Green Sand Casting – The Backbone of Mass Production

Key Process Steps  

1. Sand Preparation System  

Sand Formula: Quartz sand (AFS 50-60) 85% + bentonite 8% + coal dust 5% + water 2%. Mixing time: 4-6 minutes. Compactness: 85-90 units.  

- Sand Reclamation: Vibratory screening + magnetic separation + baking (750°C) achieves ≥90% sand reuse rate. New sand replenishment ≤5%.  

2. Molding and Closing  

- Mechanical Molding: Japanese Sintokogio static pressure lines (0.8-1.2 MPa) produce 120 molds/hour. Mold hardness ≥85.  

- Hybrid Process: Combines lost foam and sand casting to produce 20-ton machine tool beds with flatness error ≤1.5 mm/m.  

3. Melting and Quality Control  

- Molten Iron Adjustment: Gray iron (HT250) carbon equivalent controlled at CE=3.8-4.1%, with Si content fluctuation ±0.05% via optical emission spectrometry.  

- Pouring Optimization: Bottom-gating system ensures molten metal rise speed of 30-50 mm/s, minimizing slag inclusion.  

Product Performance Data  

- Construction Machinery Parts: QT700-2 ductile iron drive wheels (tensile strength ≥700 MPa). Annual output: 80,000 units, capturing 18% domestic market share.  

- Municipal Components: EN124 standard D400-grade ductile iron manhole covers, load capacity 40 tons, passing 1,000-hour salt spray tests.