Experimental Investigation of Wax Blends in Investment Casting Process

摘要

The objective of this paper is to determine the accuracy of patterns produced from different blends of wax (paraffin, bees, carnauba and montan waxes) and to investigate their suitability for investment casting with special reference to thermal expansion properties. For general characterisation of waxes, Differential Thermal Analysis (DTA) was carried out. Several patterns were produced by keeping injection parameters constant. Linear and volumetric contraction of wax patterns was measured. Root Mean Square (RMS) values and dimensional variation were also determined. Volumetric coefficient of thermal expansion of the wax blends was experimentally calculated. It has been shown that the accuracy of patterns from all blends is not consistent. However, patterns produced using paraffin wax: bees wax: montan wax in the ratios 50 : 30 : 20 respectively had much less contraction (0.89%) as compared to other blends (1.05 to 2.99%). Both linear and volumetric contraction data would greatly assist in achieving improved dimensional control and reduced lead time through an improved data input at the die design stage.