Differences between Sand Casting and Special Casting

Sand Casting utilizes natural sand (e.g., silica) and binders (clay, resin, etc.) as mold materials. Its core strength lies in exceptional adaptability: it accommodates castings of almost any size (up to hundred-ton parts), material (ferrous/non-ferrous), or batch size, with low pattern costs (wooden patterns) and high scrap metal reuse rates. However, drawbacks include rough surfaces (Ra 12.5–50μm), low dimensional accuracy (CT10-13), and destructive mold removal leading to low efficiency. Key safety risks involve silica dust (silicosis), resin gases (formaldehyde poisoning), and mold collapse. Current innovations focus on green manufacturing (water-based coatings reducing VOCs) and smart foundries (3D-printed sand molds).

Special Casting encompasses 15+ methods (e.g., investment casting, die casting) that revolutionize mold materials and processes. Shared advantages include precision and efficiency breakthroughs:

Material advances: Metal molds (reusable alloy dies) enable high-repeatability casting; investment casting replaces sand with ceramic shells, achieving smooth surfaces (Ra 1.6–6.3μm);

Process enhancements: Pressure casting fills molds at 5–150MPa, boosting productivity 50-fold; centrifugal force densifies tubular parts without porosity;

Performance gains: Mechanical properties improve by >20%, with machining allowances reduced by 30–50%.

Limitations involve high equipment costs (e.g., million-dollar die-casting machines), material restrictions (e.g., metal molds unsuitable for steel), and design constraints (e.g., thick walls in pressure casting). Safety hazards include shell-making dust explosions (investment casting) and molten metal splashing (centrifugal casting). Future R&D targets hybrid molds (ceramic-metal composites) and micro-casting nanoscale precision.

Selection Guidelines:

Sand casting excels for prototypes, oversized/heavy parts (>1 ton), high-melting-point alloys (e.g., steel), and low-budget projects;

Special casting suits mass production (>5,000 units), thin-wall complexity (e.g., automotive parts), and high-accuracy needs (e.g., surgical tools).

Industry evolution must balance accuracy, cost, and safety, avoiding over-prioritizing performance without process compatibility assessment.