Aluminum Alloy Wheel Coating Production Line and Process Features

Introduction to Aluminum Alloy Wheel Coating Production Line Combined with Types of Paint and Process Features

Main Process Flow of Coating Production Line
1. Pre-treatment:
   - Aim: To remove oil, impurities from the wheel surface and form a protective film to provide a good base for subsequent coating.
   - Process: It usually includes pre-degreasing, degreasing, water washing, oxide film removal, passivation, etc., all using spray methods.
2. Primer Spraying:
   - Commonly using gray powder of polyester/epoxy mixture for spraying, which can be done manually, with fixed spray guns, or by robotic automatic spraying.
3. Color Coating:
   - Using paints or water-based paints for spraying. The primer can protect the wheel from corrosion and cover the roughness of the casting surface, increasing the smoothness of the wheel surface.
4. Clear Coat Application:
   - Using transparent powder or transparent paint for spraying. Transparent paint has issues with environmental impact and recycling, and is being replaced by transparent powder. Common transparent powders include polyester transparent powder and acrylic transparent powder, with the latter having better gloss and anti-aging properties and becoming more popular.

Different Types of Paint and Their Process Features
1. Metallic Paint:
   - Process Features: Metal powders are added to the paint base. When light hits these metal powders, they reflect, making the wheel appear to be shining like metal. The distribution of metal powders needs to be controlled evenly during spraying to achieve a good visual effect.
   - Application: Suitable for scenarios where the appearance of the wheel is highly important.
2. Powder Coating:
   - Process Features: The powder is electrostatically attracted to the wheel surface and then cured at high temperature to form a hard, smooth coating with excellent weather resistance, wear resistance, and corrosion resistance. The thickness of the sprayed powder is generally controlled around 100 micrometers, which can effectively enhance the appearance of the wheel as well as its resistance to stone impact and corrosion.
   - Application: Suitable for coating aluminum alloy wheels.
3. Water-based Paint:
   - Process Features: It has excellent environmental performance, being non-toxic and harmless, and posing no threat to the environment and human health. The water-based solvent can reduce the viscosity of the paint, improving the leveling and spraying effects of the paint.
   - Application: With the increasingly strict environmental regulations, its application is becoming more and more widespread.
4. Acrylic Baking Enamel:
   - Process Features: Used in the spray painting process to treat color paint and clear paint, it can effectively eliminate the color difference that may occur in wheel spray painting.
   - Application: Commonly used as the final step in the spray painting process to enhance the quality of the coating.

Equipment Composition of Coating Production Line
1. Pre-treatment Equipment:
   - Using a full spray cleaning method, composed of multiple processes. The inner walls of the process tanks, the inner walls of the sealed rooms, and the circulation pipelines are all made of stainless steel. It includes spray treatment tanks, sealed rooms, oil-water separators, filters, and phosphating sludge removal devices.
2. Primer Powder Spraying Equipment:
   - The illumination in the powder spraying room should not be lower than 300Lx, with variable frequency air supply. The temperature control is 20±2℃ in winter and 26±2℃ in summer, and the air supply temperature in the leveling room is 60℃. The main equipment includes a stainless steel powder spraying room, powder supply system, high-voltage electrostatic spray guns and control systems, and powder recovery system.
3. Color and Clear Coat Spraying Equipment:
   - The air supply cleanliness in the spray painting room is 10,000 grade, with an illumination range of 800Lx-1000Lx. The air supply and exhaust volume of the spray painting room can be adjusted to ensure the slight positive pressure in the spray painting room and energy-saving requirements. The main equipment includes a spray room, air supply system, spray guns and control systems (including color-changing systems), and waste paint recovery systems.
4. Drying and Curing Equipment:
   - The paint drying oven and powder curing oven use a bridge-type drying structure, which has the advantages of preventing heat leakage and good insulation to achieve energy-saving requirements. The main equipment includes a drying room, cooling room, temperature control system, and exhaust gas treatment system.
5. Conveying Equipment:
   - Ordinary type overhead conveyor is used for pre-treatment equipment. The conveying speed regulation uses variable frequency, with oil collection pans installed throughout the line. The spray powder room, spray painting room, and drying equipment use a ground conveying system with variable frequency speed regulation and stepless speed control.

Process Layout Features of Coating Production Line
1. Zonal Layout:
   - Like the body painting line, the aluminum wheel coating line also uses a zonal method to ensure the different cleanliness levels required in each area of the painting workshop. Generally, the spray painting room and spray powder room should be arranged in the same area, and the drying room should be arranged in the same area. The drying room adopts a multi-trip drying method.
2. Mechanical Conveying Methods:
   - Ordinary Overhead Conveyor:
   - Suitable for spray painting or powder spraying, automatic spraying can ensure the quality of product coating. The process layout is flexible and convenient. Drying can use a multi-trip drying room or a drying room with wheels arranged horizontally in parallel.
   - Ordinary Circular Ground Conveying Machine:
   - Suitable for the cleaning process of pre-treatment. Depending on the production volume, 2-3 workpieces can be hung. The cleaning effect is good, and the hanger is simple and applicable.