March 16 2021
For low to medium runs of parts that do not require precise shape repeatability aluminum sand casting is an excellent solution and is the only solution for very large objects.
The Process of Aluminum Sand Casting
For making aluminum expendable molds green sand is the most commonly used material. The process of aluminum sand casting can be summarized as follows:
By placing the mixture of sand, clay, and water on a pattern a mold is created. However, this process can be done by hand but the machinery is normally used to achieve better precision of the mold. After the removal of the pattern, the clay will have a cavity that corresponds to the shape of the pattern.
There are two or more parts of the sand mold, the upper part is known as the cope while the bottom one is called the drag. You can also use additional parts known as cheeks. In a two-part (or more if cheeks are used) box called a flask for protection, the molds are encased. Any sand cores needed to manufacture the part details are placed in the mold halves before the closure of the flask in sand casting of aluminum.
After the two halves are closed and clamped together the molten metal is then poured into the mold. Molten metal is fed in from the risers that were placed in the casting system after the metal starts to cool and some contraction takes place.
The cooling time is a lot longer than that of permanent mold or die casting as sand and clay do not absorb heat. To help provide an equal cooling rate throughout the cast chills can be inserted into the sand mold. As a consequence of the slower cooling, in the mechanical properties of alloys, there is an appreciable decrease.
The cast shake-out takes place after a preset dwell time to allow the metal to solidify. The metal cools down the molten metal heat while pouring into it dries out the moisture. This makes the cast easy to crack open in aluminum sand casting china. Follow us on Twitter