Automobile bumper spraying production line process

Plastic bumper spraying is a relatively special production process, which requires high environmental cleanliness. The quality of each process in the entire process must be strictly controlled, otherwise the sprayed products will have many defects, which will seriously affect the product qualification rate. Low will increase the manufacturing cost of the product.

Therefore, the bumper spraying line is a relatively closed and clean production line. The line body must be cleaned every day after production is stopped. The front and rear bumpers of the mini-car are sprayed using a “wet-on-wet, three-spray and one-bake” spraying process, that is, after the primer, topcoat, and varnish are sprayed, they are baked. Some high-end car bumpers use the "three-spray and two-bake" spraying process. "Three-spray and two bake" means that after the primer is sprayed, the primer is also baked. The main function or purpose of each process flow of the automobile bumper spraying production line will be specifically introduced and explained below.

1. Rough inspection of automobile bumper spraying production line
It is an indispensable process to inspect the blanks before loading the parts. The purpose is to prevent defective products from going online, because the parts will inevitably scratch the surface due to bumps during storage. The bumpers with scratches on the surface will inevitably It can't be covered by spraying, and the sprayed product is still a waste product, which is a waste of time, manpower and paint. The slight scratches can be wet sanded with 1,000 to 1,200 mesh water sandpaper, and the serious ones can only be scrapped.
2. Pre-treatment of automobile bumper spraying production line
There are 5 pre-treatment processes, which are an indispensable and important process for bumper spraying and a key link to improve the adhesion of bumper coatings. The function of degreasing is to remove oil stains, mold release agents and other stains on the bumper surface. These stains will seriously affect the adhesion of the paint. After washing with water and pure water, the fine dust on the surface of the bumper can be washed away to prevent particles from being sprayed.
3. Blowing water and water drying on automobile bumper spraying production line
There will be a lot of water droplets on the surface of the pre-treated bumper. If there are water droplets, even very small water droplets will form blisters after painting. This is a defect that is not allowed for painted bumpers. Therefore, it is necessary to blow and dry the pre-treated bumper. The temperature of the moisture drying does not need to be too high, which is a waste of energy. As long as there is no moisture on the surface of the parts, our drying temperature is average. Control at 50～65 ℃ for about 20 minutes.

4. Flame treatment of automobile bumper spraying production line
Flame treatment is to use the high temperature flame generated by the combustion gas of the flame treatment robot to process the surface of the bumper. The flame temperature can reach 2 000 ℃. The flame pretreatment is mainly to burn off the oil on the surface of the bumper and perform surface adjustment to improve the bumper Paint adhesion. This process is basically the same as the pre-treatment. At the beginning, we also used it. After a period of production, the flame treatment was stopped. Due to the test and inspection, the adhesion requirement can be met without flame treatment. The flame treatment process is preferred for the bumper spraying of Japanese and Korean models, and the pretreatment is only manual solvent wiping; but for the bumper spraying of European and American models, the pretreatment method is basically used. , Instead of flame treatment.
5. Electrostatic dust removal for automobile bumper spraying production line
Use antistatic equipment to remove the dust on the bumper surface due to electrostatic adsorption, the purpose is to ensure the surface cleanliness of the bumper before spraying and improve the spraying pass rate.

6. Spray primer, topcoat and varnish on automobile bumper spray production line
The function of the primer spray is to strengthen the adhesion to the PP substrate. Because the PP material is a non-polar polymer material, this primer is specially used for the PP substrate. Without this primer, spray the surface directly The paint film can be peeled off by hand after it dries. The function of the sprayed topcoat is to meet the color requirements required by the design, and to protect the bumper surface from being oxidized by the external environment and not corroded by acid rain, preventing ultraviolet rays from penetrating, and improving the anti-aging ability. The function of the varnish is to increase the surface gloss and make the surface of the product more bright and bright. At the same time, the varnish also has the function of resisting the penetration of ultraviolet rays, protecting the topcoat from corrosion and oxidation, and improving the solvent resistance of the plastic parts. , Chemical resistance.
7. Primer leveling, top coat leveling, and varnish leveling on automobile bumper spraying production line
Leveling, as the name implies, is to make the sprayed paint flow, make the surface of the paint film smooth and make the paint film reach a resprayable state. The leveling effect depends on the volatilization speed of the thinner, and the thinner volatilizes too fast or too slowly , The surface quality of the paint film is not good. If volatilization is too fast, the paint film will dry before it can flow, which will easily cause defects such as orange peel, wrinkles, and poor wetting of the paint film; if volatilization is too slow, the paint film will flow fully and the surface will be smoother. However, sagging, blooming, and color inconsistencies may occur. So it is necessary to control the volatilization speed of the thinner. In the case of very low temperature in winter, the thinner will evaporate slowly. At this time, it is necessary to add a quick-drying thinner to increase the evaporation rate; and in summer, due to the high temperature, the thinner will evaporate quickly, so we will add Slow-drying thinner does not let the thinner volatilize too fast.

8. Baking of automobile bumper spraying production line
The bumper with three coats of paint, the bottom, the surface and the clear, needs to be baked in the drying room after leveling. The purpose is to harden the paint film. The baking time and temperature need to be controlled. If the baking time and temperature are insufficient, the paint film will not cure well, the hardness will decrease, and the adhesion and weather resistance will decrease. The baking time of our bumper is generally 45 min, and the temperature is in the range of 75 to 85 ℃.
9. Forced cooling, inspection and removal of automobile bumper spraying production line
Forced cooling is to cool the freshly baked bumper by blowing cold air to cool the bumper surface to below 40℃, so that the inspector will not be hot when inspecting, and if the surface temperature is still high, there will be paint The feeling that the film sticks to the hand is not conducive to inspection, and it will also print fingerprints on the bumper surface during inspection, which affects the surface quality of the product. The function of inspection is to pick out defective products and prevent them from flowing to the next process. Some products with minor defects can be polished or repaired, while products with serious defects can only be scrapped. The next part is to remove the sprayed and baked bumper from the sliding skid of the spraying assembly line, and transfer it to the special bumper station equipment. Qualified products are transferred to the next process, and unqualified products are repaired or scrapped. deal with.