Natural Honey and Nigerian Gum Arabic as Composite Binder for Expendable Foundry Cores

Abstract

Potentials of foundry sand core binders made with composites of Nigerian gum Arabic and natural honey were investigated. Core specimens made with silica base sand bonded with composites of each of four grades of Nigerian gum Arabic and honey were classified and tested for tensile and compressive strength; permeability and shatter index to ascertain binder efficacy. Tensile strength specimens shaped like figure number eight were oven baked at 180°C and 200°C; cooled to room temperature and tested with universal strength machine. Cylindrically shaped permeability and shatter index specimens were tested with permeability meter and shatter machine. Results showed that cores baked at 200°C attained higher strength at shorter baking periods than those baked at 180°C. Honey improved tensile strength by 15%, 17%, 16% and 17% over the plain gum Arabic grades 1, 2, 3, 4 bonded cores, respectively. It improved compressive strength by 7%; permeability and shatter index by 2%. Composites cores of 3% gum Arabic grade 2 - 4 with 0.5% honey baked at 200°C were suitable for magnesium, copper bronze, non-intricate aluminium, classes III, IV, V iron and steel castings. Cores made with composites of 1.5 - 3% honey and 3% gum Arabic grade 1 - 4 were suitable for intricate aluminium, copper brass, class II - V iron and steel castings.