Design of Tapered Riser Using Basic Hydraulic Principles

Abstract

In sand casting, the design of gating and riser system plays an important role in the quality of the casting. Poor designs of these two parameters lead to major defects such as incomplete filling, porosity, and re-oxidation inclusions. These defects cause the castings to be susceptible to failure during their use. A riser system with high volume to surface area ratio gives a sound casting. The conventional casting setup used in many foundries incorporates the use of cylindrical risers. Improvement of the gating and riser system by use of computational analysis was carried out. Through several computational analyses, it was concluded that a casting with minimal defects could be obtained by modifying a cylindrical riser to form a tapered riser which has a higher volume to surface area ratio.