The appearance forms of aluminum alloy casting hub mainly include coating and electroplating. Painting colors include sports silver and silver gray. Electroplating process can have a great impact on the natural environment, and the current application is gradually reduced. Coating is the dominant process in aluminum alloy casting wheel hub of motorcycle. Coating in aluminum alloy casting wheel hub is the last step, and the main purpose is to improve the beauty and corrosion resistance of casting wheel hub. In order to ensure the coating quality, the production environment must be kept clean and dust-free during the production process. Manual spraying and automatic spraying are two coating methods. Through manual spraying, the thickness and quality of the coating can not be effectively controlled. Under automatic spraying, the coating thickness can be guaranteed and has high precision. The coating thickness needs to be adjusted automatically in combination with technical requirements. Air spray gun and electrostatic spray gun are two forms of spray gun, but air spray gun is only applicable to spray paint.
The painting process mainly includes three aspects: ① in the pretreatment, the basic process is spraying primer, color paint and transparent powder; ② In the special pretreatment, there are mainly spraying color paint and transparent powder; ③ In the last pretreatment process, transparent powder is mainly sprayed, but the corrosion resistance of the latter two processes is relatively poor. At this stage, the process and equipment are mainly automatic production lines for pretreatment, bottom powder spraying, color paint spraying and transparent powder spraying. The automatic production line of coating is mainly composed of drying, pretreatment and other parts. The traditional system will place the aluminum alloy casting hub horizontally according to the ground chain mode, and also install the recovery powder system and replacement system. “High speed electrostatic spray gun technology” and electrostatic spray gun technology can be used in automatic coating equipment. However, the production efficiency of the production line is relatively high, and the coating needs to be saved to ensure environmental protection. Therefore, aluminum alloy casting hub is the latest development trend.