Enhancement of surface quality brass castings cost effectively using naturally available sand and clay available in Sri Lanka

Abstract

Through a survey done for the Sri Lankan foundry industry using a structured questionnaire it was revealed that one of the most significant quality parameter of the brass casting is the high surface roughness. Properties of the sand clay- mixture, the gating system of the mould, composition of the material to be melted and pouring temperature are the factors, which affect the surface roughness. Out of these factors the attention was focused in this work to the properties of the sand-clay mixture like fineness no., clay content, moisture content and permeability etc. to reduce the surface roughness. A synthetically unmodified sand-clay mixtures consisting of natural sand and clay from different locations in Sri Lanka were analyzed with respect to the reference sand sample (naturally bonded sand-clay mixture) imported from Japan, which gives a considerably low surface roughness. In this research work the attention was also directed to develop a non-contact method to measure the surface roughness of castings using ultrasonic echo amplitude technique. With this method it is possible to measure the surface roughness of castings with improved accuracy and minimized cost. The results of the experimental work done in this work show that it is possible to produce several number of mixtures made by mixing different sand and clay available in Sri Lanka and those mixtures give a relatively good surface roughness for the brass castings with compared to the casting made with Japanese reference sample.