In-depth analysis of die casting process
Pressure casting, also known as die casting, is one of the core processes in the field of modern precision manufacturing. Its core principle is to instantly inject molten metal alloy into a precision steel mold cavity at an extremely high speed with the help of strong mechanical pressure. Unlike traditional casting that relies on gravity for molding, the Die Casting Process forces the molten metal to cool and solidify in a continuous high-pressure environment, ultimately forminghigh-precision castings. With significant advantages such as high molding efficiency, good product dimensional accuracy, and excellent surface finish, die casting has become the most widely used mainstream process with the fastest technology iteration in the field of metal thermal processing and forming.
From the perspective of output, the most commonly used die castings are magnesium alloy die castings, zinc alloy die castings and aluminum alloy die castings. Copper alloy die castings aren't commonly used.
In the field of modern precision die-casting, aluminum alloy, magnesium alloy and zinc alloy have become the three mainstream materials with their unique physical and chemical properties and are widely used in the manufacturing of precision parts in various industries.
Aluminum alloy, as the most widely used die-casting material, is known for its light weight and high strength. It isn’t only light in weight and has excellent mechanical properties, but also has good wear resistance, thermal conductivity and high temperature resistance. Therefore, it occupies a dominant position in automobile body structures, electromechanical equipment, consumer electronics casings and precision mechanical parts, and is the first choice for lightweight manufacturing. As an advanced non-ferrous alloy precision parts forming technology, aluminum die-casting adapts to the requirements of product complexity, precision, lightweight, energy saving and environmental protection in modern manufacturing industry and its application fields are constantly expanding.
Magnesium alloy is known as the "lightest engineering metal". Its density is much lower than that of aluminum, its specific strength is extremely high, and it has excellent shock absorption and impact resistance. In high-end fields that pursue extreme weight reduction, such as structural parts of new energy vehicles, ultra-thin casings of 3C electronic products, aerospace and handheld devices, magnesium alloy die-casting has become a key material for high-end manufacturing due to its lightweight advantages.
Zinc alloy is characterized by excellent casting performance, low melting point, stable molding and high dimensional accuracy. It is especially suitable for manufacturing small precision parts with complex shapes, thin walls and high surface finish requirements. It is widely used in hardware accessories, sanitary ware, electronic connectors, toys and various precision mechanical parts. It is the mainstream choice in the field of precision small castings.
Each of the three has its own strengths, and together they form the material cornerstone of the modern die-casting industry.
As the level of die-casting equipment and process technology continues to improve, the application scope of aluminum die-casting products will continue to expand on the existing basis. The main features that distinguish die casting from other casting methods are high pressure and high speed.
Cold and Hot Chamber Die Casting are the two basic methods of die casting process.
In cold chamber die casting, the molten metal is poured into the pressure chamber by manual or automatic pouring devices, and then the injection punch advances to hydraulically pump the metal into the mold cavity; in the hot chamber die casting process, the pressure chamber is perpendicular to the crucible, and the molten metal automatically flows into the pressure chamber through the feed port on the pressure chamber. The injection punch moves downward, pushing the molten metal into the mold cavity through the gooseneck. After the molten metal solidifies, the die-casting mold is opened and the casting is taken out to complete a die-casting cycle.
Hot chamber die-casting machine, also known as gooseneck die-casting machine, is the core equipment in the die-casting industry for efficient and precise molding of low-melting-point alloys. Its most notable feature is that the injection mechanism (gooseneck and punch) is directly immersed in the molten metal in the furnace, eliminating the need for manual or mechanical scooping of material for each cycle like the cold chamber die casting machine, thus achieving extremely high automation and production efficiency.
Integrated die-casting (giga-casting) refers to the technology of using ultra-large tonnage die-casting machines (clamping force ≥ 6,000 tons) to die-cast dozens to hundreds of parts that originally need to be stamped and welded into a single large component at one time after highly integrated design.
This technology eliminates the tedious process of separately producing and welding multiple parts. It not only significantly reduces the number of parts and assembly links, but also improves the strength, rigidity and reliability of the overall structure.
At present, integrated die-casting is mainly used in the lower body structure of new energy vehicles (rear floor, front cabin, battery casing, etc.).