Large-scale integral hydraulic multi-way valves in engineering machinery feature complex internal channels and numerous overhanging structures with interconnected oil passages, posing significant demands on sand core strength during casting. Traditional manufacturing techniques achieve a casting success rate of only about 60%, presenting substantial challenges such as high mold costs and lengthy processing cycles, hindering rapid product launch. Three-dimensional (3D) printing technology offers several potential solutions. Recent studies by domestic and international researchers have successfully applied selective laser sintering (SLS) and binder jetting (3DP, PCM) technologies to relatively simple structural components such as casings, boxes, and cylinder bodies. However, successful instances of rapid manufacturing of hydraulic valves are scarce. Owing to inherent weaknesses in the strength and density of 3D-printed sand cores, the rapid casting of large, complex internal cavity-structured integral multi-way valves using 3D printing remains problematic, with a casting success rate below 60%. Furthermore, research and applications in this field are limited. Therefore, there is an urgent need to develop rapid manufacturing technologies for integral hydraulic multi-way valves based on sand mold 3D printing, aiming to advance sand mold additive technology in engineering machinery, equipment manufacturing, aerospace, and other fields.

This study conducted a comparative analysis of the performance of two typical 3D printing processes for rapid sand mold manufacturing to identify the most suitable 3D printing technology for integral hydraulic multi-way valves. Focusing on a representative integral hydraulic multi-way valve, the research examined its structural characteristics and casting challenges through failure case analysis. Using finite element simulations, the filling processes of single-layer and composite casting systems were investigated by comparing metal flow velocity during mold filling. Based on these analyses, a composite casting system was developed specifically for 3D printing applications. Additionally, exhaust systems were designed for both internal sand cores and external molds, incorporating reinforced core and high-temperature-resistant coating. Finally, rapid casting experiments and mass production verification were conducted for integral hydraulic multi-way valves.

A rapid casting solution for 3D-printed integral hydraulic multi-way valves was developed, incorporating a “composite casting system, conformal exhaust, strength enhancement, and temperature-resistant coating” approach. Through rapid casting and testing verification, the results demonstrate that the integral multi-way valve exhibits good overall forming quality, with well-formed internal oil passages showing a straightness of ≤0.28 mm/100 mm. Internal inspection of sectioned valve bodies reveals no defects such as pores or flash with dimensions ≥0.3 mm. The average hardness deviation within the valve body is ≤5%, confirming the feasibility of rapid casting for large-scale integral hydraulic multi-way valves using 3D printing technology.

A comparative analysis of different 3D printing technologies, including selective laser sintering (SLS) and binder jetting (3DP), was conducted to evaluate sand mold properties such as strength, printing accuracy, and gas evolution rate. The results indicate that 3DP sand mold printing technology is more suitable for the rapid casting of large-scale integral multi-way valves. By comparing metal flow velocity in single-layer and composite casting systems, a composite casting system for integral hydraulic multi-way valves was developed based on 3D printing technology. This system leverages the advantages of single-layer casting while preventing continuous impact on local sand cores, thereby improving casting success rates. A performance enhancement method for 3D-printed sand cores was proposed, incorporating “conformal exhaust, strength enhancement, and temperature-resistant coating,” which increases overall bending strength and effectively prevents internal defects in valve bodies. The developed rapid casting process successfully produces integral hydraulic multi-way valves, with CT scans showing no casting defects such as shrinkage cavities or porosity exceeding the specified size limits. The valve body exhibits uniform and stable internal hardness, meeting industrial application requirements. The technical achievements of this research demonstrate the feasibility of mass production and provide a foundation for the rapid manufacturing of large components with complex internal structures.