Differences and characteristics of aluminum alloy pressure casting and gravity casting

Aluminum alloy is widely used in automobile manufacturing, aerospace, ship and other fields due to its good plasticity, corrosion and light weight. With the development of China's manufacturing industry, the demand for aluminum alloy and aluminum alloy castings is increasing, which will promote the development of aluminum alloy casting industry. At present, the casting method of aluminum alloy is divided into two types: pressure casting and gravity casting. The differences and characteristics of the aluminum alloy pressure casting and gravity casting will be analyzed in detail in this paper.

Aluminum alloy pressure casting refers to the injection molding process under the action of other external forces (excluding gravity). The pressure casting is divided into high-pressure casting and low-pressure casting.

High-pressure casting is usually the die-casting that we say, the aluminum liquid is poured into the pressure chamber, through its pressure high speed fills the mold cavity, and causes the aluminum liquid to solidify under pressure to form aluminum casting.

The characteristics of aluminum alloy die casting are:

Good product surface finish which an generally reach Ra6.3 and even reach Ra1.6.

Heat treatment is not available.

The product has high air tightness, casting strength and surface hardness, but low elongation.

High mold cost and short service life.

High production efficiency.

Thin wall thickness and small machining allowance.

Aluminum alloy gravity casting refers to the casting process of aluminum liquid injected into the mould under the action o earth's gravity, and gravity casting is divided into: sand casting, metal mold casting, lost foam casting and so on. Now mostly used is Metal mould casting , the mould is made of heat-resisting alloy steel. The aluminum castings have better properties than other casting process in strength, size, appearance and so on.

The aluminum liquid is poured into the feeder manually.After filling, exhausting and cooling under the effect of metal self-weight, the castings are available. The process flow generally includes: aluminum liquid melting, pouring&filling, exhausting, cooling, mould opening, production cleaning,heat treatment and machining.

The characteristics of aluminum alloy gravity casting are:

Low smoothness, easy to create pits after shot blasting.

Less internal air holes, suitable to take heat treatment.

Low density and intensity, but high elongation.

Low mold cost and long service life.

Low production efficiency result in high production cost.

Simple technology, not suitable for thin wall products.

Thickness of the work piece is to be considered when choosing casting process. When it's more than 8mm, gravity casting is more suitable because die casting will cause a lot of air holes inside of walls. 

Presumably through this article, you must be aware of the differences and characteristics of aluminum alloy pressure casting and gravity casting. To learn more, please check out our website!