A valve is a device used to control the direction, pressure, and flow rate of a fluid in a fluid system. It is a device that allows the medium (liquid, gas, powder) in piping and equipment to flow or stop and can control its flow. The valve product market, especially pneumatic valves, is developing in the direction of high technology content, high parameters, and strong corrosion resistance. This development direction also puts forward higher requirements for the coating of valves. Electrostatic spraying technology has also been widely used in the valve industry in recent years, but different materials and processing techniques require different characteristics in the selection of electrostatic powder spraying equipment. It not only pays attention to the conventional optimization of electrostatic spraying equipment technology, environmental protection requirements, powder recovery rate, powder loading rate, etc., but also pays attention to the coating required by its unique industry development and market conditions for processing different types of workpieces.
The following is an explanation of the precautions of the valve in electrostatic spraying
1. Pre-treatment process. After casting and molding, sandblasting is used to treat the oxide scale and molding sand on the surface. Try not to use shot blasting. Because the valve requires high accuracy, especially the inside of the valve, there will be some local spots that cannot be cleaned by shot blasting. Sandblasting can better control the surface roughness and smoothness. But its slower efficiency is its disadvantage.
2. If the surface of the valve is partially oily before entering the powder spraying chamber, the first thing that appears is that the oily surface coating becomes obviously thinner. Secondly, the coating film has poor adhesion and is easy to fall off. Finally, the color difference of the coating film is obvious.
3. Valve castings are generally thicker and require sufficient preheating time. This is generally easy to overlook. The overall design of the powder spraying assembly line must be reasonable to ensure that the valve has enough time to preheat and run in the oven.
4. For large-scale outdoor valves, it requires heavy anti-corrosion. The thermosetting powder should not be used for the sake of cheap internal powder. Pure epoxy resin powder should be used, and the manufacturer is required to issue an authoritative inspection report. Under the same coating method, if the indoor powder coating is used outdoors, the service life of the coating film is usually 6 months.
5. Valve coating problem. Many manufacturers pay attention to the appearance and color, but do not really pay attention to the quality of the coating film. In fact, the color is mainly related to the powder, but also has an important relationship with the spraying method.
