Describe in detail the characteristics and differences of various castings

1. Casting can also be divided into gravity casting and pressure casting according to the pouring process of liquid metal. Gravity casting refers to the process of injecting liquid metal into the mold under the action of the earth's gravity, also known as casting. Generalized gravity casting including sand casting, metal casting, investment casting, clay casting; narrow meaning of gravity casting refers specifically to metal casting. Pressure casting refers to the process of injecting liquid metal into the mold under the action of other external forces (without gravity). Generalized pressure casting including die casting machine pressure casting and vacuum casting, low pressure casting, centrifugal casting, etc.; narrow sense of pressure casting refers specifically to the metal die casting machine pressure casting, referred to as die casting. Xudong Precision Casting Factory has long been engaged in gravity casting of sand molds and metal molds. These casting processes are the most commonly used in non-ferrous metal casting and the lowest relative price.

2. Sand casting is a traditional casting process that uses sand as the main molding material to make molds. Sand generally use gravity casting, there are special requirements can also be used low pressure casting, centrifugal casting and other processes. Sand casting has a wide range of adaptability, small pieces, large pieces, simple pieces, complex pieces, single pieces, large quantities can be used. The mold used for sand casting was previously made of wood, known as wood mold. In order to change the defects such as easy deformation and damage of wood molds, Xudong Precision Casting Factory has changed all of them to aluminum alloy molds or resin molds with high dimensional accuracy and long service life, except for sand castings produced by single pieces. Although the price has increased, it is still much cheaper than the mold used in metal casting, and the price advantage is particularly prominent in small batch and large production. In addition, sand mold is more refractory than metal mold, so materials with higher melting points such as copper alloys and ferrous metals are also used in this process. However, sand casting also has some shortcomings: because each sand mold can only be poured once, the mold is damaged after the casting is obtained and must be re-molded, so the production efficiency of sand casting is low; and because of the overall quality of sand Soft and porous, so the sand casting size accuracy is low, the surface is rough. However, Xudong Precision Casting Factory has greatly improved the surface condition of sand castings with years of technical accumulation, and its shot blasting effect is comparable to that of metal castings.

Metal mold casting is a modern process of making hollow mold for casting with heat-resistant alloy steel. The metal mold can be gravity casting or pressure casting. Metal mold mold can be used repeatedly, each pouring a liquid metal, get a casting, long life, high production efficiency. Metal castings are not only good dimensional accuracy, smooth surface, but also in the case of pouring the same metal liquid, the strength of the casting is higher than that of sand, and it is not easy to damage. Therefore, in the mass production of non-ferrous metals, small castings, as long as the melting point of the casting material is not high, generally preferred metal casting. However, metal mold casting also has some shortcomings: because the heat-resistant alloy steel and the processing of hollow cavities made on it are more expensive, the metal mold is expensive, but the overall cost is much cheaper than the die casting mold. For small batch production, the mold cost allocated to each product is obviously too high and is generally not acceptable. And because the metal mold is limited by the size of the mold material and the ability of the cavity processing equipment and casting equipment, it is powerless for particularly large castings. Therefore, in small batch and large production, metal mold casting is rarely used. In addition, although the metal mold uses heat-resistant alloy steel, but the heat resistance is still limited, generally used for aluminum alloy, zinc alloy, magnesium alloy casting, copper alloy casting has been less application, and used for ferrous metal casting is even less. Xudong Precision Casting Factory's metal molds are all self-designed and self-manufactured, so they can provide customers with cheap and suitable high-quality molds in a more timely manner.

4. Die casting is a metal mold pressure casting on a die casting machine, which is currently the highest production efficiency of the casting process. Die casting machine is divided into hot chamber die casting machine and cold chamber die casting machine two categories. The hot chamber die casting machine has a high degree of automation, less material loss, and higher production efficiency than the cold chamber die casting machine. However, due to the heat resistance of the machine parts, it can only be used for the production of castings of low melting point materials such as zinc alloy and magnesium alloy. The aluminum alloy die castings widely used today can only be produced on the cold chamber die casting machine due to their high melting point. The main feature of die casting is that molten metal fills the cavity under high pressure and high speed, and forms and solidifies under high pressure. The disadvantage of die casting is that during the process of filling the cavity under high pressure and high speed, the air in the cavity is inevitably wrapped inside the casting to form subcutaneous pores. Therefore, aluminum alloy die casting should not be heat treated, and zinc alloy die casting should not be sprayed with plastic (but can be painted). Otherwise, the internal pores of the casting will be thermally expanded when heated as described above, resulting in deformation or bubbling of the casting. In addition, the mechanical cutting allowance of die castings should also be smaller, generally about 0.5mm, which can reduce the weight of the casting, reduce the amount of cutting processing to reduce costs, and avoid penetrating the surface dense layer, exposing subcutaneous pores, resulting in workpiece scrap.