New technology for automobile painting construction----Putty scraping method for whole vehicle

In automobile painting, there are often many unevenness such as convex and concave hammer marks on some passenger car shells or car shells that are knocked by hand. It is necessary to scrape putty all over the car to improve the flatness of the base. Therefore, for the construction of putty on the whole vehicle, the putty type with better scraping property should be selected first, so as to be suitable for the construction of scraping. For example, the shell of a large and medium-sized passenger car can be scraped with cooked tung oil and other oily putty (self-drying putty); while for the shell of a car, in order to improve the coating quality, it is necessary to scrape with putty . However, since the putty dries quickly, in order not to affect the scraping application, the amount of curing agent can be appropriately reduced during the preparation , so as to slow down the dryness of the putty after adjustment, so as to facilitate the scraping application.

1. Scratch coating method of oily putty on the whole vehicle

Take the scraping of medium-sized passenger cars (minibuses) as an example. Use the prepared oily putty, and use a steel sheet or copper sheet wide scraper to scrape the front and rear areas of the outside of the completely, and then scrape the unevenness on the surface of the door and the upper roof with the large bread boards on both sides . Use a wide scraper to scrape and level the places in turn. After each place is fully scraped and leveled, the residues on the scratches and edges should be collected in time. When scraping again, according to the flatness of the base layer, it can be scraped from top to bottom, or from left to right. Such as the front and rear parts, it can be scraped from left to right; the large board surface can be scraped from front to back or from top to bottom. For the parts with obvious convex and concave parts, it can be scraped continuously for 2~3 times until the scraping is smooth. Each scraping can be done back and forth 1~3 times. The thickness should be 1~3 mm, not too thick to prevent putty after drying cracking. After these parts are smoothed, the uneven parts around the window frame, around the door, and around the front and rear windshield frames are finely scraped and leveled in turn. Generally speaking, 4-5 coats of putty are required for the whole vehicle to achieve smoothness. Generally, coarse putty is used for the first two coats to facilitate timely drying; finer putty is used for the last two or three coats to improve the smoothness of the putty layer.

However, it should be noted that the first two coats of thick putty should not be reciprocated too many times during scraping to prevent the oil from squeezing out the closed surface and affecting drying. Another point is that after each scrape is leveled, the scratches on the surface should be gently flattened, and the residues on the edges and other places should be cleaned up, and no obvious lap marks can be left at the overlapping joints of the segmented scraping. As long as you pay attention to these essentials, the quality of putty scraping is guaranteed.

2. Scratch coating method of atomic ash on the whole vehicle

Take the case of scraping the shell of an ordinary car. For the scraping of the putty on the car shell, it is necessary to use a steel scraper and a rubber scraper to scrape, so as to obtain a relatively smooth scraping quality. For example, the flat parts such as the engine cover, roof, door and rear wall of the car can be scraped and leveled with putty in turn with a steel sheet or copper sheet wide scraper. For surfaces with round or elliptical shapes, such as around the door, around the upper roof, around the front and rear windshields, etc., it is recommended to use a rubber scraper to scrape and smooth. For example, when using a steel scraper to scrape the round part, it is easy to leave more scratches, which will affect the flatness and the progress of polishing.

When scraping putty on a full car, the scraping speed should be faster than that of oily putty, and each place can only be scraped 1-2 back and forth quickly, and it is not allowed to scrape back and forth too many times to prevent sand holes or numbness , especially for lap joints, more attention should be paid.

After each side is scraped and leveled, the residue should be collected in time. After the whole vehicle is scraped, an inspection should also be carried out, and the scraped parts should be repaired and smoothed in time. Generally speaking, the putty can be scraped continuously until the scraping is smooth. Because the putty is a curing putty, it can fully dry within a few hours even if it is applied thickly. This is the unique performance of putty compared with other putties .