An Experimental Investigation of Wax Pattern in Investment Casting

Investment casting process used for precision component manufacture, call for accurate method design. It gives good surface finish and high dimensional accuracy with complex shape. This is the main reason that it is also called as the precision casting. The important factor in the investment casting is the dimensional change of the wax pattern. Dimensional changes between a die and its wax pattern occur as a result of complex phenomena such as thermal expansion-contraction and hot deformation. Due to these defects in the wax patterns, it results into the poor quality of the final casting product. Some common defects are shrinkage, inadequate surface finish, and improper dimensional accuracy in the wax patterns. So there is need to remove these defects.

The following parameters like injection temperature, die temperature and holding time affect the wax pattern. The purpose of the present study is to optimize these parameters using Taguchi's method and experimentally investigate the wax pattern for the investment casting process. Starting from the identification of the different waxes with ten different compositions of samples was prepared by mixing the waxes together for pattern making. Measurement of the volumetric shrinkage as well as the linear shrinkage helped in calculating the dimensional tolerances of the cast component.

After conducting the experiment it was analyzed that wax can be used as a low cost wax pattern. The sample with proportion of 80% paraffin wax, 5% bee wax, 5% Montan wax, 5% carnauba wax and 5% china wax will gives the better result of linear shrinkage as well as volumetric shrinkage.