First, sheet metal correction is the preliminary plastic work of painting. We compare it to the human body. A perfect human body is like a model's figure, which symbolizes luxury fashion. If you let a man with a broken limb wear it, it's nothing, and it will be eclipsed. Then if you let a fashion model wear it, it will look dazzling and noble. Very simple, how can a twisted car body set off the brilliance of paint? Many painters think that sheet metal is not their job, I don't think so.
Second, after the scraping body is corrected by sheet metal, there are still some defects that can't be compensated by sheet metal work. Even if new parts are replaced, there will be imperfections. In order to be more perfect, we need to use sculpture to make up for the defects. After the car is deformed and damaged for other reasons, its flatness, wheel angle and lines need to be scraped and polished. It is clear with this formula, scraping ash = repairing body skin = mold product = mold processing program. Any body skin is stamped with a die. We repair the body skin just like repairing the mold, so our scraping molding process should be consistent with the mold processing, which is impossible for ordinary painters. Many painters who have worked for many years will sigh, "It is easy to spray a car well, but it is difficult to grind it in ten years."
Third, painting is usually divided into three steps.
<1> The first primer fills the sand marks and micropores at the bottom of the workpiece, which increases the adhesion of the lower coating and also has the function of defect indication.
In < 2 >, it is very important to apply primer, so as to prepare a complete and smooth working surface for the topcoat, complete the last procedure of all primer work, increase the adhesion of the intermediate layer and have a certain isolation effect, and ensure the quality stability of the topcoat.
< 3 > topcoat topcoat is divided into single-layer paint and multi-layer paint, which are color fixing layer and decorative protective layer. Single-layer paint is commonly known as plain paint, also known as ordinary paint, and can be completed in one layer. Multi-layer paints are divided into silver powder series paints and pearlescent series paints, which are completed in two-layer and multi-layer construction procedures. Silver powder paint adopts special aluminum material, which has high protection, strong outdoor stability and strong observability. Pearl series paint is made of mica and shells through high technology, which is a kind of high-grade paint with rich colors and strong decoration.
The spraying quality of topcoat is very high. It is not easy to be clean, plump, bright, not sagging, not hanging flowers, uniform luster, not leaking flowers, not flashing flowers, good leveling, not biting, not impetuous, not color cast. It's really not easy to accomplish these things in one go, which requires extremely rich experience and troubleshooting ability.
Four, paint surface treatment, as the name implies, is the last process of topcoat. After the paint surface is dry, there will be defects on it. If we try our best, some imperfections will flow down, and then we can only remedy them later. In fact, the satisfactory paint surface is not perfect. For example, the loading paint of Mercedes-Benz and BMW will have a slight fine fish scale phenomenon, which is also commonly known as orange peel phenomenon. This is a natural phenomenon caused by the drying time difference of paint film during leveling. Of course, it is difficult for ordinary people to detect it, and it needs expert appreciation to find it. Therefore, if we want to fool the eyes of experts, we have to carry out paint treatment, which we call "mirror treatment" First, use 1500-2000 mesh beauty sandpaper for leveling and polishing, and then use coarse wax composed of pumice or clay to polish to remove the traces of sandpaper. Next, polish with fine wax to remove traces of coarse wax, then use reducing agent to achieve perfect luster, and then use mirror treatment agent to completely remove ring lines and scratches. At this time, it can be achieved with paint.
Sheet metal is not that simple.
Many people think that automotive sheet metal painting repair is a simple manual process. In fact, the whole maintenance process requires trained personnel and professional equipment. After the damaged vehicle has been tested and properly maintained, it is time for sheet metal and painting.
In terms of technology, carbon dioxide gas shielded welding is basically used now, which avoids the shortcomings of large heating area of oxygen-acetylene and destroying the internal structure of metal in the past. However, in terms of technology, we should beware of "cutting corners" in individual shops, filling the depressions with putty and not flattening the metal plates. Thick putty, when heated, will cause the paint surface to crack, especially near the front cover of the engine and air conditioner, which has greater hidden danger.
Painting is a meticulous job.
The whole painting process includes more than a dozen processes, and without one, it is impossible to guarantee that the car paint will last as long as new. There are several aspects that are prone to problems. First of all, clean the surface, many roadside shops can't do it, just wipe two casually, and leave all the troubles to customers in the future. Secondly, in the step of spraying primer, the regular repair shop will follow the procedure step by step, but the small shop can save money, so the customer will not notice any difference when picking up the car, and only when it is used later will there be problems such as paint fading. The third is to spray color paint. Master Wang said that the colored paint and bright oil should be sprayed three times each to ensure that the effect after painting is as bright as new. If you cut corners, you will leave many hidden dangers.