About Aluminum :
Aluminum is among one of the few metal which can be casted by all the processes used in casting metals. Also considered as the third most abundant metal in the Earth's crust, this metal is a silvery white, ductile metal usually not soluble in water under normal circumstances.
Throughout the late 19th century, aluminum casting alloys have played an essential role in the growth of the global aluminum industry. The first commercial products which are fabricated out of aluminum that showed the utility and novelty of this metal are decorative items and cooking utensils. After the development of these items, the applications of this metal has expanded to other arenas very fastly to meet the ever growing requirements and demands of a vast range of engineering applications. Over last 10 years, many enhancements in alloys and appropriate characterization of mechanical and physical properties of aluminum developed the basis for new product advancement with the use of new technologies.


Applications :
New casting processes are introduced in order to expand and enhance the adequacies of foundries in more commercial and technical applications. Thorough research and various technologies like solidification, molten metal processing technology, new property development have provided the foundry man with the tools of cost effective and reliable construction technologies, which can fulfill specified requirements of the industry. In recent times, aluminum alloys have been casted in innumerable compositions including :

• Composite mold
• Plaster mold
• Green sand
• Dry sand
• Investment casting permanent mold
• Pressure die casting
• Counter gravity low pressure casting

Factors :
The selection criteria for manufacturing a specific aluminum alloy part is based on various factors. The most important are :

• Feasibility: Although several aluminum alloy castings can be manufactured by any of the method, still in certain cases design features or dimensions of components automatically ascertain the most appropriate casting process.
• Quality factor: The word quality refers to degree of soundness which means freedom from porosity, cracking and surface imperfections and mechanical properties that stands for mainly strength and ductility.
• Cost factor

Usually, bigger casting parts are made through sand casting as metal molds normally weigh from 10 to 100 times as much as the components they manufacture. Where as, small casting parts are fabricated using metal molds that assure dimensional accuracy of the casting they produce. In die casting process, large and high cooling rates results in air to be trapped in the casting. This procedure produces high amount of porosity at center of casted products. Though, R&D has been done to find a way for lowering the porosity but this is also the true fact that it is impossible to eradicate entire porosity. Thus, die casting products are lower in strength as compared to low-pressure or gravity-fed permanent mold castings that have slower cooling rates, but produce strong components.