What is aluminum alloy gravity casting?

Aluminum alloy is widely used in automobile manufacturing, aerospace, shipbuilding and other fields because of its good plasticity, corrosion resistance, lightweight and other characteristics. With the development of Chinese manufacturing industry, the demand for aluminum alloy and aluminum alloy castings is increasing, which will also promote the development of aluminum alloy casting industry. At present, the casting methods of aluminum alloy are divided into pressure casting and gravity casting. Taiying metal will analyze the differences and characteristics of the two casting processes in detail.

Aluminum alloy casting process can be roughly divided into two kinds: gravity casting and pressure casting.

Aluminum alloy pressure casting refers to the process of injecting molten metal into the mold under the action of other external forces (excluding gravity). Pressure casting is divided into high-pressure casting and low-pressure casting.

High pressure casting is what we usually call die casting, which pours the aluminum liquid into the pressure chamber, fills the mold cavity through its pressure at high speed, and solidifies the aluminum liquid under pressure to form an aluminum casting.

The characteristics of aluminum alloy die castings are:

1. The surface finish of the product is good, generally up to ra6.3 or even Ra1.6.

2. Do not heat treat.

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

4. The mold cost is high and the service life is short.

5. High production efficiency.

6. It can produce thin-walled parts with small machining allowance.

Gravity casting of aluminum alloy refers to the process of injecting molten aluminum into the mold under the action of gravity of the earth. Gravity casting is divided into sand mold casting, metal mold (steel mold) casting, lost foam casting, etc.

Now the most widely used is metal mold (steel mold) casting, which is made of heat-resistant alloy steel. The strength, size and appearance of the cast aluminum castings are higher than those of other casting processes.

The aluminum liquid of gravity casting is generally poured into the gate by hand, and the mold cavity is filled, vented, cooled, and opened to obtain samples by relying on the self weight of the metal liquid. The process flow is generally as follows: aluminum liquid smelting, casting material filling, venting, cooling, mold opening, liquidation, heat treatment, and processing.

The characteristics of aluminum alloy gravity castings are:

1. The surface finish of the product is not high, and it is easy to produce pits after shot blasting.

2. Aluminum castings have few internal pores and can be heat treated.

3. The product has low compactness, slightly poor strength, but high elongation.

4. The cost of the mold is low and the service life of the mold is long.

5. The production efficiency is low, which increases the production cost.

6. The process is relatively simple, which is not suitable for the production of thin-walled parts.

When choosing the production process of products, it is mainly based on the wall thickness of the workpiece. When the wall thickness of products is greater than 8mm, die casting will cause many pores to exist in the wall, so the products with thick wall thickness can be completed by gravity casting process.