<p>Sand casting is widely used for manufacturing complex metal components, and the design of an effective gating system plays a crucial role in controlling casting defects and improving yield. However, gating system design in sand casting still largely relies on expert judgment and trial-and-error approaches, often resulting in high rejection rates and inefficient production. The objective of this study is to develop a closed-loop simulation-driven framework for gating system design that minimizes human intervention during design iterations. The proposed methodology integrates CAD modeling, commercial casting simulation, and MATLAB-based automation scripts into an iterative closed-loop workflow. Within this framework, critical gating parameters are automatically modified based on melt flow behavior and defect prediction obtained from simulation results until a defect-free configuration is achieved. The framework was validated using a gunmetal wear ring casting in which shrinkage cavity defects were predominant with the existing gating system. Autonomous simulation iterations progressively refined the gating geometry, leading to the elimination of shrinkage defects in simulation, which was subsequently validated through shop-floor casting trials and gamma radiography. Experimental production of 32 wear rings resulted in zero rejection, with casting yield improving from 63.37% to 65%. These results indicate that the proposed framework provides a systematic and simulation-driven approach for gating system design, with the potential to reduce reliance on empirical design practices and physical trial-and-error in sand casting.</p> Graphical Abstract <p></p>