1）. Analysis of the Causes of Damage to High-Strength Castings on the Upper Parts of Aluminum Melting Furnaces.
1. Effect of Thermal Stress: During the operation of the aluminum melting furnace, the temperature inside the furnace can reach 700℃~900℃. In the process of frequent heating and cooling, thermal stress will occur due to the different expansion and contraction of each part of the upper casting. When the thermal stress exceeds the bearing capacity of the casting, cracking or delamination will occur. For example, when you heat the oven, the surface expands quickly due to heat, but the internal temperature rises slowly and the expansion decreases. This difference in internal and external expansion can easily lead to cracks.
2. Chemical corrosion: During the smelting process, aluminum liquid releases volatile substances such as alkali metal oxides, which will chemically react with the upper casting. When some castings interact with alkali metal oxides, low-melting point substances are generated, which reduces the high-temperature performance of the casting and accelerates wear.
3. Mechanical impact: When pouring materials into the aluminum melting furnace, there is a possibility that the impact of the materials will directly affect the upper casting. Especially when the materials are fed by air, they are unloaded at a high speed, so a certain impact force is exerted on the upper part of the furnace. In long-term use, the surface of the gypsum will gradually wear out and peel off.
4. Problems with the quality of the structure: If the mixing during the casting manufacturing process is uneven, the internal distribution of the casting will be uneven, and the performance will be unstable.
In addition, slight vibration will increase the porosity of the casting, reducing its strength and corrosion resistance, making it susceptible to damage during use.
2）. Maintenance Measures for High-Strength Castings on the Upper Parts of Aluminum Melting Furnaces
5. Optimize your thermal system. Set up logical heating and cooling curves to reduce the heating and cooling rates. For example, the heating rate is maintained at 50-80 °C per hour, and the cooling rate is maintained at 30-50 °C per hour to reduce the occurrence of thermal stress. At the same time, maintain a constant oven temperature and avoid large temperature fluctuations.
6. Select corrosion-resistant castings: Select castings with a high content of aluminum, corundum and other materials. This type of casting has excellent resistance to chemical corrosion. High-alumina castings have a high alumina content and effectively resist the corrosion of volatiles in aluminum liquid, thereby increasing the service life of furnace castings. 7. Improve the feeding method: Change the air supply direction to downward or horizontal feeding, so that the material does not enter the upper part of the furnace directly. At the same time, a shock-absorbing device such as a shock-absorbing baffle is installed at the top of the inlet to support the material before it enters the upper part of the furnace, thereby reducing the impact force on the upper casting inside the furnace.
8. Strict production quality control: Before construction, professional training is carried out to ensure that the construction personnel are familiar with the correct construction methods. In the production process, mixing is strictly according to the mixing proportion, and the mixing time is longer than the specified time to ensure uniform mixing. Whether the vibration is sufficient can be determined by using a corresponding vibration device to ensure that the vibration is tight and there is no air bubble on the surface of the casting.
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