Strategies to improve quality of gravity die casting for Sn-Pb alloy are outlined here by modifying the mould’s gating system, i.e. mainly the down sprue and the sprue well. Analysis based on the experimental work of 27 casting products delivers a promising result for industrial application. Quantitative analysis of porosity defect in this work was based on density analysis. The investigation of the effect of down sprue design on the casting defects was worked out through the variation of tapered down sprue by one degree and two degrees. From the density analysis, the two degrees tapered down sprue results in then less porosity defect. Meanwhile, the highest density was identified at 50 mm, when radius of the down sprue was investigated at 0 mm, 5 mm and 100 mm. Finally, the investigation for sprue well radius of 0 mm, 50 mm, and 100 mm shows that the best sprue well radius related to the highest metal density occurs at a radius of 50 mm.
