Why is the film thickness related to the success or failure of the coating process?

For coating construction, the film thickness is the most important control factor in the coating process, and its significance lies in:

 (1) Prevent coating defects caused by improper film thickness. According to experience, more than half of the appearance defects of the coating in the field production are caused by improper control of the coating film thickness. Some common coating defects such as sagging, thin paint layer and exposed bottom color are directly related to the out of control of film thickness, and some defects are also indirectly related to this. For example, if the film thickness of the first layer of adhesive primer sprayed on the bumper is not enough, the adhesion of the entire coating will be reduced. At the same time, if the film thickness of the primer fails to meet the requirements, its conductive effect will also be reduced, which will cause the transfer rate of the coating to decrease when the first layer of color paint is sprayed by electrostatic spraying, and finally lead to the lack of color paint.

 (2) Help adjust appearance indicators. Common paint film appearance indicators such as gloss, color difference, orange peel, DOI, etc. need to be based on film thickness control. The above indexes are obviously affected by the film thickness, especially the film thickness of the top coat. Therefore, it is necessary to take the film thickness as the most important control factor in the whole coating quality control.

(3) Cost control. In addition to the quality cost reflected by the influence of film thickness control on coating quality, about half of the main cost of coating is occupied by coating. Accurate film thickness control is not only conducive to the stability of coating quality, but also conducive to the saving of coating.

Statistics show that when the same equipment is used for spraying, whether the film thickness is accurately controlled will lead to a difference of more than 25% in the coating consumption. At present, the robots used in China are mainly Japanese Iwata or Mitsubishi robots, which were introduced earlier and have poor control accuracy; Abb, FANUC, Motoman, DURR and other multi axis robots are widely used in the new coating line.