Impact of Moisture Variationon Some Foundry Properties of Fori Silica Sand

Abstract

Moulding Sand for metal casting is usually sourced from either natural deposit or synthetic mix of refractory sand grain binder and moisture. Each of the mix constituent is important in determining the characteristics of sand. The binding agent is responsible for bendability thereby determining the size of voids within the sand grain, while moisture level determines the plasticity of the foundry sand. Tests using American Foundry Society (AFS) Standard were followed in carrying out the experiment on Fori sand deposit to determine its suitability for foundry use. The sand was collected from the river bank of Fori, in Fori Community, Maiduguri, Borno State. The experimental test equipment includes: laboratory sand mixer, sand rammer, universal strength testing machine, permeability-meter, oven, mouldability machine, and as well as quick moisture teller. The chemical composition of the materials was carried out using atomic absorption spectrophotometer (AAS) model PG990AFG. The silica content in the material sample is about 78.65%, and with the traces of other elements, such as CaO (1.07%), Fe2O3 (0.76%), Al2O3 (15.81%), MgO (1.01%), TiO2 (2.21%), K2O (3.87%), and Na2O (1.16%), respectively. These percentages are within acceptable limits. The results of the physical properties revealed that the sand sample has clay content of 15.32% which is above the standard range of 10% - 12% recommended for natural moulding sands required for producing good quality castings. Other foundry properties of Forinatural moulding sand conducted include “moisture content” in the following ranges of percentages, 7.6%, 6.5%, 5.8%, 4.2% and 2.9% with the corresponding value of green compressive strength of (43.95, 53.47, 69.56, 68.21 and 61.16 KN/m2), dry compressive strength (93.50, 96.52, 105.50, 146.50 and 152.49 KN/m2), and permeability No. of 340, 390, 410, 430 and 440 respectively. It is clear from the test that, the lower the moisture content, the higher the dry compressive strength of the materials. The refractoriness value of the materials is 1400 ℃. The results of the physical and other foundry properties carried out show that Forisilica sand is suitable for casting non-ferrous alloys like bronze, brass and aluminium, and cast iron.