Brass Casting Process

Brass is a copperzinc alloy with excellent mechanical properties, corrosion resistance and electrical conductivity. Compared with pure copper, brass has higher hardness and lower cost, making it more popular in industry. Compared with aluminum alloy castings, brass castings exhibit superior strength and wear resistance but are heavier. In comparison with stainless steel castings, brass features lower cost and better machinability, yet its high-temperature resistance and corrosion resistance are slightly inferior. These characteristics determine the advantages of brass castings in specific applications.

The first high-quality step in producing brass castings is raw material preparation. High-purity electrolytic copper and zinc ingots are selected as the main raw materials, with strict control over impurity content. Unlike other factories that use recycled copper, this company adopts virgin materials to ensure stable chemical composition and mechanical properties of the castings. After weighing and proportioning, the raw materials are fed into a melting furnace for melting.

Melting is a critical stage in brass casting production. Medium-frequency induction electric furnaces are adopted for melting. This equipment ensures uniform heating and precise temperature control, effectively reducing metal oxidation and gas absorption. Compared with traditional coal-fired or gas-fired furnaces, electric furnaces feature lower energy consumption and less environmental pollution, meeting the requirements of modern green manufacturing. During melting, workers add appropriate amounts of deoxidizers and refiners to remove impurities and bubbles from the molten metal.

After melting, the molten metal is transferred to a holding furnace for temporary storage prior to pouring. Pouring refers to the process of injecting molten metal into molds. Two methods are used: gravity pouring and low-pressure pouring. Gravity pouring is suitable for simple-structured castings with low cost. Low-pressure pouring is applied to complex-structured castings, which can reduce defects such as blowholes and shrinkage porosity. Compared with high-pressure die casting, low-pressure pouring requires less equipment investment but has slightly lower production efficiency. The company flexibly chooses the pouring method according to product requirements.

Molds are a key factor determining the shape and surface quality of castings. The company employs two processes: sand casting and permanent mold casting. Sand casting is suitable for small-batch, multi-variety production; molding materials are reusable and cost-effective. Permanent mold casting is designed for mass production, delivering high dimensional accuracy and good surface finish of castings. Compared with lost foam casting, sand casting is more mature and widely applicable, though the surface quality of castings is slightly lower.

Castings after pouring undergo cooling and mold release. Cooling time is adjusted based on the size and wall thickness of castings, as either overly fast or slow cooling will impair product quality. After demolding, castings enter the cleaning stage, including removal of gates, risers, fins and burrs.