What is the difference between gravity casting and die casting?
2.1.Summary of different casting methods
| Casting Method | Process | Suitable Material | Precision & Complexity | Production Volume | Tooling Costs |
| Die casting | High-pressure method using a die to force molten metal into a mold | Aluminium, Zinc, Magnesium, Copper, Some alloys | Precise & Complex | High | High (Initial) |
| Gravity casting | Low-pressure method using gravity to fill the mold cavity naturally | Aluminium, Brass, Bronze, and some alloys | Moderate precision | Medium to low | Moderate |
| Sand casting | Mold made of compacted sand (Green sand) with molten metal poured in | Aluminium, Iron, Steel, Bronze, and Brass | Moderate precision | Low to medium | Low |
| Investment casting | Mold made by dipping pattern into a ceramic slurry and then pouring molten metal into the mold | Gold, Silver, Bronze, Stainless Steel, and some alloys | High precision | Low to medium | High (Initial) |
| Centrifugal casting | Molten metal is forced into mold, while the mold is rotated at high speed. | Iron, Steel, Stainless Steel and some alloys | Moderate precision | Low to medium | Low |
| Continuous casting | Molten metal continuously poured into a moving mold | Steel, Copper, Aluminium, Magnesium, Zinc, Tin | Low to moderate | High | Moderate |
2.2 Comparison between die casting and gravity casting
Die casting and gravity casting are both metal casting processes used to create complex metal parts. Both gravity casting and die casting are permanent mould casting using moulds made of steel materials. While they share some similarities, they differ in the way molten metal is introduced into the mold and the forces involved in the process. Gravity casting is a low-pressure process more suited for larger parts and lower production volumes. In gravity casting, molten metal is poured from a crucible into a mould by using the force of gravity, instead of using the pressure from gases, vacuums or centrifugal forces. In contrast, die casting is a high-pressure process suitable for mass production of intricate and precise parts. Die casting relies on pressure to inject molten metal into the mould. This process is the most common approach in permanent mould casting. The choice between these casting methods depends on factors such as the complexity of the part, required precision, production volume, and budget constraints. Here are the key differences between the two:
Die Casting:
1. High-pressure method: Die casting is a high-pressure process where molten metal is forced into a reusable steel mold (called a die) under high pressure. The pressure is maintained until the metal solidifies.
2. Precision and complexity: Die casting is suitable for creating intricate and detailed parts with close tolerances. It is commonly used for mass production of complex components.
3. Tooling costs: The initial tooling costs for die casting can be relatively high due to the complexity of the mold. However, it becomes cost-effective for large production runs.
4. Types of die casting: There are two main types of die casting processes: hot chamber die casting (used for alloys with low melting points like zinc) and cold chamber die casting (used for alloys with high melting points like aluminum and magnesium).
Gravity Casting:
1. Low-pressure method: Gravity casting (also known as permanent mold casting) is a low-pressure process where molten metal is poured into a metal mold using gravity alone. The metal is allowed to flow into the mold cavity naturally.
2. Simplicity and lower cost: Gravity casting is a simpler and more cost-effective process compared to die casting. It is suitable for producing larger parts and lower quantities.
3. Less intricate parts: While gravity casting can still produce detailed parts, it may not be as precise as die casting, and tolerances may be slightly looser.
4. Mould material: The mold used in gravity casting is typically made of steel or cast iron and can be used for multiple casting cycles before replacement.
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