What is the difference between PDC and GDC?

PDC (Pressure Die Casting) and GDC (Gravity Die Casting) are two common aluminum casting processes, differing in filling method, equipment, and application — here’s a detailed comparison:
Filling Method: PDC uses high pressure (10–150 MPa) and high speed (10–50 m/s) to inject molten metal into the die; GDC relies ongravity alone (no external pressure) to fill the mold, with a slow filling speed (0.1–0.3 m/s).
Production Efficiency: PDC is much faster (cycle time 10–60 seconds per piece, daily output up to 10,000 pieces) for mass production; GDC is slower (cycle time 2–5 minutes per piece, daily output up to 500 pieces) for medium batches.
Part Quality: PDC offers higher precision (tolerance IT8–IT10, surface roughness Ra 0.8–1.6 μm) but may have internal porosity; GDC has better internal density (porosity rate ≤1%) and is more suitable for heat treatment, with slightly lower precision (tolerance CT7–CT10, Ra 1.6–3.2 μm).
Cost: PDC has higher initial tooling costs (30–50% more than GDC) but lower unit costs for large batches; GDC has lower mold costs, making it ideal for small to medium batches (500–10,000 pieces).
Applications: PDC for high-volume, small-to-medium complex parts (e.g., electronic housings, automotive parts); GDC for thick-walled, high-strength parts (e.g., engine blocks, hydraulic components).