Comprehensive Casting Design Analysis Interactions Between Riser Geometry, Alloy Properties, and Process Conditions

The design of risers in metal casting is a multifactorial optimization problem governed by complex interactions among riser geometry, alloy thermophysical properties, and process boundary conditions. Despite decades of empirical practice, a unified quantitative framework linking these three domains remains elusive, particularly for multi-alloy production environments. This study presents a comprehensive analysis integrating computational solidification simulations (ProCAST v2023.1), statistical design of experiments (DoE), and experimental validation across four commercially relevant alloys: gray cast iron (GCI), ductile iron (DI), aluminium alloy A356, and low-carbon steel (LCS). A full-factorial DoE encompassing riser height-to-diameter ratios (H/D: 0.5–3.0), modulus ratios (Mr/Mc: 1.0–1.6), pouring temperatures (Tpour: Tliq+30°C to Tliq+80°C), and mold preheating levels (25–350°C) was conducted across 288 simulation runs, yielding 1,152 coupled feeding-efficiency and porosity-distribution datasets. Statistical regression models were derived with R² > 0.94 for all alloy-condition combinations. Key findings demonstrate that the optimal riser geometry is strongly alloy-dependent: gray cast iron, exhibiting graphitic expansion, tolerates modulus ratios as low as 1.1, whereas low-carbon steel requires Mr/Mc ≥ 1.45 to suppress centreline shrinkage. For aluminium A356, the H/D ratio emerges as the dominant geometric parameter, with cylindrical risers (H/D = 1.5) reducing porosity volume fraction by 62% compared to flat-topped designs. Interaction effects between pouring temperature and mold preheat are significant (p < 0.01) for all alloys, with combined high-temperature conditions extending the feeding window by 18–34%. The derived regression equations, validated against 36 independent industrial castings (MAE < 4.8%), provide directly applicable design criteria for foundry engineers.