Understand the differences between the two processes in detail：

1Step 1: Mold Design (Source of Accuracy)

• Gray cast iron: 0.8-1.0% shrinkage
• Ductile iron: 0.9-1.1% shrinkage
• Cast steel: 1.2-2.0% shrinkage
• Draft angle: 0.5°-3°
• Processing allowance: coated sand 2-5mm; resin sand 5-10mm

2Step 2: Forming Process (Core of Quality)

3Step 3: Smelting & Casting (Performance Assurance)

• Gray iron: C 3.2-3.6%, Si 1.8-2.2%,Mn 0.6-1.0%
• Ductile iron: C 3.6-4.0%, Si 2.2-2.8%, Mg 0.03-0.06%
• Pouring temp: 1380-1420℃ (gray iron); 1420-1460℃ (ductile iron)
• Fluctuation: ±10℃ max

4Step 4: Full-Process Quality Testing

• 3D Scanner: ±0.02mm accuracy
• Metallographic Microscope: 100-1000x
• Ultrasonic Flaw Detection: Φ1mm sensitivity
• Full inspection: mold → first piece → batch → finished product

Choose Coated Sand Shell if:
• Accuracy: CT7-CT9
• Weight ≤200kg
• Annual output ≥500 units
• Complex structure

Choose Resin Sand if:
• Large size & heavy weight
• Small batch / trial production
• Strict cost control required

For customized process design, welcome to contact us for professional support.