Low pressure casting is the casting plant will be placed in a closed holding furnace, the cavity is connected with the molten metal in the furnace through the riser. During operation, the foundry feeds pressurized air into the furnace and the molten metal flows into the cavity from the riser. After the molten metal solidifies, the compressed air in the furnace is released, and the unsolidified metal flows back into the furnace from the riser.

Many parts are manufactured using low-pressure casting technology, such as aluminum wheels and blades in the core of the torque converter. The resulting castings are dense and have good mechanical properties; the low-pressure casting process has a high yield of finished products, which is the same as gravity casting, and the yield can reach70% to 80%. The production efficiency is high, and the production efficiency of the die-casting process of the same product is three times that of gravity casting. And smooth surface, can reduce the machining allowance.

When the foundry starts low-pressure casting, it is necessary to check the mold first. After the end of the production cycle, when the paint fails or the surface is uneven, it needs to be polished with a grinding wheel. Then clean the ejector rod aluminum shavings and exhaust plug, and then bake the mold, the working temperature is (360±10)℃, so the foundry should bake the mold to working temperature before work.

Low die casting mold heatedSpray paint at 300 ℃, and the paint surface should be uniform and free of sagging. This can prevent aluminum alloy corrosion cavity, prolong the life of the mold; can also prevent aluminum alloy adhesion in the cavity or parting surface, which can be continuous and rapid production; can also make the cavity has a layer of heat insulation, protection organization, so that the molten metal is easy to flow into the cavity, reduce the flow resistance of aluminum liquid, improve the filling performance of molten metal.

Then the foundry needs to set the core and set the low pressure casting process parameters. The process parameters of low pressure casting are mainly aluminum liquid temperature, equipment pressure speed and pressure setting. These three factors will affect the quality of the casting. If the setting is not good, it will cause defects such as sand sticking, insufficient pouring, and blockage. Therefore, parameter setting is very important for casting.

Compared with traditional gravity casting, low-pressure casting can greatly increase the output of castings and work more efficiently. Due to pressure crystallization, the casting structure is dense and the tensile strength can reachMore than 200MPa. However, low-pressure casting has higher requirements for equipment, molds and processes, and foundries need to pay more attention to casting.