Car paint spraying method
The overlapping spray method is mainly suitable for spraying middle paint and various top coats. This method can improve the painting efficiency and shorten the construction cycle.
1. intermediate paint spraying method喷涂。 Middle paints such as alkyd (including ester glue, phenolic) two primers, thick-coat amino baking middle paint, acrylic polyurethane middle paint, etc., are more suitable for by spraying.
For example, when spraying two primers such as alkyd, ester glue, dilute aldehyde, etc., since these types of paints are mainly used as intermediate paints for ordinary passenger cars and trucks, domestic large spray guns can be used for spraying. First spray the surface of the object one time, at intervals of about 10-15 minutes (make the solvent in the wet film volatilize and level the paint film), and then spray it once along the surface of the object. 是将腻子表面的砂痕、细小麻眼等毛病填平，故喷涂时后枪可压前枪漆膜面积的二分之一或五分之三的面积，以便将毛病喷平。 The pressure gun during spraying should be flexibly controlled according to the actual situation of the surface. For example, the putty coating part, because the of painting in the spray is to fill the sand marks on the surface of the putty, small pits and other defects, so the rear gun You can press one-half or three-fifths the area of the paint film of the front gun to smooth the fault. For the base layer without putty layer, the rear gun can only press one-third or two-fifths of the area of the front gun when spraying. Do not press the gun too much to prevent dripping or sagging on the vertical surface (elevation).
When spraying amino-drying mid-coating, most of the amino-drying mid-coatings have the characteristics of thick coating and are not easy to be filled. Therefore, the area of the pressure gun can be appropriately increased to fully cover the small defects on the bottom surface. However, it should be noted that the paint in amino drying is not easy to dry at normal temperature and the leveling time of the paint film is long, so the distance between the spray gun and the surface of the sprayed object should not be too close when spraying.
In order to prevent the paint film from falling too much (fingers). But for horizontal objects, this problem does not exist.
When spraying high-grade or imported intermediate paints such as acrylic polyurethane, these paints are faster than ordinary intermediate paints such as alkyds. When spraying, you must master the moving speed of the spray gun (not too fast) to prevent paint film. Too thin leads to poor coverage and leveling, and it is necessary to master the spraying interval and the number of pressure guns to ensure the spraying quality of high-grade intermediate paint.
的最后涂层和外观涂层。 2. Topcoat spraying method <br /> The topcoat includes various topcoats and finishing varnishes. It is
Before spraying various topcoats, first, thoroughly clean the spray gun and other tools with thin materials; second, test spray (test gun) before each spray. After the test spray is correct, spray it formally to prevent rough branches and large leaves. Cause rework.
，当压力达到0.5-0.6MPa时，扣动喷枪的扳机，使稀料强力喷出，将喷枪的里面彻底冲洗干净。 When cleaning the spray gun, you can first inject this kind of thin material (matched with the type of topcoat) into the gun can 0.3 ~ 0.5kg. Tighten the can, connect the air hose, and start the , when the pressure reaches 0.5-0.6MPa At that time, the trigger of the spray gun was pulled to make the thin material spray out forcefully, and the inside of the spray gun was thoroughly washed away.
When testing the gun before spraying the topcoat, such as spraying the body surface (elevation) of large and medium-sized passenger cars, first turn the knob on the head of the spray gun (take the gun imported from Japan as an example) to the horizontal state so that it sprays evenly. Fan-shaped paint mist, and the thickness of the paint film is uniform, and the gloss is consistent, and then formally spray; when spraying various cars, because the car is small in size and there are many flat parts, the knob can be turned to a vertical shape to make it spray out horizontal fan-shaped paint mist Moreover, the paint film formed by the paint mist is even and flat, and there are no impurities and other bad phenomena, and then spraying is officially performed; when spraying narrow and small shaped areas (such as small narrow columns, edges, round holes, etc.), the debugging bolt of the spray gun can be Tighten it to spray a circular paint mist to form a circular coating film. However, the spray mist of this paint mist is very sufficient when spraying, and the spraying interval should be controlled to be 300 ~ 400mm away to prevent flow paint.
1) Passenger car topcoat spraying method When spraying ordinary passenger car topcoats, because these types of cars often use alkyd magnetic paint (including full-gloss, semi-gloss, and non-gloss magnetic paint) as the topcoat, spraying should usually be divided into two times.
In order to make the top coat dry in time, the first coat can be sprayed by vertical spraying. This will not only make the paint film thin and dry quickly, but also help to fill the small hemp eyes and orange pits on the surface of the grass. Flat to lay the foundation for the second finish, which is convenient for improving the quality of the second finish. When spraying the second top coat, the overlap spray method (ie, wet-to-wet spray method) is used to make the paint film plump and flat.
When spraying the second topcoat, such as spraying all-light alkyd magnetic paint, the paint contains more resin components, the pigment content is moderate, and the paint film has better leveling. Therefore, the spray gun must always be on the surface of the object to be sprayed when spraying. Be horizontal, do not tilt, and do not go too far or too close. 倾斜时（喷涂角度不正确），喷后的漆膜易产生上薄下厚或上厚下薄现象。 tilted (the spray angle is incorrect), the paint film after spraying tends to be thinner or thicker. If the spraying interval is too close, the paint film is easy to drip and sag; if the spacing is too far, the paint film is thin, the gloss is low, or the surface is rough (fog particles caused by the formation of a flat paint film).
When spraying a semi-gloss or matte alkyd topcoat, because this type of paint contains more pigments, especially physical pigments, the paint film has poor leveling and the surface dries quickly. Therefore, the speed of the spray gun should be appropriately slower when overlapping spraying. The spraying distance should also be moderate. Because in the topcoat spraying, there is no fixed data on the moving speed and spacing of the spraying, all rely on field operations. It should be mastered flexibly according to the drying performance of the paint type, the size of the spraying air pressure, and the shape of the surface of the sprayed object, and explore the best spraying effect from it.
For the topcoat spraying of middle and high-end passenger cars, because the topcoat is mostly acrylic polyurethane or amino polyester drying paint, as long as the base layer is done well before the topcoat is sprayed (that is, the middle coat is sprayed flat, hemp eyes can be found Net), usually sprayed in one shot with overlapping spraying method, without spraying twice, in order to save the topcoat and improve work efficiency.
The topcoat spraying of high-end luxury buses must be sprayed in two or three times to ensure that the paint film meets the quality requirements of good fullness, smoothness and high gloss. That is, in the first spraying, the overlapping spraying method is used; in the second spraying, the vertical spraying method is used to make the paint film thin and uniform, so as to find the faults; in the third spraying, the overlapping method is used to double spray. (Wet touch wet), but this spraying should be carefully and meticulously to make the paint film full after spraying. Flat and smooth, high gloss (more than 90%), there must be no dripping, sagging, impurities, leaky guns, exposed bottom, thick orange grains and other bad phenomena, especially the external surfaces of the body of high-end luxury buses must meet the above quality, Otherwise, it should be reworked and sprayed again. In order to ensure the quality of the topcoat of high-end luxury buses (including middle-to-high-end cars), first, sprayers must have excellent spraying technology; second, spray guns must use high-quality spray guns; third, the spraying environment must be clean and hygienic, such as indoor spraying and better lighting , Ventilation and working racks (lifting tables, etc.) and other facilities should be complete, when spraying outdoors, you should choose dry and windless weather to prevent rework due to poor operating environment. In addition, it is best for two people to spray at the same time, that is, each person is responsible for one side of the body; when spraying, spray the inside of the car and the inside of each bin first, and then from top to bottom, left to right Spray all sides well, the pressure gun when spraying should be even and tidy to make the paint film straight and beautiful after spraying, and no bending phenomenon should occur, so as to prevent uneven paint film thickness. When spraying in sections, the overlap should be sprayed flat to prevent joint marks.
2) Automobile topcoat spraying method. Spraying the car topcoat, because the car is small in size, small in area, and low in body, correspondingly sprays better than high-end luxury passenger cars.
However, due to the different shapes of various cars, such as the shapes of Japanese Toyota and Honda, they have more large curved areas. Therefore, when spraying, be sure to spray out the quality of the topcoat of the curved parts so that The paint film has good fullness, is smooth, and the gloss can clearly reflect the figure. For various cars with small curved areas and small surfaces, the main point is to spray the plane well, while taking into account the quality of the façade and the side surface to make it close to the quality of the paint film on the plane, so as to display the appearance of the car.