The two main types of die casting are hot chamber die casting and cold chamber die casting, classified based on how molten metal is fed into the die.
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Two Types of Die Casting :
In manufacturing, die casting is mainly classified into two types based on how molten metal is injected into the die. These two types are hot-chamber die casting and cold-chamber die casting.
1. Hot-Chamber Die Casting
Definition
Hot-chamber die casting is a process in which the metal melting furnace is an integral part of the die casting machine, and molten metal is injected directly into the die.
Working Principle
- Metal is melted in a furnace attached to the machine
- A gooseneck mechanism is immersed in molten metal
- A piston pushes molten metal into the die cavity under high pressure
- Metal solidifies quickly
- Die opens and casting is ejected
Suitable Metals
- Zinc alloys (Zamak)
- Magnesium
- Lead and tin alloys
❌ Not suitable for aluminium and copper alloys (they damage the gooseneck)
Advantages
- Very fast cycle time
- High production rate
- Low metal wastage
- Better surface finish
- Less oxidation of molten metal
Disadvantages
- Limited to low-melting-point metals
- Machine cannot handle aluminium or copper
- Smaller casting size
Applications
- Electrical fittings
- Hardware components
- Automotive small parts
- Consumer goods
2. Cold-Chamber Die Casting
Definition
Cold-chamber die casting is a process in which molten metal is melted in a separate furnace and then poured into the shot chamber for injection.
Working Principle
- Metal is melted in a separate furnace
- Molten metal is ladled into the shot sleeve
- A hydraulic piston injects metal into the die under high pressure
- Metal solidifies
- Die opens and casting is removed
Suitable Metals
- Aluminium alloys
- Copper alloys
- Magnesium (sometimes)
Advantages
- Suitable for high-melting-point alloys
- Can produce larger and thicker castings
- Less machine corrosion
Disadvantages
- Slower cycle time than hot-chamber
- More oxidation during transfer
- Higher operating cost
Applications
- Automotive engine components
- Gear housings
- Structural aluminium parts
- Heavy industrial components
3. Comparison Table
| Feature | Hot-Chamber | Cold-Chamber |
|---|---|---|
| Furnace | Built into machine | Separate |
| Injection method | Gooseneck system | Shot sleeve |
| Suitable metals | Zn, Mg, Pb, Sn | Al, Cu, Mg |
| Cycle time | Very fast | Slower |
| Casting size | Small | Medium to large |
| Machine wear | High with Al | Lower |
| Production rate | Very high | High |
4. Summary
- Hot-chamber die casting → fast, efficient, used for low-melting metals
- Cold-chamber die casting → suitable for aluminium and copper alloys, larger parts
Conclusion
The two types of die casting are hot-chamber die casting, used for low-melting-point alloys, and cold-chamber die casting, used for high-melting-point alloys like aluminium and copper.
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