Abstract: In this paper, aluminium blank green sand (green) casting process was optimized by using Taguchi's robust design approach. An attempt was made to obtain optimal settings of two groups of aluminium blank sand casting processes. Single aluminium blank sand casting and double aluminium blanks sand casting for process robustness comparison. The casting process involves a number of parameters affecting various casting quality features of the product. In order to optimize the process seven control factors viz., grain size, clay content, moisture content, ramming, sprue size, riser size, and diameter to thickness (D/t) ratio of the blank were selected. Each factor was considered at three levels. For this study three uncontrollable (or noise) factors viz. metal flow rate, pouring temperature and humidity were identified. To capture the effect of noise factors casting yield, surface defects, and casting density for single and double castings were measured. An orthogonal array was constructed for the seven factors undertaken, and performing eighteen sets of experiments with their replicates generated the data. The signal-to-noise (S/N) ratio s were calculated based on the design of experiments. The average values of S/N ratios for each factor at three levels were calculated and were plotted on the graph. Considering the maximum S/N ratios from the graph, the optimum levels of process factors for both single and double castings were obtained. A statistical analysis of variance (ANOVA) was performed to see which process parameters are statistically significant. A verification experiment was performed using the identified optimum conditions. The results have shown that single aluminium blanks and casting process is more robust than double aluminium blank sand casting process. This proved that single aluminium blank sand casting process had shown better insensitivity to noise factors. The experimental results confirmed the validity of used Taguchi robust design method for enhancing sand casting process and optimizing the sand casting parameters in aluminium blank casting process.
Keywords: Optimization, Sand casting process, Taguchi method, Aluminium-blank, Signal-to-noise ratio, Analysis of variance, Orthogonal array
Recieved: 20.09.2011 Accepted: 15.01.2012 UDC: 669.716