The traditional die casting process is mainly composed of four steps, or high pressure die casting. These four steps include mold preparation, filling, injection, and sanding, which are also the basis of various improved die-casting processes. In the preparation process, it is necessary to spray lubricant into the mold cavity. Lubricant can not only help control the temperature of the mold but also help to demould the casting. The mold can then be closed and the molten metal can be injected into the mold with high pressure, which ranges from about 10 to 175 MPa. When the molten metal is filled, the pressure will be maintained until the casting solidifies.
Then the pushrod will push out all the castings. Since there may be multiple cavities in a mold, multiple castings may be produced in each casting process. The process of sand falling requires the separation of residues, including mold-making gate, runner, gate, and flash. This process is usually accomplished by extruding the casting with a special dressing die. Other sanding methods include sawing and grinding. If the gate is fragile, you can directly beat the casting, which can save manpower. The excess die can be reused after melting. The usual yield is about 67%. Now, we in-depth the development history and industry potential of the copper die casting process.
Copper die casting is a high-temperature die-casting method in which liquid copper or copper alloy is filled into the cavity of the die-casting mold at a high speed under high pressure, and the copper or copper alloy solidifies under pressure to form a casting. Advantages: the casting has high precision, can produce parts with complex structure, high production efficiency and is suitable for mass production.
Disadvantages: due to high temperature (900-1100 degrees) and high density, there are high requirements for equipment, mold, material melting and other processes.
In 1838, die casting equipment was invented in order to make molds for movable type printing. A patent related to die casting was issued in 1849. It is a small manual machine used to produce a type of printing press. In 1885, Otto Morgenthaler invented the Linotype typesetting machine, which can die cast a whole line of text into a single type, which brought unprecedented innovation to the printing industry. After the large-scale industrialization of the printing industry, the traditional hand pressed font has been replaced by die casting.
Around 1900, typesetting entered the market, which further improved the automation technology of the printing industry. Therefore, sometimes more than ten die-casting machines can be seen in the newspaper. With the continuous growth of consumer products, Otto’s invention has gained more and more applications. People can use die casting to manufacture parts and components in large quantities. In 1966, general dynamics invented the fine speed and dense die casting process. In recent ten years, with the progress and improvement of die-casting equipment, die materials, technology and market demand, die-casting of high-temperature materials such as copper and copper alloy has gradually appeared and developed.
The economy has maintained a momentum of rapid development. Due to the intensification of the contradiction between resources and environment, according to the requirements of the scientific outlook on development, circular economy and cleaner production have become important national policies for the sustainable development of social economy. Experts pointed out that the category of die casting, including various non-ferrous metal casting and molding processes under pressure such as low-pressure casting and squeeze casting, has a total output of about 3 million tons. Copper alloys have high mechanical properties, and their values are higher than those of zinc, aluminum and magnesium alloys.
Copper alloy has good conductivity and diamagnetic property. It is often used to make parts on instruments that are not allowed to be disturbed by magnetic field. Copper alloy has small coefficient of friction, small coefficient of linear expansion, and high wear resistance, fatigue limit and thermal conductivity. Copper alloy has high density and high melting point. It is widely used in automobiles, motorcycles, transportation, electrical instruments, communications and telecommunications, medical and health care, mechanical equipment, monitoring, sports equipment, handicrafts, toys, furniture, bathroom lighting, clothing, shoes and hats, daily necessities and other industries.