The baking paint treatment can give metal various colors and different textures. It is painted on the metal surface as a surface treatment, which has both protective and aesthetic functions.
What is Paint Treatment Technology?
Baking varnish refers to the rust-proof, stereotyped and glossy varnish on the substrate that has been polished to a certain degree of roughness, sprayed with several layers of paint, and then baked at high temperature to shape.
Spray some paint or paint on the metal surface. Through the painting operation, the metal surface will have a relatively tight protective film to protect the metal from being oxidized or corroded, and allow the metal to obtain richer colors, thereby improving the aesthetics of the metal.
The standard procedure for painting includes an anti-rust primer, a second coat of primer, a topcoat, and gold oil. A total of eight layers of paint are used to ensure the quality of the paint.
Why Bake at a High Temperature?
High-temperature baking and setting especially refer to the action of baking the car paint at a high temperature of 170 to 200 degrees after the new car manufacturer has painted the new car. This process is called baking paint.
What is Cold Paint?
However, there are few general paint factories on the market that have high-temperature paint-baking equipment that can reach 170-200 degrees. Even because the vehicle has been assembled with many accessories and the owner's personal belongings, it is even more impossible to paint at high temperatures, so it leaves the factory. The subsequent varnishing action is the so-called cold varnishing.
Cold baking paint is to use paint or gold oil as a bridging agent by mixing hardeners so that the paint or gold oil can chemically change and become dry and hardened, to achieve the same effect as high-temperature baking paint. The paint factory will also bake and strengthen it at a temperature of about 80 degrees. This process is called cold paint.
Cold-baking paint technology cannot make the paint hard like high-temperature baking paint, mainly to make the paint dry quickly and reduce energy consumption. As for the time and temperature of cold baking, each company has different practices. Usually, the paint is baked in several stages of temperature to prevent the deep paint from not being completely dried.
Steps to Paint the Whole Car:
Step 1: Polishing and Dedusting
After a car is sent to be painted, if the whole car is baked, whether it is a big car or a small car, the first step is to use a pneumatic turntable to remove the old surface paint, wax stain, and oil on the painted surface. It's just that the turntable used for waxing is connected to a sponge, but sandpaper is used to remove the paint. Sandpaper is a very important procedure in the process of baking paint. Because of the different numbers, the thickness of the surface of the sandpaper is also different. The smaller the number, the thicker the surface of the sandpaper. For polishing sandpaper, if you want to deal with damaged parts of the car body, such as dents, scratches, etc., the number of sandpapers used is relatively small, usually 100-150. If the paint condition is not too bad, use 600 grit sandpaper.
Step 2: Galvanized soil
The body will inevitably have dents due to collision. If the collision is not serious, the painted surface can be leveled by filling soil. Of course, if it is a big collision, the whole sheet metal must be replaced. At present, the soil filling is divided into two parts. In the past, only a layer of pure soil was needed to fill the soil. However, when the galvanized steel sheet is gradually used widely if the traditional soil filling is still used, it will be found that under high temperature, the traditional soil filling and the galvanized steel sheet will not be tightly joined, and peeling and blistering will occur at high temperatures. Therefore, the galvanized soil filling will gradually replace the traditional single-step soil filling method, and become two soil filling procedures, that is, galvanized soil filling. Zinc filling soil and plastic filling soil are coated on the surface of the steel plate by using the characteristics of high density and stability of galvanized filling soil so that the joint is denser, and there will be no foaming phenomenon like traditional soil filling at high temperature. In addition, whether it is galvanized soil filling or the subsequent plastic filling soil, a hardener is required to make the soil filling dry.
When the galvanized soil filling is completed and roughly leveled by the scraper, wait for about 10-20 minutes, the soil filling will dry, and then it will be polished with sandpaper. Grinding is divided into dry grinding and wet grinding.
Wet grinding is smoother than dry grinding, but it is more labor-intensive. The current practice is to use dry grinding for large areas and wet grinding for small areas and details. Sanding with sandpaper can make the particles on the surface of the galvanized soil smoother first, then make the capillary pores on the surface of the galvanized soil smaller, and finally make the surface smoother, which can match other sheet metals. cut flat. Usually, there are two grinding steps.
- Dry grinding: Use the pneumatic turntable to connect the sandpaper for grinding.
- Wet grinding: It is to stick water sandpaper with a grinding board, and the technicians use manual grinding and watering with a water pipe.
Step 3: Plastic fill soil
It is not enough to use galvanized soil to fill the soil. It is also necessary to use plastic soil filling mixed with hardener to cover the galvanized soil to level it. Because the surface of plastic soil filling is more delicate and smoother, it is easier for the primer to adhere to it. So, this step must not be omitted. After filling the soil with plastic, it is also sanded with water sandpaper to make the surface smooth and smooth, and it is the same as the height of the sheet metal.
Step 4: Middle coat primer
Primer (also known as a secondary primer) is an extremely important step in the paint baking process. If the primer is not used, the surface paint can be sprayed directly on the surface of the plastic filling. Since the density of the plastic filling is not as good as other undamaged ones, the surface paint that has been polished with sandpaper will still have fine pores on the surface of the plastic filling. , so if the surface paint is sprayed directly on the plastic filling soil, it will happen in the plastic filling part, the paint will be absorbed, but the old surface paint will not absorb the new paint, so it will make the whole car paint The surface height and density are inconsistent, and the body coating becomes a strange situation of dog skin plasters. Therefore, the primer is required. In addition, the primer has high hardness and high density, and it can be regarded as a coating material that can isolate air, and moisture and prevent rust.
Theoretically, the whole car should be coated with the primer, but because the density of the primer is quite high, it is not easy to dry. It usually takes 12-15 hours to dry completely after spraying.
Step 5: Spray Topcoat and Gold Oil
Before spraying the surface paint, mix the surface paint and the special banana water for baking paint in a ratio of 2 to 1. After mixing, pour it into the special spray gun for baking paint. The whole step needs to be sprayed three times, and the first time is sprayed. Wait for 5 minutes Spray the second time, wait 5 minutes after the second spray, and then spray the third time. After spraying, it should be heated at about 60 degrees in the paint room. At present, this kind of low-temperature baking paint at about 60 degrees to 70 degrees is generally called cold baking paint. There is no way for cold-baking paint to make the paint harder. It just makes the paint dry faster. The time and temperature of cold-baking are different from each other. There are two stages and three stages.
The purpose of the paint baking room is mainly to be dust-free. The fan is used to draw in the air, and it blows down through the air filter cotton above. With the ventilation of the floor, it creates a downdraft, so that the dust does not fly up, and the filter cotton filters out large particles. Part of the dust is how the dust-free paint room is different from the traditional spray painting. Dust-free is the first, and quick drying is the second. Of course, it is best to leave it in the dust-free paint room for a whole day, or even 2-3 days. Let the paint surface dry naturally. But time doesn't allow so it needs to be heated.
In the past, the paints were only plain colors and silver powder pearls. With the progress of the times, the current coatings are divided into plain colors, silver powder pearls, crystal pearls, high-color paints, etc., and the relative construction difficulty will also increase. If you choose plain paint, the paint already contains gold oil, and you don't need additional gold oil to give off a good luster. But if it is silver powder paint or pearl paint, you need to spray another coat of gold oil.
Step 6: Closing
After the gold oil is dry, if there are still particles on the surface of the car body, then it is necessary to use coarse wax or 1500-2000 water sandpaper to grind and polish, and the car body surface is smooth.