UV coating equipment 、Transfer equipment、Automatic painting、One board device、Microwave equipment

In the traditional sense, coating equipment generally only has coating materials with protective and decorative properties, and these properties are usually unidirectional. Therefore, the surface treatment of the metal before painting must go through degreasing, rust removal, and phosphating (oxidation) to ensure the basic performance of the product.

The quality of the surface treatment before painting (also known as the pretreatment process) is an important link that directly affects the service life of the coating and the decorative effect. The purpose of pre-coating treatment is to remove foreign matter such as oil stains and rust on the surface of the substrate to provide a clean surface suitable for coating, which can significantly improve the adhesion and corrosion resistance of the coating film.

Degreasing methods are divided into physical mechanical methods and physical chemical methods. The former includes wiping method, combustion method and spray method. The degreasing methods used before car painting are mainly physical and chemical methods, including lye degreasing, emulsion degreasing and solvent degreasing. The lye degreasing method mainly removes grease through saponification. When removing non-saponifiable mineral oil, the effect of surfactants is used to help emulsify degreasing. This method is widely used, with better degreasing effect and more economical. The emulsion degreasing method is a mixed solution composed of adding one or several surfactants to an organic solvent, or adding a weak three-point detergent. When the emulsion is immersed or sprayed on the object to be cleaned, the solvent penetrates the grease to make the grease particulate, while the surfactant emulsifies and disperses the grease particulate in the cleaning solution, thereby removing the grease. There are usually two solvent degreasing methods: immersion method and trichloroethylene cleaning method. The dipping method is a method of immersing the cleaned object in an organic solvent, stirring or manually washing and degreasing. Commonly used solvents are gasoline, xylene, acetone and so on. The trichloroethylene cleaning method is also called the dry cleaning method. Usually, the trichloroethylene is heated and trichloro vapor is used to degrease the cleaned objects.

Rust removal is to remove the oxides and hydroxides generated on the metal surface. The method of rust removal is usually selected according to the color, generation state and procedure of the rust. Derusting methods can be divided into physical derusting and chemical derusting. There are two types of physical descaling: manual descaling and mechanical descaling. Chemical rust removal is commonly used pickling rust removal method. Manual rust removal usually uses tools such as shovel, scraper, rust hammer, wire brush and emery cloth, so the labor intensity is high, the work efficiency is low, the quality is unstable, the labor protection is poor, and it is not suitable for application in automobile manufacturing. But it is still one of the easiest and most commonly used methods in the automotive maintenance industry. Commonly used tools for mechanical rust removal include hand lifted electric grinding wheels, electric brush wheels, pneumatic brushes and pneumatic rust removal wheels with needle beams. At present, mechanical rust removal mostly uses sandblasting and shot blasting. Chemical rust removal is commonly used pickling method, that is, the metal is immersed in an acid solution, so that the oxide and hydroxide attached to the metal surface undergo a chemical reaction and dissolve in the acid solution to remove rust.

Phosphating treatment is a method in which the metal surface undergoes a certain chemical treatment to form an insoluble, phosphating double salt protective film on the metal surface. Phosphating treatment is widely used in covering parts, cabs, body panels, etc. in the automobile industry. As a surface treatment before painting, it can increase the adhesion and corrosion resistance of the coating film. The commonly used phosphating films are zinc phosphate type and manganese phosphate type. The zinc phosphate film is thin, dense and smooth, has certain corrosion resistance, and can withstand certain deformation, but the bath is not stable enough and maintenance is more complicated. The manganese phosphate type has the characteristics of stable bath and convenient maintenance.

Precautions for metal paint spraying

(1) After spraying metallic paint, dust must be removed before the next operation.

(2) Metallic paint mainly plays a role of covering. Do not spray too thickly, otherwise the paint color will be too dark or too dark.

(3) Stir evenly. Metal particles such as aluminum powder in metallic paint are easy to settle on the bottom of the paint can, so metallic paint needs to be thoroughly stirred before spraying than ordinary natural paint.

(4) The matching thinner and the corresponding dilution ratio must be selected according to the instructions provided by the paint manufacturer, and the viscometer should be used correctly to master the required viscosity to ensure that the paint color meets the requirements.

(5) Use of spray gun. When spraying metallic paint, uniform paint film thickness is very important. The nozzle should be aligned with the spraying surface at a vertical angle, and the distance between the two should be kept between 5-20cm, and the spray gun should be moved straight at a uniform speed and avoid moving the spray gun in an arc manner. Each reciprocating spraying requires 50% overlap area, so that a fixed color can be obtained. When you need to adjust the paint output of the spray gun, you can pull the trigger of the spray gun to the end, and use the moving speed of the spray gun to increase or decrease the thickness and dryness of the paint film.

The main purpose of phosphating treatment for primer before painting is to improve the adhesion of the paint film and the corrosion resistance of the coating system, so the focus is on the performance of the paint film. Generally, the phosphating quality inspection indicators include film appearance, film thickness and performance after matching with paint film. The appearance of the film should be a uniform, dense and complete phosphating film. For light iron phosphating, its appearance should be a uniform, dense and complete phosphating film, and for light iron phosphating, its appearance should be a complete red and blue color film.