2 1 century is called the new century facing the environment. Reducing painting pollution, reducing painting cost and improving painting quality has always been the theme of painting technology development. The following is my paper on automobile painting technology, I hope you can get some insights from it!

Talking about Automobile Painting Technology —— Modern Automobile Painting Technology

Abstract: 2 1 century is called the new century facing the environment. Reducing painting pollution, reducing painting cost and improving painting quality has always been the theme of painting technology development. This paper expounds the common sense of automobile painting technology, probes into the standard technological process of automobile painting, and puts forward some matters needing attention in the process of automobile painting.

Keywords: automobile; Painting; Principle; Technology; Atomic ash

1 automobile painting technology

1. 1 car painting function

(1) protection. Due to the special living environment of automobiles, such as wind, sun, rain and rocks, automobiles are required to have certain anti-corrosion performance and service life. (2) Its ending function Because cars are constantly shuttling between highways and urban and rural areas, people hope that it can bring colorful dribs and drabs to life, and hope that cars are beautiful, comfortable and attractive in color. Therefore, modern large-scale intensive production of automobile painting is necessary, and a lot of manpower and material resources need to be invested to build and manage modern large-scale painting production lines.

1.2 common coatings for automobile painting

(1) According to different coating objects, automobile coatings can be divided into: ① original coatings for new cars; ② Automotive refinishing paints (2) are classified from bottom to top according to the coating on automobiles: ① Primers for automobiles, mostly electrophoretic paints; ② Intermediate coatings for automobiles; ③ Automobile primer (including solid primer and metallic flash primer); (4) car topcoat, generally refers to the solid color topcoat, without finishing; ⑤ car finish varnish; ⑥ car repair paint; (3) Classification by painting methods: ① Electrophoretic paint for automobiles; ② Liquid coatings for automobiles; ③ Powder coatings for automobiles; ④ Special coatings for automobiles, such as PVC sealing coatings; ⑤ Post-treatment materials (antirust wax, protective wax, etc.). ); (4) According to the parts used in the automobile, it can be divided into: ① body paint; (2) cargo compartment coating; ③ Anticorrosive coating of wheels, frames and other parts; ④ Coating of engine parts; ⑤ Chassis painting; ⑥ Paint for interior decoration.

1.3 basic principles of automobile painting and painting

(1) Check tools and working environment before painting. The water and oil in the air compressor must be released first. Thoroughly clean and inspect the spray booth and ventilation screen. Clean the floor of the spray booth.

(2) the surface is clean. After spraying, the surface must be washed with water, free of oil and wax, and the newly welded or rusted metal surface should be coated with epoxy antirust primer to prevent rusting.

(3) the correct grinding method. Don't use too hard sandpaper, try to use thinner sandpaper.

(4) Use high-quality thinner. Don't make an economic calculation of thinner. Only with matching thinner can the paint achieve the highest quality. Using cheap thinner can save several dollars, but it will take more time and energy. Using high-quality thinner will make the work more convenient.

(5) Hardener and diluent. The correct proportion of hardener and thinner will affect the effect of paint.

2 Standard process flow of automotive paint

(1) Body rust prevention and internal painting: It is completed by the sheet metal worker according to the body condition. (2) Polishing and trimming the bevel edge: Use P60~ 180# sandpaper to polish the parts of the car body that need putty after being repaired by sheet metal. (3) Dust removal and cleaning: use pressure gun and desilication cleaner to remove dust and stains on the car body. (4) Sticking: Sticking textured paper with reverse sticking technology. (5) Priming: mix 4: 1 red primer, spray 1~2 layer to expose metal, and then dry. (6) Filling putty: Fill the concave position on the car body with mixed multifunctional putty and leave it at 20 degrees Celsius for 30 minutes. (7) Polishing putty: Polishing putty with P60~240# sandpaper, and checking flatness, pinholes and traces with hand feeling or polishing indicator layer. (8) Extra-young putty: choose it when necessary to fill pinholes, sandpaper marks, etc. (9) Polishing: Use P280# sandpaper to thoroughly polish the old paint that needs to be sprayed with intermediate paint. (10) Dust removal and cleaning: use pressure gun and desiliconization cleaner to remove dust and stains on the car body. (1 1) Sticking: Sticking masking paper. (12) Spraying intermediate paint: mix 2~3 layers of multifunctional intermediate paint, with an interval of 5~ 10 minute for each layer, then dry at 60 degrees Celsius for 30 minutes, and then spray the polishing indicator layer. (13) Polishing intermediate paint: polish the dried intermediate paint with P320~400# sandpaper. (14) Inspection: Check the grinding effect and carry out micro-filling. (15) Dust removal and cleaning: remove dust and stains from the car body. (16) Paste: Paste the shielded car body. (17) Dust removal and cleaning: firstly, blow out the dust spots on the car body with a pressure gun, remove the stains on the car body with a desilication cleaner, blow out the dust in the gaps of the car body with a pressure gun, and finally remove the dust on the car body with a sticky dust cloth. (18) plain paint spraying on top coat: spray 2-3 layers, with the interval of 5-10 minute for each layer, and add curing agent and diluent according to the temperature. (19) Primer spraying: spray 2-3 layers of plain paint, silver powder paint or pearlescent paint with an interval of 5- 10 minute. (20) Spray painting: mix and spray two layers of varnish every 5- 10 minute, and add curing agent and diluent according to the temperature. (2 1) drying: let stand for 5~ 10 minutes and dry at 60℃ for 30 minutes. (22) Waxing and polishing. (23) build a car. The purpose of building a car is to prevent the spray from spraying where it should not be sprayed. The traditional basic covering materials are covering paper and covering tape. The width of automobile cover paper ranges from 7 cm to 9 1 cm, which is heat resistant. Generally, it can be used safely in the drying room, with good wet strength, which can prevent solvent penetration (note: newspapers cannot be covered with newspapers, which are not heat-resistant and contain printing ink, which will dissolve in the paint solvent and penetrate into the topcoat below, causing pollution). 3 matters needing attention in the process of automobile painting

(1) Repair before painting. For defects such as local corrosion and slight hard damage of body parts, if they are dug out and leveled, it will not be worth the loss. If it is directly filled with putty without repair, the strength and corrosion resistance are poor. Repair before painting aims at effectively making up for such defects. The common repair methods are: soft metal filling and soft metal filling (commonly known as hanging tin) to repair the surface defects of parts, which have the advantages of good adhesion, simple process and strong impact resistance. The aluminum foil is filled with resin plate, and the aluminum foil is pre-coated with synthetic resin, which contains a certain proportion of metal powder, which improves the strength and is convenient and quick.

(2) Sandpaper grinding. Hand-grinding plane should be carried out with sandpaper pad on the hand template, and a large area should be replaced with larger grinding pieces, which not only saves labor but also improves the grinding quality of sand grinding. When grinding narrow edges and corners, smaller grinding blocks should be used, and when grinding contours or arcs, copying grinding blocks with similar shapes should be used. When there is no grinding block but sandpaper, painters usually put sandpaper between thumb and palm, and put their hands flat on the surface. Manual grinding should be uniform, not too hard for quick success and instant benefit, and the operation direction of manual grinding should also alternate. Otherwise, it is easy to grind out the depression, so that the previous efforts are in vain.

(3) deoiling for the second time. Although the car body surface has been cleaned, painted, derusted and repaired, the dirt left after sheet metal repair, oil stains on tools and oil stains on the parts where the old paint has not been removed will definitely affect the air adhesion, and even peeling or orange peel will occur after the top paint is sprayed. So be sure to remove the oil before painting. It is best to use a wax remover and wipe the surface to be painted with a clean dry cloth.

Four problems that should be paid attention to in automobile cleaning

(1) Special car wash liquid should be used, and soap or detergent is strictly prohibited, because such products are highly alkaline, which will lead to the loss of luster of paint surface, local color difference, aging of sealing rubber and accelerated metal corrosion of paint surface falling off. (2) Before high-pressure flushing, check whether the windows and front and rear covers are closed. (3) During high-pressure flushing, the water pressure should not be too high, generally not higher than 7Mpa. First, wash the whole vehicle with dispersed mist water flow, and then wash it with concentrated water flow after infiltration. For the cleaning machine with adjustable pressure, the water pressure can be higher when cleaning the chassis, so that the sludge and other attachments attached to the chassis can be washed away. When cleaning the car body, the water pressure can be reduced. If the water pressure and water flow for cleaning the car body are too large, dirt particles will scratch the paint layer. (4) Use a temperature regulating cleaning machine, and pay attention to the fact that the temperature of hot water cannot be too high, so as not to damage the paint layer. (5) When wiping the cleaning agent, a soft towel or sponge should be used, preferably a sponge, to avoid hard particles scratching the paint surface. (6) Every process of car washing should follow the principle of top-down, that is, from the roof, front and rear covers, side of the car body, lamps, bumpers, skirts and wheels. (7) Don't wash the car in direct sunlight. If the sun shines directly, the water on the car surface will evaporate quickly, and the water droplets on the dry car body will leave spots, which will affect the cleaning effect. (8) Don't wash the car in the cold, in case the water drops freeze on the car body and the paint layer breaks. Indoor car washing in the cold season in the north. After the vehicle enters the station, stop for 5- 10min, and then wash it. (9) If dust or impurities are found on the car body, they should be removed in time to avoid polluting the paint surface.

5 Pay attention to daily maintenance

(1) Before, during and after vehicle use, the dust on the vehicle body should be removed in time to minimize the adsorption of static electricity on the dust on the vehicle body. (2) Clean in time after rain. After the rain, the rain stains on the car body will gradually shrink, so the concentration of acidic substances in the rain will gradually increase. If the rain stains are not washed with clear water as soon as possible, the finish will be damaged over time. (3) When washing the car, it should be carried out after the engine is cooled. Don't clean the vehicle in the scorching sun or high temperature, so as to avoid leaving traces after the detergent dries. Usually, special detergent and neutral tap water should be used to clean the vehicle, and alkaline washing powder, soapy water and detergent should not be used to prevent oil stains from washing off the paint surface and accelerate the aging of the paint surface. (4) Clean and soft cloth or sponge should be used to scrub the vehicle to prevent metal chips and sand particles from being mixed. Do not use a dry cloth, towel or sponge to clean the vehicle to avoid scratches. When wiping, you should wipe it gently from top to bottom along the direction of water flow, instead of drawing a circle, wipe it horizontally. (5) Some special traces with strong corrosiveness (such as asphalt, bird droppings, insects, etc.). ) should be removed in time. In this regard, it must be cleaned with a special cleaner. Do not scrape with a blade or remove with gasoline to avoid damaging the paint surface.

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