Washing after oil removal and rust removal, although it belongs to the auxiliary process before painting, it also needs to cause enough attention. After oil removal and rust removal, the surface of the workpiece is easy to adhere to some non-ionic surfactants and CL-. If these residual substances are not cleaned thoroughly, they may cause phosphating film thinning, linear defects, and even phosphating. Therefore, to improve the quality of water washing after oil removal and rust removal, it is necessary to go through multiple rinses, two rinses, time 1-2min, and frequently replace water to ensure that the PH value of water is between 5-7.Coating pretreatment includes degreasing (degreasing), rust removal, phosphating three parts. Phosphating is the central link, degreasing and rust removal is the preparation process before phosphating, so in production practice, we should not only take phosphating work as the focus, but also start from the requirements of phosphating quality, do a good job in addition to oil and rust removal, especially pay attention to the mutual influence between them.
The so-called phosphating, refers to the metal workpiece after containing dihydrogen phosphate acid solution treatment, chemical reaction and in its surface to generate a layer of stable insoluble phosphate film, the film is called phosphating film. The main purpose of phosphating film is to increase the adhesion of coating and improve the corrosion resistance of coating. There are many methods of phosphating, according to the temperature of phosphating, can be divided into high temperature phosphating (90-98℃), medium temperature phosphating (60-75℃), low temperature phosphating (35-55℃) and normal temperature phosphating.The passivation technology of phosphating film is widely used in North America and European countries. The passivation technology is based on the characteristics of phosphating film itself. The phosphating film is thin, generally in 1-4G /m2, the maximum is not more than 10g/m2, the free pore area is large, and the corrosion resistance of the film itself is limited. Some even in the drying process on the rapid yellow rust, after phosphating a passivation closed treatment, can be phosphating film pore exposed metal oxidation, or the formation of passivation layer, phosphating film can play a filling, oxidation, make phosphating film stable in the atmosphere.Drying the phosphating film can play two roles, on the one hand, it is to prepare for the next process to remove the water on the surface of the phosphating film, on the other hand, it is to further improve the corrosion resistance of the film after coating. To establish a coating pretreatment line, the process design must be completed before the design, manufacture and installation of non-standard equipment. Therefore, the process design is the foundation of the production line, and the correct and reasonable route will have a good impact on the production operation and product quality. Used for all kinds of workpiece painting, other models can be customized.