company news about The whole process of electrophoretic coating

The entire electrophoretic coating process can be divided into four parts: ● Pre-treatment ● electrophoresis ● Post-washing ● drying The whole system process is shown in the following figure: After degreasing, the workpiece is modulated and phosphating, so that a uniform and dense phosphating film is formed on the surface to prepare for entering the electrophoretic tank. Into the tank, direct current is passed between the workpiece and the corresponding electrode. Under the action of an electric field, paint particles are adsorbed to the workpiece and deposited on the surface. When the film reaches a certain thickness, electrophoresis stops. At this time, remove the workpiece from the tank, rinse off the floating paint after washing, send it to the oven for curing. one Pre-treatment The process of degreasing, pickling, rust removal (if necessary), surface conditioning, phosphating to prepare for the next step of electrophoresis is called pre-treatment. In order to obtain a good electrophoretic coating, cleaning and phosphating are very important links. Phosphating usually uses iron and zinc series phosphating fluids, and the treatment process includes spray and impregnation. Mainly applicable to steel substrate. The simple steps of pre-treatment can be expressed as follows (for steel parts, for example) : pre-degreasing → degreasing → water washing → Rust removal (if necessary) → deionized water washing → surface conditioning → phosphating → deionized water washing 2. The electrophoretic workpiece shall enter the electrophoretic tank after pre-treatment. The state of the workpiece before entering the tank must ensure that the surface of the workpiece is free of oil and rust, the phosphating film is uniform, the surface temperature of the workpiece should be below 40℃, and the workpiece should be completely dry or wet before entering the electrophoretic tank. Uneven wetting and drying may lead to patterns or markings on the paint film. The components of the electrophoretic tank system and their functions: ● DC power supply (rectifier) - provides direct current to enable electrodeposition. ● Main circulation system - including circulation pump, jet pipe and filter, to ensure that the tank mixture is uniform, while removing particulate pollutants and impurities in the tank. ● Ultrafiltration system - controls the conductivity of the tank fluid, provides ultrafiltrate after cleaning the workpiece, and recovers the float paint. ● Heat exchanger - Control tank temperature. Control of the electrophoresis tank related system: 2. After the workpiece is washed out of the ultrafiltration, the ultrafiltration is used to wash off the floating paint attached to the surface of the paint film. The floating paint can be recovered to the tank, which improves the utilization rate of the paint liquid and ensures the smooth and beautiful paint film. Through the circulation system, the cleaning solution is also recovered to the tank solution, so that the painting efficiency can reach more than 95%. The use of closed cycle cleaning can effectively remove and recover the floating paint, so that the paint utilization rate. The ultrafiltrate obtained by ultrafiltration (containing low molecular weight substances such as deionized water and solvents) is an integral part of the cleaning solution. The cleaning area includes a series of separate spray cleaning rooms or dip cleaning rooms. The first few steps are cleaned with ultrafiltrate and cleaned with fresh deionized water. There is sufficient drain time between each wash. After a wash, almost all of the wash can be recovered. Most of the electrophoretic coating lines use automatic air dryer to remove the moisture on the surface of the paint film before the workpiece enters the drying room to prevent the formation of water marks. 3. After drying, curing, cleaning and drying, the workpiece enters the drying room, and the paint film achieves its performance through cross-linking curing. Different electrophoretic coatings use different baking temperatures, usually at least 20 minutes baking time at the specified process temperature. Most ovens have different temperature zones. This design is conducive to the workpiece through different temperature zones, gradually remove volatile substances, prevent solvent spots and water marks, so that the paint film reaches the level, get a good appearance of the paint film.