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How To Deal With Moldy Aluminum Die Castings

September 26, 2021

Aluminum Die Castings

In the die-casting aluminum industry, the oxidation of aluminum alloy die-castings is commonly known as "mold", "mold spot", "mold powder", and "surface mildew". Not only will it cause a large number of waste products to increase costs, but also problems such as return due to delayed delivery or moldy products at the customer. Therefore, the oxidation of aluminum alloy dies castings cannot be ignored.


Causes of oxidation of die-cast aluminum

On the surface, it looks like a white velvet, just like everyday things are moldy, but after wiping off, small gray-black spots appear underneath. This is a phenomenon that occurs when aluminum is oxidized. Next, we analyze the reasons for the oxidation of die-cast aluminum:

1. Many manufacturers do not do any cleaning treatment after die-casting and machining processes, or simply flush with water. This method leaves a lot of dirt on the surface of die-cast aluminum, such as release agent, cutting fluid, saponification fluid, etc., which are corrosive. The substance accelerates the growth of mildew on aluminum alloy die castings.

2. Aluminium is a lively metal, which is easily oxidized under certain temperature and humidity conditions, that is, moldy. Therefore, the inventory of aluminum parts must be kept dry in the inventory environment.

3. The choice of cleaning agent will also affect the mold growth of die-cast aluminum. Acidic cleaning agents such as "aluminate removal" are very popular now. Some people use alkaline cleaning agents because die-cast aluminum has not only aluminum but also silicon, copper, magnesium, and other elements, among which silicon content is relatively high. The silicon element makes the aluminum parts have a strong adsorption force to the alkaline cleaning agent, especially the phosphorus-based alkali additives, which makes the subsequent rinsing impossible, and the oxidation corrosion of the aluminum to the alkali is relatively slow. The main component of "aluminate removal" is acid, which emits gas through a chemical reaction with the aluminum substrate, and the gas is generated and discharged from the surface of the workpiece to separate the oil and dirt from the workpiece. It looks good on the surface, but in fact, the product has been corroded by a layer. If the subsequent rinsing is not thorough, there will be a lot of acidic substances remaining on the aluminum parts, which will directly corrode and oxidize the aluminum parts.


Commonly used methods to solve die-cast aluminum oxidation

1. Generally, the finished aluminum parts must be sealed and packaged to prevent the substances in the air from affecting storage and oxidation. If it is a cleaned aluminum part, it must be dried. It must be thoroughly dried when packed in a bag.

2. Oxidation and mildew affected by the inventory environment are generally different due to different placements and different upper and lower heights. The amount of oxidation that occurs is different. You can analyze whether the inventory is poor according to this phenomenon.

3. Some manufacturers recommend the use of passivation film and other processes. In fact, do a good job in inventory environmental management, and the aluminum parts themselves can withstand preservation during the cleaning process.

4. Unless there are special requirements, do not use acid cleaning agents. And don't believe that using alkaline cleaning agents will not affect you, the effect of alkaline is relatively slow. Now the better choice on the market is a neutral and environmentally friendly cleaning agent, which not only cleans thoroughly, is easy to rinse, and does not corrode the surface of aluminum die castings, but also can largely avoid aluminum die castings caused by acidic and alkaline cleaning agents. Oxidation problem.


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