littleStudy On The Shear Strength Of Foundry Sand Cores Using Clay And Cassava Starch As Binder

Abstract

Sand cores for casting intricate shapes were produced from Ojolofe silica sand using cassava starch and Iyoloko clay, Idah Kogi State Nigeria as binders. Various compositions (6 – 12% water 4 – 12% cassava starch and 5% Iyoloko clay) and Ojolofe silica sand were mixed to produce standard cores samples of two different types (green and baked). Cores samples were baked at different temperatures ranging from 90 and 200oC for 60 – 150 minutes. Determination of shear strengths was carried out on a large number of green and baked cores samples. Appropriate baking conditions and optimum core mixtures were established for cassava starch/clay bonded cores at 180oC and 2 hours respectively; and clay addition was found to increase both the green and baked strengths values. The optimum clay/starch core mixture with the best shear strength values was found to be core produced with 10% starch, 10% water and 5% clay. Their green and baked shear strength values were 31.1 KN/m2 and 498.1 KN/m2 respectively. These values were found to be adequate for production of strong sand cores using starch/clay as binders for non-ferrous and ferrous castings as collaborated by successfully casting of a T – joint pipe aluminum casting.