DETERMINATION OF THE OPTIMAL MOISTURE CONTENT FOR EXPENDABLE FOUNDRY SAND CORES BONDED WITH NIGERIAN ACACIA SPECIES
Publication Date : 01/08/2010
The optimum moisture content of oven baked sand cores bonded with Nigerian acacia species was determined for best casting result in this study. Each of the four grades of acacia species exudates produced in Nigeria was used to bind foundry sand cores with moisture varied from 1% to 8%. The specimens were oven baked at 2000C for 1-3 hours, cooled and tested for gas permeability and tensile strength using standard permeability and universal strength machines to measure the effects of differing amounts of moisture in expendable foundry sand cores. It was observed that baked tensile strength increased from 1%-3% added water and thereafter decreased continuously to the lowest value at 8% of added water. The effect was most serious with grade 2 acacia bonded cores followed by the grade 3, grade 1 and grade 4 cores in that order. The result showed that 2-3% moisture content was optimum for cores. For best results it is thus advised that water added to sand cores bonded with Nigerian acacia be 3-4% to achieve this composition. The permeability of tested specimens is sufficient for this optimum range of moisture for sand casting different alloys.
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