Unveiling the complete process and technological innovation of automotive painting technology!

If the engine is the "heart" of the car and the body is the "skeleton" of the car, then the painting process is the "skin" and "armor" of the car. This article will start from the complete process of "pre-treatment electrophoresis intermediate coating topcoat post-treatment", and combine technological innovations such as no intermediate coating, water-based paint, and robot spraying to unveil the mysterious veil of this "pearl".

1、 Pre processing: Precision engineering for bathing the car body

The first step in painting is "pre-treatment", which is equivalent to a deep cleaning and protective preparation for the vehicle body. Untreated metal car body surfaces may retain impurities such as grease, rust, dust, etc. If directly coated, the adhesion between the coating and the car body will significantly decrease (possibly less than 50%), leading to later peeling. The core process of pre-treatment includes four steps: degreasing, water washing, surface adjustment, and phosphating, each of which requires precise control.

2、 Electrophoresis: Wearing the first layer of "invisible armor" on the car body

After the pre-treatment is completed, the vehicle enters the electrophoresis tank, which is the core link of "anti-corrosion" in the painting process. The full name of electrophoresis is "cathodic electrophoretic coating". Its principle is to immerse the vehicle body as a cathode in positively charged electrophoretic paint (mainly composed of epoxy resin). Under the action of direct current (voltage 200-350V), the electrophoretic paint particles will move towards the vehicle body and deposit on the surface, forming a uniform coating with a thickness of 18-25 μ m. This layer of coating is called the "primer", which is like a layer of "invisible armor" that can cover all gaps and corners of the vehicle body (including the interior), and its anti-corrosion performance far exceeds traditional spraying processes.

3、 Mid coat and Topcoat: Upgrading from "Functional Layer" to "Aesthetic Layer"

After electrophoresis, the car body needs to be coated with two layers of "intermediate coat topcoat" in sequence, with the former enhancing its functionality and the latter improving its appearance. The intermediate coating (thickness 25-35 μ m) is mainly made of polyester resin or acrylic resin, which is used to fill the small pores of the electrophoretic layer (porosity reduced from 5% to below 1%), enhance the anti stone impact performance of the coating (able to withstand the impact of 500g steel balls falling from a height of 1 meter without cracking), and provide a smoother adhesion surface for the topcoat.

Topcoat is the finishing touch of the painting process, consisting of two layers of "color paint clear coat". The function of colored paint is to protect it from UV rays and acid rain erosion (with a weather resistance of at least 5 years), while providing high glossiness (gloss value ≥ 90).

4、 Technological Innovation: Robots, Waterborne Paint, and Digitization Lead the Transformation

Robot spraying is a core breakthrough in recent years - through 6-axis linkage (which can simulate the flexible movements of human wrists) and laser positioning (with an accuracy of ± 0.1mm), it can achieve "fully automated, high-precision, and high-efficiency" spraying.

Replacing solvent based paint with water-based paint is a significant innovation in the field of environmental protection. Traditional solvent based paints contain 40% -60% organic solvents (such as toluene and xylene), which volatilize to form VOCs (volatile organic compounds), polluting the air and endangering workers' health. Water based paint uses water as a diluent (VOCs content<10%), which can reduce organic solvent emissions by more than 90%.