Investigation of optimum gating system design of fused deposition modelling pattern for sand casting

Abstract

Sand casting is a process of pouring molten metal into a mould. The quality of the casting highly depends on the pattern and mould involving the gating system design. Inappropriate gating system design leads to casting defects. Moreover, conventional sand casting pattern production is time consuming, expensive and unable to produce complex patterns. This research therefore studies the feasibility of using the Fused Deposition Modelling system as a rapid tooling process to produce a sand casting pattern. To do this, three concepts of the gating system designated by the location and size of sprue and riser were generated using the CAD software. In order to select the optimum gating system design, ANSYS software was employed to analyse the filling process based on eight ranking criteria which included static pressure, density all, velocity magnitude, total temperature, internal energy, turbulent viscosity, wall shear stress and velocity streamline. Based on the simulation results, the concept that comprised of the sprue and riser measured 20 mm diameter and designed on both sides of the hand wheel was selected as the optimum design of the gating system since it scored the highest mark in the eight ranking criteria. Then, the actual casting of the hand wheel was produced. In order to validate the results of the simulation, surface roughness and dimension accuracy were done. The sprue and riser that measured 20 mm in diameter showed smoother texture and this dimension was the closest to the ideal dimension. The results also showed that the sprue and riser located on the top of the connector of the hand wheel demonstrated the worst surface finish and dimensional accuracy due to imbalance between molten metal flow through the sprue and riser.