What is the effect of voltage on electrophoretic coating

What is the effect of voltage on electrophoretic coating

The voltage of electrophoretic equipment during coating mainly depends on the type of electrophoretic coating, but also related to the polar distance, polar area ratio, tank temperature and other factors. Therefore, before production, it should be tested to select the appropriate voltage plan.

The size of the voltage has great influence on the electrophoretic paint film. In general, when the electrode voltage is high, the electric field force is strong, and the amount of electric accumulation also increases. However, the voltage is too high, the film thickness is too large, and the film layer is rough. After baking, the appearance is very poor. When the voltage is high enough to cross the "damage voltage", the accumulated paint film is broken down, the electrolytic reaction is aggravated, and a lot of gas occurs on the surface of the electrode. At this moment, the coating is very rough, there are large pot pores, so the coating has not reached the intention of decoration and maintenance.

In practice production, there are generally two kinds of electrification methods for electrophoretic coating, namely constant voltage method and constant current method.

(1) Constant voltage method. The so-called constant voltage method is at the beginning of the power. An additional electrophoretic voltage is applied between the north and south electrodes. And kept going until the end. Therefore, the early pulse current is large, constitutes a peak value, and the film thickness increases quickly. With the increase of the thickness of the film, the resistance value of the film increases, and the current quickly weakens. At this time, the increase in the thickness of the film also slows down, after all, it tends to be stable.

The advantage of constant voltage method is that in the process of electrophoresis, the operation is relatively simple, but the method of early accumulation speed is too fast, the paint film is rough, and the appearance is not good after baking. At the same time, the constant voltage method because of the impact current, so begged the capacity of the rectifier power supply to be large. In practice, electrophoretic coating does not require such a large capacity at most times, resulting in a waste of power equipment talent.

(2) Constant current method. Constant current method is that in the process of electrophoretic painting, the current density value is stable, that is, the current density cannot be changed from time to time. In the process of electrophoresis, in order to maintain a certain current density, the voltage needs to be continuously increased, so that the increase of the paint film is uniform. The experiments show that the constant current method can provide the best induction function in the accumulation power and the appearance of the paint film. However, production operations are somewhat cumbersome.

In short, constant voltage method and constant current method have their advantages and disadvantages. From the point of view of induction, it is better to choose the constant current method, but it is difficult to accurately control the current in the process of electrophoresis. Now generally take the long of the two, that is, the early current control method, at the beginning of the electrical accumulation with low voltage, so that the impulse current is not too large, and then gradually increase the voltage to the additional value.

Suzhou Liujin Machinery Equipment Co., Ltd. set up a factory in Taicang City, Suzhou in 2010, the main business: Automobile painting equipment, home appliance painting equipment, electrophoretic painting equipment, liquid painting equipment, powder painting equipment, paint spraying equipment, profile spraying line and other equipment, the company is a production line planning, equipment research and development, system design, equipment manufacturing, on-site installation and commissioning and after-sales service as one of the private science and technology enterprises. We adhere to the "customer-oriented, quality first", regard integrity as the solid foundation for the survival and development of six gold Group, we put customers in the top priority, spare no effort to provide customers with the best products, to help customers reduce costs and increase efficiency, welcome to visit.