Aluminum alloy melting process
1. The composition of the aluminum alloy ingot meets the standard and is dry to prevent the moisture adsorbed on the surface of the alloy material or the melting tool from being dissolved into the molten aluminum and converted into hydrogen. When the new material is matched with the returned material, the returned material shall not exceed 50%. Return material refers to the gate overflow groove and scrap castings. The flash and debris must be re-melted and cast into ingots before use, otherwise direct use will bring a large amount of oxides. The moisture and impurities on the returned charge will increase the gas content of the melt, so it must be cleaned and dried before being put into the smelting furnace. Reasonable control of feeding amount, feeding time and block size.
2. Melting temperature: controlled within the range of 670~760℃. If the temperature is too high, oxidation or inhalation will occur, and if the temperature is too low, it is difficult to separate the slag.
3. The role of flux:
Covering agent: It can form a liquid protective layer during the smelting process so that the metal does not oxidize or absorb hydrogen.
Slag-forming agent: absorb oxides and non-metallic substances to collect on the metal liquid surface to remove.
Purifying agent: use the floating process to remove non-metallic impurities in the molten metal.
Modifier: Sodium is added to improve microstructure.
Use flux for refining, degassing and slag removal. The aluminum alloy flux injection comprehensive treatment device can be used to complete the metamorphism and grain refinement in one step. High-efficiency refining methods such as nitrogen blowing by rotating rotor method and flux injection method can also be used to refine molten aluminum.
4. Keep the liquid level in balance during the smelting process. Reasonably control the discharge temperature and time, and reduce the holding time.
5) In order to obtain a purer alloy liquid, the aluminum alloy liquid from the melting furnace can be filtered through a ceramic filter to filter out the inclusions, and then sent to the holding furnace of the die-casting machine.