Aluminum alloys are divided into two categories: cast aluminum alloys, which are used in the as cast state; Deformed aluminum alloy, able to withstand pressure,. It can be processed into aluminum alloy materials of various shapes and specifications. It is mainly used for manufacturing aviation equipment, doors and windows for construction, etc.

Aluminum alloy can be divided into deformation aluminum alloy and casting aluminum alloy according to the processing method. Wrought aluminum alloys are also divided into non heat treatable strengthened aluminum alloys and heat treatable strengthened aluminum alloys. Non heat treatable reinforced type can not improve mechanical properties through heat treatment, but can only be strengthened through cold working deformation. It mainly includes high-purity aluminum, industrial high-purity aluminum, industrial pure aluminum and rust proof aluminum. Heat treatable strengthened aluminum alloy can improve its mechanical properties by quenching, aging and other heat treatment methods. It can be divided into hard aluminum, forged aluminum, superhard aluminum and special aluminum alloys.

Some aluminum alloys can be heat treated to obtain good mechanical properties, physical properties and corrosion resistance.

Cast aluminum alloys can be divided into aluminum silicon alloys, aluminum copper alloys, aluminum magnesium alloys, aluminum zinc alloys and aluminum rare earth alloys according to their chemical composition. Among them, aluminum silicon alloys include simple aluminum silicon alloys (which cannot be strengthened by heat treatment, have low mechanical properties and good casting properties), and special aluminum silicon alloys (which can be strengthened by heat treatment, have high mechanical properties and good casting properties)

Aluminum suitable for die-casting process is die-casting aluminum, usually die-casting aluminum alloy. It has a set of core pulling and cooling systems with high technical content. In general, materials are sent to the mold cavity to be cast through a centralized inlet to form parts.

Casting is a process of metal smelting and processing, which usually uses the gravity of metal to cast in the mold. But "aluminum die casting" is not completed by gravity, but by exerting a certain amount of pressure. It is similar to "injection molding". But it has a set of core pulling and cooling systems with high technical content. In general, materials are sent to the mold cavity to be cast through a centralized inlet to form parts.

Process characteristics

High pressure and high-speed filling die-casting aluminum mold are two major characteristics of die-casting aluminum. Its commonly used injection specific pressure is from thousands to tens of thousands of kPa, even as high as 2 × 105kPa。 The filling speed is about 10~50m/s, and sometimes it can even reach more than 100m / s. The filling time is very short, generally within the range of 0.01~0.2s.

advantage

1. Good product quality: high dimensional accuracy of castings, generally equivalent to grade 6-7, or even grade 4; Good surface finish, generally equivalent to grade 5~8; The strength and hardness are higher, and the strength is generally 25~30% higher than that of sand casting, but the elongation is reduced by about 70%; Stable size and good interchangeability; Die casting aluminum thin-walled complex castings. For example, at present, the minimum wall thickness of zinc alloy die-casting aluminum parts can reach 0.3mm; Aluminum alloy castings can reach 0.5mm; The minimum cast hole diameter is 0.7mm; The minimum pitch is 0.75mm.

2. High production efficiency: the machine has high productivity. For example, the domestic J Ⅲ 3 horizontal cold air die casting aluminum machine can die cast aluminum 600 ~ 700 times in eight hours on average, and the small hot chamber die casting aluminum machine can die cast aluminum 3000 ~ 7000 times every eight hours on average; The service life of die-casting aluminum mold is long. A pair of die-casting aluminum mold and die-casting aluminum clock alloy can have a service life of hundreds of thousands or even millions of times; It is easy to realize mechanization and automation.

3. Excellent economic effect: due to the precise size of die-casting aluminum parts, the surface is bright and clean. Generally, it is no longer used directly for machining, or the processing volume is very small, so it not only improves the utilization rate of metal, but also reduces a lot of processing equipment and working hours; Castings are cheap; Composite die cast aluminum can be used with other metallic or non-metallic materials. It saves both assembly time and metal.

shortcoming

1. When die casting aluminum, due to the high speed of filling the mold cavity with liquid metal and the unstable flow state, the general die casting aluminum method is adopted, and the castings are easy to produce pores and cannot be heat treated;

2. For castings with complex concave, it is difficult to die cast aluminum;

3. High melting point alloys (such as copper, ferrous metals), die-casting aluminum mold life is low;

4. It is not suitable for small batch production. The main reason is that the manufacturing cost of die-casting aluminum mold is high, the production efficiency of die-casting aluminum machine is high, and small batch production is uneconomical.

Source: Changjiang nonferrous metals network

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