砂型鋳造は複雑な内外形状をどのように実現しますか？

Mold Cavity and Cores: The Key to Complexity

Sand casting manages intricate geometries by using a disposable mold. The external shape of a part is defined by the cavity within the assembled sand mold, which is created using a pattern. For complex internal geometries—such as hollow sections, undercuts, and internal passages—separate sand cores are used. These cores are pre-formed shapes made of bonded sand and inserted into the mold cavity before pouring. Molten metal flows around these cores, forming the internal features once the cores are broken out and removed after solidification. This technique enables the production of complex parts like engine blocks with water jackets and detailed manifolds.

Versatility in Core Creation and Placement

Creating highly complex cores is a major advantage of modern sand casting. Traditional methods employ core boxes to form cores, but in Rapid Prototyping applications, cores can be directly 3D-printed from sand. This additive approach removes the need for core boxes, allowing internal geometries that are impossible or cost-prohibitive with traditional tooling. Multiple cores can be integrated within a single mold, enabling exceptionally complex internal networks and granting designers greater flexibility.

Design Considerations and Limitations

Despite its versatility, sand casting requires adherence to certain design rules to ensure success. Features must include draft (a slight taper) for easy removal of patterns and cores without breaking the sand. Wall thickness should be as uniform as possible to avoid defects like shrinkage porosity. Extremely fine details, sharp corners, or very thin walls may be challenging and might necessitate alternative processes or subsequent Post Machining. Early collaboration with our die castings Engineering team is essential to optimize design and ensure manufacturability.