What are the main aluminum casting methods?
Sand casting is the most versatile, using expendable molds for complex shapes. Die casting employs reusable steel molds for high-volume production. Permanent mold casting balances cost and precision for medium batches. Investment casting achieves fine details with wax patterns. Continuous casting produces long slabs or rods for further processing.
Why is die casting preferred for automotive parts?
It achieves tolerances of ±0.1mm for engine components. Cycle times under 60 seconds enable mass production. High pressure (10-200 MPa) ensures dense, pore-free structures. Alloys like A380 optimize fluidity and strength. Thin walls (1-3mm) reduce vehicle weight without sacrificing durability.
How does sand casting handle large aluminum parts?
Molds can weigh tons for ship propellers or turbine housings. Binders (clay/resin) stabilize sand for geometries >5m long. Chill zones control solidification to prevent defects. Post-casting machining removes rough surfaces (±2mm tolerance). It's 50% cheaper than die casting for prototypes.
What are the challenges in aluminum investment casting?
Wax pattern removal requires precise thermal cycles. Ceramic shells may crack during molten aluminum pouring (660-760°C). Surface finish reaches Ra 1.6μm but adds 30% cost. Limited to parts under 50kg due to mold strength. Aerospace blades need HIP treatment for fatigue resistance.
How does low-pressure casting improve quality?
Controlled argon pressure (0.5-1 bar) minimizes turbulence. Directional solidification reduces shrinkage porosity. Yield rates exceed 90% versus 70% in gravity casting. Wheel hubs achieve 15% higher ductility. Automated systems produce 200+ parts/day with consistent density.
