There was a linear relationship between the tensile strength and hardness of the material for different soaking times. This linear relationship was also observed for yield strength and hardness of the material.