Pouring Molten Aluminum is an important step for obtaining qualified castings. In order to prevent and reduce casting defects, the following matters need to be paid attention to when pouring.
Before pouring molten aluminum, carefully check the temperature of the molten aluminum, the capacity of the ladle, and the dryness of the surface coating layer, and whether the preparation of other tools meets the requirements.
Before pouring aluminum melt, check the temperature of the mold and the spraying condition of the paint carefully. BN Coating is the key factor of metal mold casting. The metal mold has fast cooling speed, no retreat, and no air permeability, which is basically improved by coating. The coating has a low thermal conductivity and slow cooling speed, which improves the cooling speed of the metal mold and prevents the castings from producing cold barriers and insufficient pouring defects. The talc powder in the coating has the effect of demoulding, which improves the influence of the non-recession of the metal mold, that is, to ensure the mold taking, prevent the casting from strain, crack, and deformation defects, and protect the mold. The coating has a certain degree of venting, which improves the problem of non-venting of metal type and prevents pores and pinhole defects. Therefore, we must pay attention to the role of BN coatings.
It should not be poured under windy conditions to avoid strong oxidation and combustion of molten aluminum, which may cause defects such as oxidation inclusions in the castings. In particular, the fan cannot be blown against the smelting furnace and holding furnace, let alone the ladle when pouring.
When scooping aluminum water from the crucible, first use the bottom of the bag to gently poke off the oxide scale or flux layer on the surface of the aluminum water, slowly immerse the ladle into the melt, and use the wide mouth of the ladle to scoop the aluminum water, and then Lift the ladle smoothly.
When handling the ladle, the palm must be flat, the pace must be steady, and the ladle should not be raised too high. The aluminum water level in the ladle must be kept stable and not disturbed.
When pouring is about to be carried out, the slag of the ladle should be cleaned to prevent molten slag and oxide scale from being carried into the casting during pouring molten aluminum.