Low-pressure casting refers to placing the mold above the sealed crucible, and then introducing compressed air into the crucible to generate low pressure on the surface of the molten metal, so that the molten metal rises from the crucible, the riser tube fills the mold and controls the solidification casting method.

Low-pressure casting This casting method has good feeding and compact structure, easy to cast large thin-walled composite castings, no risers, and high metal recovery rate95%. No pollution, easy to realize automation. However, the equipment cost is high and the production efficiency is low, and it is usually used for casting non-ferrous alloys.

Low pressure casting is a casting method in which a liquid alloy is pressed into a cavity from bottom to top under pressure and solidified under pressure to obtain a casting. The sealed crucible is filled with dry compressed air or inert gas, and the molten metal flows downward to the standpipe by means of pressure acting on the surface of the molten metal. The mold is steadily filled into the upper through the flow channel, and the filling pressure is usually20-60kPa. After the casting is completely solidified, the air pressure on the liquid surface is released, so that the unsolidified molten metal in the riser and runner flows into the crucible by its own weight, and then the mold is opened for casting and then taken out.

The production process of low pressure casting includes the following four basic processes:

1,Metal smelting and mold manufacturing.

2、Preparation work before pouring: including crucible sealing (installation of sealing cover), slag removal in the riser, liquid level measurement, sealing test, mold matching, tightening mold or mold, etc.

3,Pouring: including liquid lifting, filling, pressurizing, curing, pressure relief and cooling, etc.

4,Demoulding: including loose molding and casting.

Low pressure casting is an earlier anti-gravity casting technology, inUsed in industrial production in the 1940 s. Nowadays, low-pressure castings are mainly used to produce aluminum alloy and magnesium alloy parts, such as automobile wheels, cylinder blocks, cylinder heads, pistons, impellers, wind guides and other castings with complex shapes in the automotive industry. The automotive industry has relatively high quality requirements. When using low-pressure casting to produce cast steel (such as cast steel wheels), the riser must be made of special refractory materials. Low pressure casting can also be used for small copper alloy castings, such as pipe fittings, cock faucets in bathrooms, etc.