Effect recycled aluminium structures of metallurgycal and melt efficiency

Generally, an expired structure aluminum is recycled into raw materials for the next casting process or component products. Slag and aluminum left in the ladle caused low melting efficiency. Microstructure formed in the castings components solidification process is often used to control mechanical properties and the castings fabrication. The purpose of this study is to improve structure aluminum recycling process quality. This recycling study used structure aluminum raw materials with recycling levels variations in the 1st, 2nd, 3rd, and 4th. In the first recycling, the structure aluminum pieces as melting raw materials weighing 2 kg were put in the induction furnace for melting. Let the aluminum pieces melted in the furnace and the temperature continued to rise to 700°C. Next, separated and took the floating slag on top of liquid aluminum, lifted the ladle from the furnace and poured the aluminum in the ingot mold from the permanent mold. After the ingots in the mold were being frozen and cooled, removed the ingots from the mold to be weighed and tested for microstructure. In the second recycling, the melted raw material was the first recycling ingot with the same procedure. In the third recycle, the melted raw material was the second recycling ingot with the same procedure; and the third recycling, the raw material that was melted was the third recycling ingot with the same procedure. Then the slag and ingot was weighed, and microstructure photos from the ingots were taken. From the microstructural photographs results, a calculation process can be performed to determine the grain size of each specimen. For smelting efficiency testing results at each recycling stages respectively 1st, 2nd, 3rd, and 4th were 76.23%, 82.64%, 85.17%, and 89.55%. The largest microstructure diameter at the first recycling for the surface part was 42,512 µm and the center was 43,314 µm. The smallest grain diameter of the 3rd recycling for the surface part was 42,164 µm and the center was 42,346 µm. (paper)