OEM customized pressure die casting aluminum/steel/stainless steel/brass parts services
Pressure casting refers to a casting method in which molten or semi-molten metal is injected into a metal mold at a high speed and crystallized under pressure, referred to as die casting. Common injection pressure is 30 ～ 70MPa, filling speed is about 0.5 ～ 50 m / s, and filling time is 0.01 ～ 0.2 s.
Pressure casting is a method of filling liquid or semi-solid metals or alloys, or liquid metals or alloys with a reinforcing phase into the cavity of a die-casting mold at a high speed under high pressure, and putting the metal or alloy under pressure A casting method that solidifies to form a casting. The pressure commonly used in die casting is 4 to 500 MPa, and the metal filling speed is 0.5 to 120 m / s. Therefore, high pressure and high speed are the fundamental differences between die casting and other casting methods. They are also important features. In 1838, Americans first produced printed typefaces by pressure casting, and the following year patents for pressure casting appeared. After the 1860s, the pressure casting method has been greatly developed. It can not only produce tin-lead alloy die-casting parts, zinc alloy die-casting parts, but also aluminum alloy, copper alloy and magnesium alloy die-casting parts. After the 1930s, tests of the steel pressure casting method were carried out.
The principle of pressure casting is mainly the principle of injection molding of molten metal. Generally, the casting conditions are set by adjusting the speed, pressure, and speed switching position on the die casting machine, and the others are selected in the die casting line.
Advantages of pressure casting
1) High productivity, easy to realize mechanization and automation, and can produce thin-walled castings with complex shapes. The minimum wall thickness of die-cast zinc alloy is only 0.3mm, the minimum wall thickness of die-cast aluminum alloy is about 0.5mm, and the minimum cast hole diameter is 0.7mm.
2) The casting has high dimensional accuracy and small surface roughness. Die castings have a dimensional tolerance level of CT3 ~ CT6, and the surface roughness is generally Ra0.8 ~ 3.2μm.
3) Casting parts can be embedded in the die-casting, which saves precious materials and machining man-hours, and also replaces the assembly process of components. The assembly process can be omitted and the manufacturing process can be simplified.
2. Disadvantages of pressure casting
1) The liquid metal is filled at a high speed during die casting, and it is difficult to completely eliminate the gas in the cavity. The casting is prone to defects such as pores and cracks and oxidized debris. Die castings usually cannot be heat treated.
2) The structure of the die casting mold is complex, the manufacturing cycle is long, and the cost is high, which is not suitable for the production of small batches of castings.
3) The die casting machine has high cost and large investment, and is limited by the clamping force of the die casting machine and the size of the die. It is not suitable for the production of large die castings.
4) Types of alloys are restricted, non-ferrous alloys such as zinc, magnesium, and copper.
Due to the advantages of die casting, it has been widely used, mainly for non-ferrous alloy castings produced in large quantities. In the production of die castings, aluminum alloy die castings accounted for the largest proportion, 30% to 50%; followed by zinc alloy die castings; copper alloy die castings accounted for 1% to 2%. The most widely used die castings are the automobile and tractor manufacturing industries, followed by the instrument manufacturing and electronic instrument industries, and again the agricultural machinery, national defense industry, computers, and medical equipment manufacturing industries. Parts produced by die casting include engine cylinder blocks, cylinder heads, transmission cases, engine covers, housings and brackets for instruments and cameras, pipe joints, gears, and so on.
In recent years, high technology has been used in the field of die casting. For example, a three-stage injection mechanism is used to control the pressure, injection speed and internal gas. Develop special die-casting processes (such as vacuum die-casting, directional air-pressure casting, oxygen-filled die-casting, etc.) and apply computer control technology to effectively remove pores and increase the density of castings. At the same time, develop new mold materials and new heat treatment processes to extend the life of the mold. Made some progress in ferrous metal die casting.