In numerical control processing, aluminum casting is usually made by metal mold. The metal material aluminum and aluminum alloy have good fluidity and plasticity, but it is very easy to blacken in the process of application. Today, let's talk about why the aluminum surface is blackened in Dalian numerical control processing. What are the reasons for this?
1. The structural design is not scientific. The aluminum alloy die castings were not treated correctly after cleaning or pressure inspection, which created a standard for the aluminum alloy die castings to get mildewed and blackened, and accelerated the formation of mildew.
2. Logistics warehousing management is not timely. When aluminum alloy die castings are stored at different heights in the warehouse, their mildewing conditions are different.
3. Internal structure of aluminum alloy. Many aluminum alloy die casting manufacturers can not completely clean and tidy without other cleaning treatments or simply flushing with water after the die casting and machining processes. The surface of die casting aluminum is left with mold release agent, cutting fluid, saponification fluid and other etching substances and other stains, which accelerates the growth of mold spots and blackening of aluminum alloy die castings.
4. External environmental reasons of aluminum alloy. Aluminum is an active metal material, which is easy to be oxidized and blackened or mildewed under certain temperature and environmental humidity standards. It is affected by the characteristics of aluminum itself.
5. Improper selection of cleaning agent. The selected cleaning agent has strong etching, resulting in etching and oxidation of die cast aluminum.
The blackening of aluminum surface is caused by the oxidation of aluminum products. It is recommended not to remove it. The aluminum oxide is relatively stable in the air. It is difficult to re oxidize. It can protect the aluminum inside from oxidation. Aluminum: silver white light metal. It is malleable. Goods are often made into rods, sheets, foils, powders, ribbons and filaments. It can form an oxide film to prevent metal corrosion in humid air.
When heated in air, aluminum powder and aluminum foil can burn violently and emit dazzling white flame. It is easy to dissolve in dilute sulfuric acid, nitric acid, hydrochloric acid, sodium hydroxide and potassium hydroxide solution, but difficult to dissolve in water. The relative density is 2.70. The melting point is 660 ℃. The boiling point is 2327 ℃. Aluminum is the most abundant metal element in the crust, ranking the third after oxygen and silicon. The development of the three important industries of aviation, construction and automobile requires that the materials have unique properties of aluminum and its alloys, which is greatly conducive to the production and application of this new metal aluminum. It is widely used.
