Mold Cost and Complexity
Permanent Mold Casting: High initial cost for metal molds (e.g., steel or iron), making it uneconomical for small production runs.
Sand Casting: Lower mold costs but limited reusability, requiring frequent mold replacement for large batches.
Production Speed
Slower cycle times compared to high-pressure die casting (HPDC) due to reliance on gravity for metal filling and natural cooling. Automation can improve speed but adds cost.
Material Restrictions
Unsuitable for metals with very high melting points (e.g., steel, titanium) as repeated exposure to extreme heat degrades molds. Primarily used for aluminum, magnesium, zinc, and copper alloys.
Surface Finish and Dimensional Accuracy
Surface quality is inferior to HPDC, often requiring post-casting machining.
Dimensional tolerances are less precise, especially for intricate geometries.
Part Complexity
Limited ability to cast thin walls or highly complex shapes due to restricted metal flow and solidification control. Undercuts and fine details may require additional cores or post-processing.
Porosity and Defects
Higher risk of gas entrapment, shrinkage cavities, and porosity compared to vacuum-assisted or pressure-based methods. This affects mechanical properties and may necessitate X-ray inspection or heat treatment.
Labor and Skill Dependency
Manual processes (e.g., mold preparation, pouring) increase labor costs and variability. Skilled technicians are needed to minimize defects.
Size Limitations
Large or heavy parts may be challenging due to mold handling constraints and uneven cooling rates, leading to internal stresses.
Applications Where Gravity Casting Excels:
Despite limitations, it remains cost-effective for medium-volume runs of simple to moderately complex parts (e.g., automotive components, cookware) where surface finish and precision are secondary to cost and material properties.
Conclusion: Gravity casting balances cost and performance but is less suitable for high-volume, high-precision, or ultra-complex parts compared to advanced methods like HPDC or investment casting.
