Interpretation of common problems of die casting aluminum alloy (1)

First, the interpretation of the common problems of die casting aluminum alloy:

1. Overview: On a global scale, the United States, Europe and Japan are traditional die casting powers, especially reflected in the pillar industry represented by the automobile, they have a long history of development, large coverage of shopping malls, and have accumulated rich experience in many aspects, especially the competitiveness of shopping malls constitutes a position that is difficult to shake for a while, its central competitiveness is a strong support, and the sales of passenger cars in China lead the world. Foreign cars with intellectual property rights occupy a great advantage and proportion, which is a kind of pressure on our country and also a kind of external impetus; At that time, China's aerospace industry, because of the tight blockade of foreign countries, is difficult to step in the sense of self-reliance and independence, but today it is flourishing! The author has been engaged in the aviation industry for nearly 40 years, from editing a number of aerospace and national military materials and process standards, to participating in the expert evaluation of national aviation scientific and technological achievements for many years, all of which have personally experienced this historical process. After retirement, through participating in the research practice of European and American orders for many domestic enterprises, I deeply realized the future of reform and opening up. China's light alloy casting skills and industries have been greatly developed, production capacity, scale and quality levels have been greatly improved, which because the aviation aluminum alloy casting skills started early, a high starting point, the country's development and focus on its skewed, so in the favorable situation of military transformation, it has played a certain supporting effect on the broadening of the field of China's period.

2, the commonality of die casting aluminum alloy standards:

As far as the chemical composition standard of die-casting aluminum alloy is concerned, because of the process characteristics of die-casting molding and condensation, the statistics of the standards of relevant countries so far indicate that the primary alloy series is basically the same.

3, Discussion on the improvement of the quality level of die casting aluminum alloy:

The selection of AI-Si alloy as the main body of die-casting aluminum alloy is decided according to the die-casting process and forming condensation characteristics. So far, they are also the most widely used in die-casting aluminum alloy and the largest alloy varieties with the highest output. It is because of the relatively concentrated problems exposed, many common problems must be paid attention to.

First, analysis of the shortcomings of holes in die casting parts:

Aluminum alloy in liquid state, it reacts with water in the air to produce Al2O3 and H2, the Al2O3 structure is loose, and the specific gravity is similar to aluminum, simply suspended in liquid aluminum and has a strong adsorption effect with H2, which can form the adsorption center. A large number of recycled aluminum in the die-casting aluminum alloy O melting, if the pre-treatment is not standard must pose a danger, this point in the author's investigation of the Japanese company Guangzhou Honda casting production, the pre-treatment of recycled aluminum is very strict and standard, the author is impressed! The Si element is the main element in Al-Si alloy, which is not only more than two times higher than the melting point of aluminum, but also lighter than aluminum, so in order to homogenize it in melting, it is necessary to stir vigorously at high temperature, and it is also necessary to roll into gas and constitute oxidation. In addition, the participation of Si element reduces the solubility of H2 in aluminum liquid, and the viscosity and surface tension also increase. Prevent the formation and floating of bubbles in liquid aluminum, which are the causes of the shortcomings of Al-Si die-casting alloy castings, for this reason, aluminum alloy smelting squadron alloy cleaning process pay special attention to the past concept is degassing, many of the shortcomings of the failure analysis indicated, now the cleaning process are purified treatment, that is, the cleaning process, both for alloy degassing and slag removal, Otherwise, the gain is not worth the loss, and the purification treatment device of the alloy is further optimized.

It introduces pure argon through the distribution hole on the rotating graphite rotor with the end head, and introduces the refining flux into the swirling vortex of the refined alloy liquid with argon and oxygen as the carrier, thus achieving the effect of both gas and slag removal.

Second, the interpretation of intermetallic compounds and hard points in die casting:

Hard points are often found in the machining process of die-casting alloys with Al-Si system as the main binary system, especially Al-Si-Cu system alloys, which are mostly intermetallic compounds, mostly ternary ones, and there are also primary crystalline silicon particles.

The composition of these shortcomings often occur in aluminum alloy die casting conditions, one is that the pre-treatment of die casting is not standard, the refining and purification process in the process of sintering is not thorough, these dangers are particularly sensitive in the production process of die casting, and the same similar alloy is not easy to appear in the gravity casting, moreover, In the production process of die casting, the size and proportion of the gate cross-sectional area, its touching velocity and the disturbance in the formation of the eruption, if the design of slag discharge and exhaust system is not in place, it will also lead to shortcomings, it should be emphasized that in all aluminum alloy series, Al-si system is also sensitive to gas residue, so the melting of die casting alloy ingot and the pretreatment of raw materials need to be paid attention to. The incoming inspection of die-cast alloy ingot in die casting also needs attention.

Third, the interpretation of the shortcomings of the air tightness problem of the die casting under pressure:

Pressure and water pressure, oil pressure and other pressure resistant parts in the die casting because of the lack of air tightness leakage occurs, especially the shape of messy, uneven wall thickness of the die casting similar shortcomings are also common, our experience is: First of all, it is necessary to make a good trial production of die casting, whether the mold design and manufacturing can be satisfied with the quality of die casting is up to standard and stable, more importantly, look at the metallurgical quality of the test piece, the surface quality of the die casting part and the internal quality results of the perspective, and there must be 3-5 batches of production trial production of stable results (a few) ultimately need to pass the die casting processing assessment. Among them, the qualified inspection of the mold is the most important thing, which touches on the design of the runner in the mold debugging, the analysis of the heat balance of the cavity, the design of the slag exhaust duct, and the adoption of circulation, water cooling, coating spraying, partial cooling and other methods, if the requirements of the air tightness of the die casting is a crucial skill requirement, the adoption of various methods is still uncertain. In order to ensure the quality of the pressing part, it is necessary to choose moisturizing treatment to solve the pressure leakage part is an effective way.

Wuxi Dahao Hardware Manufacturing Co., Ltd. specializes in: aluminum die casting manufacturers die casting aluminum alloy precision aluminum die casting