Influence of injection process parameters on dimensional stability of wax patterns made by the lost wax process using Taguchi approach

Abstract

Investment casting is a manufacturing technique employed to produce near net shape metal components. Wax is the most widely used pattern material. In the present work, the wax blend, to be used in the investment casting process, is prepared by mixing different waxes and starch as filler material to reduce the shrinkage of wax patterns. The effect of the selected injection process parameters on the dimensional stability of the wax patterns made by the investment casting process using silicon rubber mould has been studied and the optimum injection process parameters to reduce the shrinkage of wax patterns have been suggested. The wax injection processing parameters considered for experimentation were injection temperature, injection pressure and injection time. Taguchi's L9 orthogonal array was used for designing the experiments. The signal-to-noise and the analysis of variance were used to find the optimum levels and to indicate the impact of the process parameters on shrinkage of wax patterns. The confirmation tests were conducted and the results were found to be within the confidence interval. The analysis of experimental results showed that the injection temperature and injection pressure greatly influenced the dimensional stability of wax patterns.