Low-pressure casting involves placing the mold in a sealed, insulated furnace, with the mold cavity connected to the molten metal in the furnace via a riser. During operation, pressurized air is introduced into the furnace, causing the molten metal to flow from the riser into the mold cavity. After the molten metal solidifies, the compressed air in the furnace is released, and any remaining liquid metal flows back into the furnace through the riser.

Many components are manufactured using low-pressure casting, such as the aluminum wheels and blades in torque converter cores. The resulting castings exhibit a dense microstructure and excellent mechanical properties. This process offers high yield rates—comparable to those of gravity casting—ranging from 70% to 80%, and boasts high production efficiency. For the same part, die casting achieves three times the productivity of gravity casting. Moreover, the surfaces are smooth and clean, reducing the need for extensive machining allowances.

Before commencing low-pressure casting, please inspect the mold first. After the production cycle is complete, if the coating has degraded or the surface is uneven, it must be polished with an abrasive wheel. Next, remove aluminum debris from the ejector pins and clean the vent plugs, then bake the mold at a working temperature of (360 ± 10)°C; therefore, the mold should be preheated to this operating temperature prior to use.

When the low-pressure die is heated to 300°C, a paint coating is applied; this coating must be uniform and free of runs. This prevents aluminum alloy from corroding the mold cavity, thereby extending the mold’s service life. It also inhibits adhesion of the aluminum alloy to the cavity or parting surface, enabling continuous, high‑speed production. Additionally, the coating forms an insulating layer on the cavity, protecting its microstructure, facilitating smooth flow of the molten metal into the cavity, reducing flow resistance, and enhancing the filling performance of the molten aluminum.

Next, the core is installed, and the low-pressure casting process parameters are set. The key process parameters for low-pressure casting include the molten aluminum temperature, the pressurization rate of the equipment, and the pressure setting. These three factors significantly influence the quality of the castings. Improper settings can lead to defects such as sand adhesion, insufficient filling, and blockages. Therefore, accurate parameter configuration is critical to the casting process.

Compared with conventional gravity casting, low-pressure casting can significantly increase casting output and deliver higher production efficiency. Because solidification occurs under pressure, the resulting castings exhibit a dense microstructure, with tensile strengths exceeding 200 MPa. However, low-pressure casting places more stringent demands on equipment, tooling, and process control, requiring meticulous attention during operation.

Low-pressure castings feature a dense microstructure, excellent gas tightness, stable dimensional accuracy, and reduced machining requirements, making them well suited for a wide range of sealed, pressure‑bearing components. We offer custom mold development based on your drawings or samples, and can tailor the casting process to meet specific operating conditions. Non‑standard, irregularly shaped parts and specially specified castings are all available on demand.