Design and Quality Requirements of Aluminum Alloy Die Castings

Introduction to Die Casting Process

Die casting (die casting for short) is a special casting method with little or no cutting, which has developed rapidly in modern metal forming process. The essence of the process is to make the liquid or semi liquid metal fill the die-casting cavity at a high speed under the action of high pressure, and form and solidify under pressure to obtain castings.

Characteristics of die casting process: High speed and high pressure are the main characteristics of die casting. The commonly used working pressure is tens of MPa, the filling speed is about 16~80m/s, and the filling time of molten metal in the mold cavity is very short, about 0.01~0.2s. Compared with other casting methods, die casting has the following three advantages:

1. Good product quality

The dimensional accuracy of castings is high, generally equivalent to Grade 6-7, or even Grade 4; Good surface finish, generally equivalent to Grade 5~8; The strength and hardness are relatively high. The strength is generally 25~30% higher than that of sand casting, but the elongation is about 70% lower; Stable size and good interchangeability; It can be used for die-casting thin-walled and complicated castings.

2. High production efficiency

The machine productivity is high. For example, the domestic J1113 horizontal cold air die-casting machine can die-casting 600~700 times per eight hours on average, and the small hot chamber die-casting machine can die-casting 3000~7000 times per eight hours on average; The service life of the die-casting mold is long. A pair of die-casting mold and die-casting bell alloy can reach hundreds of thousands of times, even millions of times; It is easy to realize mechanization and automation.

3. Good economic effect

Because the surface of die castings is smooth and clean. Generally, it is not used directly for machining, or the processing amount is very small, so it not only improves the utilization rate of metal, but also reduces a lot of processing equipment and man hours; The casting price is easy; Combination die casting can be used to make other metal or non-metallic materials. It saves both assembly time and metal.

Die casting is one of the metal forming methods. It is an effective way to achieve less chips and no chips. It is widely used and develops rapidly. At present, die-casting alloys are no longer limited to non-ferrous metals such as zinc, aluminum, magnesium and copper, but also gradually expanded to be used for die-casting cast iron and steel castings. The size and weight of die castings depend on the power of the die casting machine. Due to the increasing power of the die-casting machine, the shape and size of the castings can be from a few millimeters to 1~2m; The weight can range from a few grams to tens of kilograms. Aluminum castings with a diameter of 2m and a weight of 50kg can be diecasted abroad.

Die-casting alloy

The metal materials used to produce aluminum die castings are mostly aluminum alloy, pure aluminum, zinc alloy, copper alloy, magnesium alloy, lead alloy, tin alloy and other nonferrous metals, and ferrous metals are rarely used.