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Factors affecting oxidation of aluminum die-casting parts

2023-05-04 16:26:09

Die cast aluminum is made by melting aluminum into a liquid. Inject into the cavity of the die-casting mold at high pressure and speed. After the aluminum water cools down, open the mold to create a molded product. However, generally, die-casting aluminum does not use scrap aluminum, but aluminum ingots. There are too many impurities in waste aluminum, which can affect the work of die casting. Die cast aluminum is a type of pressure casting component that uses a pressure casting machine with a casting mold installed. The aluminum or aluminum alloy heated into a liquid state is poured into the feeding port of the die casting machine, and then die-cast to produce aluminum or aluminum alloy parts with shapes and sizes limited by the mold. Such parts are usually called die cast aluminum.


The main characteristics of die-casting aluminum parts are as follows:


1.  Die cast aluminum parts have good stability. This is a performance that many castings do not have.


2.  Due to the stability of aluminum and its ability to resist oxidation, die-casting aluminum parts are rust resistant and relatively lightweight. It is precisely because of this that many decorative products use die-cast aluminum parts, which can maintain color fastness.


3.  Die cast aluminum parts are very stable, and after multiple tests, it has been proven that aluminum products have a good appearance, and their resistance to wind pressure and weathering is astonishing. Therefore, if aluminum castings are used, they will be more stable. At the same time, the weight of die-casting aluminum parts is relatively light, which can reduce the burden on people and also reduce the danger.


4.  Due to the excellent toughness of aluminum, it determines its plasticity and can be designed into various shapes. Ductility is particularly advantageous. It is precisely because of this that aluminum castings can be used for recycling, which saves materials and has a wider range of applications. Due to this characteristic of aluminum, it also determines its creativity and can be easily modified.


5.  Due to the fact that aluminum is relatively lightweight, it is more convenient for us to use, and there is no pressure for installation or maintenance.



After several days of processing die-casting aluminum parts, they will mold and turn yellow. What is the specific reason for this? After our analysis, there are mainly the following points:

oxidized die casting parts.jpg

1.  After several days of processing, the aluminum alloy should be cleaned, and the moldy (blackening) and yellowing should be the result of oxidation of the cutting fluid. It's not a big problem.


2.  If a similar phenomenon occurs, there may be two reasons: first, the result of the oxidation of the cutting fluid. Second, The product is caused by residual water during cooling after removal.


3.  Mouldy phenomenon: mainly due to inadequate treatment, yellowing phenomenon: oxidation of cutting fluid and concentration of release agent during die casting.


4、 It is a problem with the slag remover during the treatment of aluminum alloy solution. The slag remover lacks fluorine salt content. Check the formula of the slag remover. Another common treatment method is to add 0.2-0.5 sodium fluoroaluminate during the slag removal process of aluminum alloy solution, which can prevent discoloration and mold formation of castings after processing.


5.  Dampness is the main cause.


6.  There is a problem with the spray coating. Over time, the surface of the product oxidizes and causes mold to form.


7.  Aluminum alloy is a bimetallic metal that changes color when encountering acidic or alkaline substances. If the cutting fluid is not selected correctly during mechanical processing, after a period of time, die-casting aluminum will produce yellow, moldy, and even hairy phenomena, which is actually matrix corrosion. One of the solutions is to choose a neutral cutting fluid, and the fundamental method is to form a film on the surface to prevent corrosion.


The equipment components of aluminum or aluminum alloy owned by the casting processing method are aluminum castings. Generally, sand molds or metal molds are used to pour liquid aluminum or aluminum alloy into the mold cavity, so aluminum parts with various shapes and sizes are commonly referred to as die cast aluminum parts. Aluminum castings have some advantages that cannot be compared to other castings, such as aesthetics, light weight, etc., which make them widely favored by users, especially since the lightweight of automobiles, cast aluminum alloy castings have been widely used in the automotive industry. The density of cast aluminum alloys in aluminum castings is lower than that of cast iron and cast steel, while the specific strength is higher. Therefore, using aluminum alloy castings under the same load conditions can reduce the weight of the structure. Therefore, aluminum alloy castings have a wide range of applications in the aviation industry, power machinery, and transportation machinery manufacturing. Aluminum alloy has good surface gloss and good properties in the atmosphere and fresh water, making it widely used in the manufacturing of civilian utensils. Aluminum has good corrosion resistance in oxidizing acid media such as nitric acid and acetic acid, so aluminum castings also have corresponding applications in the chemical industry. Aluminum and aluminum alloys have good thermal conductivity and are used in thermal insulation in chemical production.


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