Brief introduction of coating process and equipment 1. The purpose of painting is first to protect and extend the service life of the workpiece, then to decorate and achieve the purpose of beautiful and pleasant. Third, it is to achieve a special purpose, to achieve special performance. Such as: sound insulation, heat insulation, fire protection, etc. According to different uses and requirements of the coating, the coating is divided into primer, putty, finishing coat and other layers. Primer: it is the lowest coating in direct contact with the painted workpiece body. The function of the primer is to enhance the adhesion between the coating and the body and enhance the protective performance of the coating. Ferrous metals shall be phosphated before removal and non-ferrous metals shall be oxidized before application. Putty layer: for rough and uneven objects, there are many disadvantages in using putty layer, such as trouble in construction, reducing the binding force between coating and objects, etc. the main purpose of finishing coat is to increase the luster of products, which is used for the outermost layer of coating. 2. There are many coating methods, including coating method, dip coating method, air spraying method, high pressure airless spraying method, electrostatic spraying method and electrophoresis coating method. Three. In coating construction, due to the heterogeneity and porosity of single coating, it is rarely used for coating assembly and product material requirements. Primer and finish coats are often used. Intermediate layer and finish can be added as required. The primer layer shall have good adhesion with the workpiece to be coated, and the opposite paint layer shall have good adhesion and rust resistance. The matching principle of primer and top coat is: 1) the dry primer and top coat are well matched; the self dry primer and top coat are well matched; the primer and top coat are well matched. 2) when selecting strong solvent finish, such as nitrocellulose paint, perchloroethylene paint, etc., the primer layer must be able to resist strong solvent without being bitten, such as alkyd paint, epoxy paint, etc. 3) the primer and finish shall have similar hardness and elongation. 4) poor heat resistance when matched with curing primer. 5) the oil degree of primer is shorter than that of topcoat, otherwise, the weather resistance of topcoat is poor, and the drying shrinkage rate of primer and topcoat is different, which is easy to cause cracking of each layer. 6) when multi-layer heterogeneous coating is used, the intermediate layer is often used to make the paint base transition, so as to realize a good combination of the bottom layer and the surface layer. The adhesion of organic coating is related to the properties of product materials. According to the different adhesion, the sequence of metals is as follows: nickel → steel → copper → brass → aluminum → tin → lead iron metals are suitable for almost all types of primers, while magnesium aluminum parts and their alloys are usually passivated primers with zinc chromate as the main body. The surface of the workpiece is effectively pretreated to form a layer of phosphating film or oxide film to improve the adhesion between the substrate and the primer. Then choose the primer with strong adhesion. Red lead primer shall not be used for aluminum and galvanized parts, otherwise it will cause electrochemical effect and reduce adhesion.