1. Process Principles Comparison
| Process |
Pressure Source |
Filling Method |
Typical Pressure Range |
| High Pressure Casting (HPDC) |
Hydraulic or mechanical pressure |
Molten metal injected at high speed |
50~150 MPa |
| Low Pressure Casting (LPDC) |
Compressed gas (inert gas) |
Molten metal fills mold slowly from bottom |
0.01~0.1 MPa |
| Gravity Casting |
Natural gravity (no external pressure) |
Molten metal flows freely into mold |
0 MPa (gravity only) |
2. Process Characteristics Comparison
| Comparison Item |
High Pressure Casting |
Low Pressure Casting |
Gravity Casting |
| Filling Speed |
Very fast (30~60 m/s) |
Relatively slow (0.5~2 m/s) |
Slowest (gravity dependent) |
| Mold Structure |
Complex, must withstand high pressure |
Moderate, with riser tube system |
Simple (sand/metal mold) |
| Production Efficiency |
Very high (for mass production) |
Medium (for medium/small batches) |
Low (for small batches/single pieces) |
| Casting Quality |
Smooth surface but may have pores |
Dense with few pores, better mechanical properties |
Dense structure but rough surface |
| Heat Treatability |
Usually not heat-treatable |
Heat-treatable |
Heat-treatable |
| Cost |
High mold and equipment cost |
Moderate |
Lowest (sand casting is particularly cheap) |
3. Suitable Materials
- High Pressure Casting: Aluminum alloys, magnesium alloys, zinc alloys (mainly low melting point alloys).
- Low Pressure Casting: Aluminum alloys, copper alloys (can also be used for cast iron).
- Gravity Casting: Aluminum alloys, copper alloys, cast iron, cast steel (widest material applicability).
4. Typical Applications
| Process |
Typical Applications |
| High Pressure Casting |
Automotive components (dashboard brackets, housings), 3C product casings |
| Low Pressure Casting |
Automotive wheels, engine cylinder heads, aerospace components |
| Gravity Casting |
Large castings (machine tool bases), artworks, traditional castings |
5. Key Differences Summary
- Pressure and Filling Method
- High Pressure Casting: High pressure and speed, suitable for thin-walled complex parts but prone to porosity.
- Low Pressure Casting: Low pressure and slow filling, smooth filling with few pores, suitable for high-quality castings.
- Gravity Casting: No external pressure, relies on gravity, suitable for thick-walled or large castings.
- Casting Properties
- High Pressure Casting: Good surface quality but potentially porous internally, average mechanical properties.
- Low Pressure Casting: Better mechanical properties, heat-treatable, suitable for load-bearing components.
- Gravity Casting: Dense structure but rough surface, suitable for parts without high precision requirements.
- Economic Considerations
- High Pressure Casting: Expensive equipment, suitable for mass production.
- Low Pressure Casting: Moderate cost, suitable for medium-high quality requirements.
- Gravity Casting: Lowest cost, suitable for small batches or large parts.
How to Choose?
- Choose High Pressure Casting: For mass production, complex thin-walled parts (e.g., automotive components, electronic housings).
- Choose Low Pressure Casting: For medium batches, high-quality requirements (e.g., wheels, engine components).
- Choose Gravity Casting: For small batches, large thick-walled parts (e.g., machine bases, artworks).
Each process has its advantages and disadvantages; selection should be based on material, production volume, cost, and performance requirements.
