Since the moisture and rust products on the metal surface are the primary reasons for the contamination of the alloy due to oxidation, in order to obtain a purer aluminum alloy, the aluminum ingot must be dry and free of dirt. The molten aluminum from the smelting furnace needs to be degassed and slag removed before being transferred to the machine for production. Generally, the floating method is used for nitrogen refining, and the refining agent is added for molten aluminum rotating degassing, and the alumina inclusions in the aluminum liquid are adsorbed by nitrogen bubbles and brought to the surface of the aluminum liquid for manual removal.
The pore defects of aluminum alloy die castings are caused by the gas being absorbed by the cast aluminum alloy during melting, so preventive measures can be solved from the melting process:
1) The charge should be placed in a dry place to avoid exposure to moisture due to sunlight and rain, so as to avoid the increase of hydrogen content during melting;
2) Tools in contact with molten aluminum must be painted and preheated;
3) During smelting, the temperature of the molten aluminum should be strictly controlled, and the limit should not exceed 750℃. The higher the temperature of the molten aluminum, the more hydrogen intake. The longer the residence time of the degassed and refined molten aluminum in the transfer bag, the faster the gas content increases;
4) The deaerator should be sufficiently dry.
In summary, under the premise of good smelting process management and control, high-quality die castings with less porosity can be obtained. AdTech offers aluminum casting flux, online degassing unit for molten aluminum rotating degassing. Online degassing unit adopts advanced high silicon melting technology to get a long service time, degassing rotor, heater protection thimble and thermocouple protection thimble adopt ceramic manufacturing technology which can meet producing high-precision aluminum requirements. Online degassing unit shall be installed between furnace and casting equipment. It is used for hydrogen (H) and slags removal from molten aluminum. The online degassing unit has dual functions: processing and heating. It serves high precision molten aluminum purification industry.