Under high pressure, pour semi-liquid or liquid metal into the die cavity. And metal solidifies quickly under pressure to obtain the final product. This method of making metal parts is die casting. The average pressure for casting manufacturing process is from several MPa to dozens of MPa. And the initial filling speed is in the range of (0.5～70) m/s. Therefore, high pressure and high speed are essential features of die casting methods.
Die casting machine, material and casting mold are the three major elements in die cast parts manufacturing process. All of them are indispensable. Using these three elements organically, it enables the stable, rhythmic and efficient production of qualified or even high quality die castings. They have good appearance, internal quality, and dimensional accuracy. Of course, meet the drawing or agreement requirements.
Die castings material
The die casting alloys that the final product always uses are nonferrous metals. Due to problems such as mold material, we rarely adopt ferrous metals, such as steel and iron. And among them, aluminum alloys are widely used, followed by zinc alloys. In the electronic industry, cast metals we mainly use include zinc, aluminum, and magnesium alloys. In general, the casting temperature is measured by that of the molten liquid metal in the holding furnace. And that of zinc alloys should not exceed 450℃ high temperatures to avoid coarse grains.
Die casting machine
For the pressing chamber’s heating conditions, the machine for casting methods can be divided into two categories. They are hot chamber machines and cold chamber machine. Also, the press chamber and the placement position of casting molds are different. So the cold chamber machine had three types: vertical, horizontal and full vertical die casting machine. They are suitable for casting high melting point metals, such as copper alloy. While, we use hot chamber die casting for low melting point alloys, like zinc and tin.
Die casting mold
Die casting molds are metal dies used to form cast part in the die casting process. The critical role of them in the production process include these.
First of all, determine the shape and dimensional accuracy of die cast parts. Secondly, the gating system (especially the gate position) determines the filling condition of the molten metal. Thirdly, the predetermined overflow system affects the filling conditions of molten liquid metal. Fourthly, the strength of the casting mold limits the maximum injection pressure. Then,it affects the efficiency of the casting cycle operation. Also, control and adjust the heat balance of the die casting process. Besides, it depends the quality of the cast part when taken out. The quality of die halves forming surface not only affects the quality. Also, it affects the casting cycle, and the difficulty of taking out die castings.
As we all know, the shape and dimensional accuracy of castings, surface requirements and internal quality, and the smoothness of production operations is vital. And they often directly relate to the die casting mold design and manufacturing quality. More importantly, after making the steel mold, the degree of modification is not great. And the relationship between the functions mentioned above and the quality of die cast parts is relatively fixed. This is why we make the steel mold design and production on the basis of die casting process requirements.
Die casting mold design principles
Carry out a comprehensive and full understanding
(1) Fully know the use of die castings and their assembly relationship with other structural parts. According to these of metal parts, we need to distinguish the primary and secondary during the mold design. And highlight the mold structure’s key points. Besides, combined with the molding processes, reasonably selecting these. For example, parting line and surface, number of multiple cavities and layout form, push-out form and lateral demolding form of the cast part. (2) To understand the actual processing capacity of the metal dies on site. Such as the existing equipment and that of cooperating units, and the technical level of the operators. According to the actual situation, design the mold structure that meets the on-site processing ability. (3) Casting molds should adapt to the various technological requirements of die casting production. Select the gating system and overflow system that meet the die casting process requirements. Especially, foucus on the position, speed, and liquid flow direction of the inner gate. After the molten metal is injected into the dies, it should flow smoothly. And the gas in the multiple cavity should be discharged in an orderly manner. So it can achieve a good filling effect and avoid die casting defects.