Zinc alloy melting is an important part of the die-casting process. The melting process is not only to obtain molten metal, but more importantly, to obtain the chemical composition that meets the regulations, which can make the zinc alloy die-castings get a good crystal structure and the gas and inclusions are very small. Of molten metal. During the smelting process, the interaction between the metal and the gas and the interaction between the molten metal and the crucible cause changes in the composition, resulting in inclusions and inhalation. Therefore, the correct melting process is an important guarantee for obtaining high-quality castings.
1. The best melting temperature of Zinc die casting parts: the melting point of zinc alloy used for die-casting is 382 ~ 386℃, and proper temperature control is an important factor for zinc alloy composition control. In order to ensure the good fluidity of the alloy liquid to fill the cavity, the temperature of the molten metal in the zinc pot of the die-casting machine is 415 ~ 430℃. The temperature of the molten metal in the central smelting furnace is 430 ~ 450℃. The temperature of the molten metal entering the gooseneck is basically the same as the temperature in the zinc pot. The pouring temperature can be accurately controlled by controlling the temperature of the molten zinc in the zinc pot.
2. (When the melting temperature is too high)
The iron crucible reacts quickly with the zinc liquid, and iron oxidation reaction occurs on the surface of the crucible to produce Fe2O3 and other oxides. Iron elements will also react with the zinc liquid to form FeZn13 compound (zinc slag), which is dissolved in the zinc liquid. Aluminum and magnesium are burnt out, and metal oxidation speeds up, burning loss increases, and zinc dross increases. The effect of thermal expansion will cause the hammer head to jam. More iron is melted into the alloy in the cast iron crucible, and the reaction between zinc and iron is accelerated at high temperatures. Hard particles of iron-aluminum intermetallic compounds are formed, causing excessive wear on the hammer head and gooseneck. More iron is melted into the alloy in the cast iron crucible, and the reaction between zinc and iron is accelerated at high temperatures. Hard particles of iron-aluminum intermetallic compounds are formed, causing excessive wear on the hammer head and gooseneck. Fuel consumption increases accordingly. The higher the temperature, the coarser the crystals of the castings and the lower the mechanical properties.