How to produce high quality gravity cast aluminum castings

Aluminum castings refer to metal products obtained by heating, melting, and casting pure aluminum or aluminum alloy ingots into the mold cavity in a crucible or medium frequency furnace. Generally, aluminum or aluminum alloy parts of various shapes and sizes are obtained by pouring heated liquid aluminum or aluminum alloy into the mold cavity using sand molds or metal molds.

The aluminum casting process is mainly divided into gravity casting, die casting, sand casting, and precision casting.

Gravity casting

Gravity casting of aluminum castings refers to the process of injecting aluminum liquid into a mold under the influence of Earth's gravity.

Generally, metal molds (steel molds) are used for casting, and their molds are made of heat-resistant alloy steel. The aluminum castings cast have higher strength, size, appearance, etc. than other casting processes.

Aluminum liquid for gravity casting is generally automatically cast using a gravity casting machine, relying on the self weight of the metal liquid to fill the mold cavity, exhaust, cool, and open the mold to obtain the sample. The process flow is generally as follows: aluminum liquid melting, pouring and filling, exhaust, cooling, mold opening, clearing, heat treatment, and processing.

The characteristics of aluminum alloy gravity castings are:

1. The product has a high surface finish and high density.

2. Aluminum castings have fewer internal pores and can be subjected to heat treatment.

3. High elongation rate.

4. The cost of molds is high, and the service life of molds is long.

5. High production efficiency reduces production costs.

6. The process is relatively simple and has strong adaptability.

When choosing which production process to use for a product, the selection is mainly based on the wall thickness of the workpiece. When the wall thickness of the product is greater than 8mm, die-casting will cause many air holes to exist in the wall. Therefore, products with thicker wall thickness can be completed by gravity casting process.