1. Alloy elements

　　6063 alloy is an alloy mainly composed of aluminum, magnesium, and silicon, with each element having a certain range of content. Magnesium is expensive. Some manufacturers reduce the amount of magnesium to the minimum allowable content in order to reduce costs. Some even lower the magnesium content below the minimum allowable level. Some factories add waste wires and aluminum pots to the alloy, which is basically not 6063 alloy. As a result, the mechanical strength of aluminum profiles is very low, so low that they can easily bend with both hands, commonly known as being as soft as noodles. This is one of the reasons why aluminum can be cheaper by thousands of yuan.

　　Legitimate aluminum manufacturers have internal standards for alloy composition, which means that each factory has its own smaller range of variation within the content range of various elements. The ratio requirements between aluminum, magnesium, and silicon are very strict, and each factory has its own data that is kept confidential. Only alloys made with qualified formulas can ensure quality, otherwise the quality cannot be improved in future processing.

2. Aluminum alloy melting furnace

　　How to melt the pre made 6063 alloy and what furnace to use are also crucial. Currently, furnaces used in China range from the 1940s to the 1990s, with the worst manufacturers using primitive crucible boilers. There are smelting furnaces that burn coal, oil, gas, and electric heating. Some stoves have chimneys, while others do not. Generally, square furnaces (rectangular furnaces) are commonly used, while advanced ones are circular furnaces. Some circular furnaces can tilt and pour aluminum water. There are one ton, two ton, five ton, ten ton, twenty-five ton, and fifty ton aluminum melting furnaces in terms of tonnage. A more advanced method is to add a static furnace under the aluminum melting furnace. The static furnace is important for preparing 6063 alloy, which can be used to remove slag and gas in this furnace, and then cast aluminum rods for extrusion. The quality of alloys prepared in primitive coal burning furnaces and modern circular furnaces is absolutely different. Generally, no matter what fuel is burned in a furnace, it should have a chimney, and most of the waste gas and residue generated during the combustion process of the fuel can be discharged from the chimney. If all the exhaust gas and waste residue from the chimney are melted into aluminum water, the aluminum rod cast for extrusion will have serious slag inclusion bubbles inside, which is one of the reasons for the poor quality of aluminum and the low price of aluminum.

3. Alloy casting

　　The level of domestic casting equipment is also far apart. The oldest casting equipment in China is iron mold casting at the level of the 1940s, and the advanced one is hydraulic semi continuous casting. The crystal structure of the cast rod in iron mold casting is very poor, and there are a large number of slag inclusions and bubbles in the cast rod. The quality of the cast rod is very poor. Nowadays, horizontal casting (also known as continuous casting) and semi continuous casting are commonly used in factories. Semi continuous casting is mostly driven by steel wire ropes, and the best hydraulic transmission is used. The length of semi continuous casting rods varies, generally ranging from 3 meters, 4 meters to 8 meters. Semi continuous casting is a pit type casting process, where one side is cast while the other is lowered, and cold water is used to cool all sides. Due to the uniform water cooling around, the crystal structure of the casting rod is uniform and fine. But the downward transmission of steel wire rope is not as smooth as hydraulic transmission, and the surface of the casting rod produced by hydraulic casting is smoother than other casting rods. Smooth surface of the casting rod is one of the prerequisites for extruding good profiles. Using other methods to cast the surface of the casting rod is relatively rough. In order to ensure the quality of the profile, sometimes the casting rod is first machined to remove the rough surface. The commonly used semi continuous casting mold nowadays is an advanced, hot top and horizontal casting mold. The characteristics of this casting mold are that it can cast several to dozens of pieces at once, and the casting quality is good. With high-quality 6063 aluminum alloy casting rods, it is possible to produce good aluminum profiles. If the original and outdated casting equipment is used, it is impossible to cast good casting rods, and it is impossible to produce good aluminum profiles. There are many aluminum factories in China that do not have equipment to produce aluminum bars, but instead purchase 6063 alloy bars from electric aluminum factories or other factories. For such aluminum factories, the quality of the aluminum is controlled by the production casting factory, and the aluminum produced is difficult to achieve stable quality. Compared to using advanced casting equipment, using outdated equipment has the advantages of lower investment and lower production costs, which is also one of the reasons for the large price difference in aluminum sales.

4. Profile extrusion

　　There are many types of profile extruders in China, with a wide range of grades, and they are also the most advanced in the world. There are factories that have their own simple extruders, some of which have been modified with plastic extrusion machines, a small number of which are domestically produced, followed by most from Japan, the United States, and Germany, with hydraulic and hydraulic options. In short, there are hundreds of extruders in China with a wide variety. It is generally believed that Japan, the United States, and Germany have better extruders. Good and bad extruders produce the same quality profiles with the same cast rod. We often see aluminum doors and windows in buildings using 6063T5, which is an internationally recognized American grade.

　　The Chinese brand LD31RCS.T5 and RCS both indicate the state, indicating the artificially aged state of air-cooled quenching. The quenching of metals involves a sudden drop from high temperature to low temperature, for example, steel knife blades need to be quenched in water to become hard and sharp, while aluminum quenching also includes water-cooled quenching and air-cooled quenching. 6063 profiles for construction are quenched by air cooling. After quenching, the aluminum material is aged in an aging furnace for a certain period of time. The internal crystallization of the aluminum material is rearranged, and the mechanical strength is significantly improved. Among all metal alloys, only aluminum alloy has an aging state.