Several matters needing attention in the process of aluminum die casting

Die casting is abbreviated as , which is a casting method in which molten alloy liquid is poured into a press chamber, the cavity of a steel mold is filled at high speed, and the alloy liquid is solidified under pressure to form a casting. The main characteristics of die casting that distinguish it from other casting methods are high pressure and high speed.

Die casting is a method of casting die forging. The die-casting die forging process is a process completed on a dedicated die-casting die forging machine. Its basic process is: the molten metal is firstly cast into the cavity of the mold at low or high speed. The mold has a movable cavity surface. It is pressurized forged with the cooling process of the molten metal, which eliminates the shrinkage of the blank. Loose defects also make the internal structure of the blank reach broken grains in the forged state. The comprehensive mechanical properties of the blank have been significantly improved.

In addition, the rough produced by this process has a surface finish of 7 (Ra1.6), which is like the surface produced by cold extrusion or machining, with metallic luster. Therefore, we call the die-casting die forging process the “extreme forming process”, which is a step further than the “no cutting, small margin forming process”. Another advantage of the die forging process is that in addition to producing traditional casting materials, it can also use deformed alloys and forging alloys to produce parts with very complex structures. These alloy grades include: duralumin super-hard aluminum alloy, wrought aluminum alloy, such as LY11, LY12, 6061, 6063, LYC, LD, etc.). The tensile strength of these materials is nearly twice as high as that of ordinary , which has more positive significance for aluminum alloy automobile wheels, frame and other parts that want to be produced with higher-strength impact-resistant materials.

The molten metal fills the cavity under pressure, and crystallizes and solidifies under higher pressure, the common pressure is 15-100MPa. The molten metal fills the cavity at a high speed, usually 10-50 meters per second, and some can exceed 80 meters per second (the linear velocity of the cavity through the inner gate—the inner gate speed), so the molten metal is filled The molding time is extremely short, and the cavity can be filled in about 0.01-0.2 seconds (depending on the size of the casting). Die-casting machine, die-casting alloy and die-casting mold are the three major elements of die-casting production, and none of them are indispensable. The so-called die-casting process is the organic and comprehensive application of these three elements to enable stable, rhythmic and efficient production of qualified castings with good appearance, internal quality, and dimensions that meet the requirements of the drawing or agreement, and even high-quality castings.

is one of the three major elements of die-casting production. A mold with a correct and reasonable structure is a prerequisite for the smooth progress of die-casting production, and it plays an important role in ensuring the quality of castings (the pass rate of the machine). Due to the characteristics of the die-casting process, the correct selection of process parameters is the decisive factor for obtaining high-quality castings, and the mold is the prerequisite for the correct selection and adjustment of various process parameters. The mold design is essentially to predict the various factors that may occur in the die-casting production. The comprehensive reflection. If the mold design is reasonable, there will be fewer problems encountered in actual production, and the qualified rate of castings will be high. On the contrary, the mold design is unreasonable. For example, the wrapping force of the movable and fixed molds is basically the same when the casting is designed, and the gating system is mostly in the fixed mold, and it is produced on the Guannan die-casting machine where the punch cannot feed after the injection, so normal production cannot be performed. The casting has been stuck to the fixed mold.

Although the finish of the fixed mold cavity is very bright, the phenomenon of sticking to the fixed mold still occurs due to the deep cavity. Therefore, when designing the mold, it is necessary to comprehensively analyze the structure of the casting, be familiar with the operation process of the die-casting machine, understand the possibility of adjusting the die-casting machine and process parameters, grasp the filling characteristics under different conditions, and consider the method of mold processing and drilling. Only after the eyes and the fixed form can we design a mold that is practical and meets the production requirements. As mentioned at the beginning, the filling time of the molten metal is extremely short, and the specific pressure and flow rate of the molten metal are very high. This is extremely harsh for the die casting mold, coupled with the impact of the alternating stress of chilling and heating. All have a great impact on the service life of the mold. The service life of a mold usually refers to the number of die-casting modules (including the number of die-casting modules (including die-casting production) that occur through careful design and manufacturing, under normal conditions of use, combined with natural damage caused by good maintenance, and before they can no longer be repaired and discarded). The number of waste products).

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