The purpose of refining and slagging of aluminum alloy is to remove gas and impurities in liquid aluminum. In the existing die casting industry, the combination of physical adsorption and chemical reaction is often used.
When the die-casting aluminum alloy is melted, the way of rapid submergence is adopted, that is to keep a certain amount of aluminum water in the melting furnace, and do not use up. The crushed material is pressed into aluminum water for melting, so as to prevent direct burning of aluminum at high temperature for a long time to form oxidation. Aluminum ingot is added after the aluminum scrap is melted and the liquid level is increased. Do not stir when melting aluminum alloy to prevent oxidation and increase burning loss.
Refining and Slagging for Aluminum Alloy Liquid
Refining and slagging are the most important processes in the melting process of die casting aluminum alloy, and they are the control workers to avoid a large number of blowholes and hard spots.
Refining and slagging inside and outside the furnace can be adopted for crucible furnace and small and medium-sized pool melting furnace, because the treated liquid aluminum can be used up quickly. For large pool smelting furnace, it is better not to adopt in furnace refining and slagging treatment, but should be treated in special insulation bag or holding furnace, so as to reduce the amount of flux.
If the refined liquid aluminum is kept for a long time, it will be oxidized and inhaled continuously in contact with the atmosphere. If it is placed in the cast iron crucible for a long time, it will lead to iron increase and precipitate. It has been proved that the iron content in the cast iron crucible with poor protection or ineffective coating will increase when it is not used for more than 40 minutes. The liquid aluminum in the heat preservation cast iron crucible with shutdown time more than 40 minutes shall be transferred to the crucibles of other stations for use as soon as possible. If necessary, a small amount of refining agent can be used again after refining.
Some enterprises use large furnace to smelt aluminum, and then transfer package is distributed to each station in the holding furnace for use. In this case, if the molten aluminum is refined and slagging in a special holding furnace, the molten aluminum must be refined once, and the aluminum water should not be used at the same time, so the refining effect is not good. If it is directly transferred to the holding furnace of each station after smelting in the large furnace, the method of refining and slagging in the transfer package can be adopted, and the treated aluminum liquid can be poured into the holding furnace, or the slag can be refined in the holding furnace.