Casting is an extremely simple and inexpensive method of forming aluminum into different kinds of products. The process of casting mainly involves pouring of liquid aluminum into a mold. These castings are used to make complex parts which have extra details to them, very efficiently. The mold has to be made with precision since it is directly responsible for the shape and surface finish of the final cast produced.
The mold can be made from different materials such as tool steel, since the melting point of aluminum is lower than steel.
Methods of Aluminum Casting
The three most common and important method for aluminum casting-
1. DIE CASTING
The die casting process forces the liquid aluminum into a steel die or mold under pressure. The mold cavity is made by using two hardened tool steel dies which have been given the desired shape. Most of the die castings are made up of non-iron metals such as zinc, copper, magnesium, aluminum etc.
There are generally four steps in a typical die casting technique are used by alloy steel casting manufacturers industry .
- Die preparationThe dies are prepared where the mold cavities are sprayed by the water-based lubricant. The lubricant essentially helps to control the temperature and removal of the casting from the mold.
- FillingThe dies are filled by injecting molten metal at a pressure of 10 to 175 mega Pascal.
- EjectionThe pressure is maintained steadily until the cast solidifies completely. These dies are then opened and shots are ejected by the use of ejector spins.
- ShakeOutIt involves the separation of the scrap and is often done by using the special trim die in hydraulic pressure. This method is being very much nowadays by alloy casting manufacturers.
2. SAND CASTING
Sand casting is a process of metal casting which is characterized by the use of sand as the mold materials. The sand casting technique is relatively cheaper. Along with the sand, a bonding agent such as clay is mixed with the sand. This mixture of sand and clay is mixed with water or other substance to make the aggregate suitable to mold.
The sand is typically contained in a system of frames created by keeping the sand compact around the molds.
There are six basic steps involved in the process-- A pattern has to be placed in the sand to create a mold.
- In a gating system, the pattern along with the sand has to be incorporated.
- Remove the pattern.
- The mold cavity has to be filled with the liquid metal.
- Keep the mold until the metal cools down.
- Break the sand mold to remove the casting.
3. PERMANENT MOLD CASTING
This process involves molds of steel and other metals. The molten aluminum is poured into the mold along with the application of vacuum. These permanent mold castings are made stronger than both the die casting and sand casting.Semi-solid permanent mold casting methods are used in conditions where the permanent cores are impossible to remove from the finished product.
The alloy steel casting manufacturers employ this method to create permanent products of desired shape and size.