Automobile bumper generally can be divided into metal bumper and glass-reinforced steel bumper two kinds, its coating technology is different.

(1) Coating of metal bumpers

Dip with cotton cloth and so on to remove oil stains, with 60~70 abrasive cloth to remove rust, with compressed air, towels and other clean floating dust.

Spray a primer with a viscosity of 22-26s H06-2 iron red epoxy primer or C06-l iron red alcohol primer. Bake the primer LH at 120℃ for 24h. The thickness is 25-30um. Scrape putty with ash alkyd putty, bake at 24h or 100℃ for l.5h, then grind with 240~280 water sandpaper until smooth, wash and dry. Spray the first finish with 18~22s viscosity black alkyd magnet paint, dry at room temperature for 24h or l00℃ for lh, then gently polish the surface of the film with 280-320 number of water sandpaper, scrub it clean and dry. Spray the second topcoat and dry for 40~60min at 80-100℃ for 24h.The requirement for coating film is the same as that of girder.

The procedure of metal bumper painting is as follows.

 1) Basic treatment: First remove the oil with cotton yarn fungus gasoline, then remove the rust with 60~70 emery cloth, blow with compressed air or clean the floating ash with a brush.

2)  Spraying head primer: Dilute H06-2 iron red epoxy ester primer or C06-1 iron red alkyd primer to a viscosity of 22~26s, and evenly spray the inside and outside of the bumper. The paint film should be 25~30um thick after drying.

3) Drying: 24h self-drying at normal temperature, or epoxy ester primer at 120℃ drying lh, alkyd primer at 100℃ drying lh.

4) Scraping putty; With grey alkyd putty, scrape and smooth the uneven place, the thickness of the putty layer is appropriate to 0.5-1mm.

5) Drying: self-drying at room temperature for 24h or drying at 100℃ for 5h.

6) Water mill; With 240~280 water sandpaper, the putty part water grinding smooth, wipe, dry or low temperature drying.

7) Spray the first top coat: Dilute the black alkyd enamel to a viscosity of l8-22s, filter and clean, and evenly spray one coat.

8) Drying: self-drying at room temperature for 24h or drying at 100℃

9) Water grinding: with 80~320 water sandpaper, the putty part water grinding smooth, wipe, dry or low temperature drying.

10) Spray the second coat: dilute the black alkyd enamel to a viscosity of 18~22s, and evenly spray the front and secondary surfaces together. After spraying, the film should be smooth and bright, and there should be no defects such as leakage, wrinkling, bubbling, flowing, paint accumulation and impurities.

11) Drying: self-drying for 24h or 40-60min at 80-100℃. To paint the metal bumper, in order to obtain a plump bright, hard and strong adhesion film, it is best to paint the amino drying paint, in order to improve the quality of the film; For metal bumpers in urgent need of assembly, in order to shorten the construction period and improve the production efficiency, nitro enamel coating can be used. When spraying the top coat, 2-3 lines can be continuously sprayed, and lh can be assembled and used after spraying.

(2) Coating of FRP Bumper

 1) Dewaxing: FRP bumper in the product defilm, the surface often has a layer of wax. If the wax is not removed thoroughly, it will seriously affect the adhesion of the coating, so that the coating film will be delamination when it encounters a hard collision (falling). Therefore, wax must be thoroughly removed to ensure the quality of paint. There are two methods for dewaxing: hot water washing and solvent washing. When using hot water for dewaxing, soak the workpiece in hot water at 80-90℃ for 3-5 min. After the wax is melted and washed, the wax can be removed by immersing it in 60-70℃ hot water for 2 to 3min. When organic solvent is used for dewaxing, the workpiece surface can be ground with No. 60~70 emery cloth, and then the wax can be repeatedly washed with xylene or banana water.

2) Scraping putty: Use pervinyl chloride putty or alkyd putty to scrape the uneven place flat. Due to the faster drying, the pervinyl chloride putty can be continuously scraped and coated until smooth.

3) Drying: dry pervinyl chloride putty for 4~6h, alkyd putty for 24h.

4) Water grinding: with 260~300 water sandpaper, the greasy layer after repeated water grinding smooth wipe, dry or low temperature drying.

5) Spray primer: use C06-10 grey alkyd two-channel primer (two-channel slurry) to stir thoroughly and evenly first, and then add xylene to dilute it to a viscosity of 22~26s, and evenly spray the face surface. The thickness of the paint film during spraying shall be determined by fully filling the sand marks.

6) Drying: self-drying 12h or 70~80℃ dry lh.

7) Scraping delicate: Use vinyl chloride putty or nitro putty and add a small amount of diluent to blend into dilute putty. Quickly scratch and smooth the pinhole and other small defects. Like a hard shave. Continuous scraping and coating 2~3 times.

8) Drying: Dry nitro putty for 1-2h and pervinyl chloride putty for 3-4h.

9) Water grinding: the putty parts with 280-320 water sandpaper water grinding, and then with 360 water sandpaper, the putty parts and the face of all paint film comprehensive water grinding smooth, repeated wipe, dry or low temperature drying.

10) Spray the first topcoat:

Dilute perchloroethylene or alkyd magnet paint (black or gray) to 18~22s viscosity, spray the inside and outside of the workpiece thinly and evenly.

11) Drying:

Perchloroethylene paint drying 4~6 hours, alkyd paint drying 18-24 hours.

12) Water mill:

With the old No. 360 or No. 40 water sandpaper, the face-to-face paint film will be water-grinding smooth, scrubbing, drying.

13) Spray a second topcoat:

Perchloroethylene magnet paint to viscosity of 16-18s, alkyd magnet paint to viscosity of 26~30s, the bumper inside and outside all evenly spray together, when spraying should pay attention to the matching paint.If the first varnish is perchloroethylene, the varnish can be sprayed with either vinyl chloride or alkyd varnish. If the first varnish is alkyd varnish, the varnish can only be sprayed with alkyd varnish, not vinyl chloride varnish.

(14) Drying:

Perchloroethylene paint drying 8-12 hours, alkyd paint drying 48 hours.

15) Inspection:

The paint film should be smooth, glossy, good adhesion, no foaming, full, flow hanging, uneven light release, wrinkles, impurities and other defects.Secondary paint film should be smooth and bright, strong adhesion, no obvious flow, flow hanging, impurities and other defects.

How to spend less when you have to repaint bumpers

Generally speaking, when the front bumper of a car is scratched black, it means that the scratch is more serious has damaged the paint, and if this case is to be dealt with, it has to be repainted.It is also necessary to decide whether the paint needs to be repainted or not. For example, if the scope of the paint is small, it is still not necessary to spray paint, but only to carry out the corresponding patching operation to solve the problem.Here’s how we’re going to work, so we can spend the least money to solve the problem of scratching paint.

1. Needed tools: sandpaper, sponge, mending, squeegee, paint spray, all-purpose tape, inspection process: When the bumper is found out in time, get out of the car to check the exact location and then carry out the repair plan.For example, what kind of sandpaper do you want to sand, the layer that needs to be sanded, and the uniformity that needs to be spray-painted? Step

        2. Wash the damaged wound for the next step.The amount of time needed in this process is determined by the degree of trauma and is also related to the way you sharpen it.

        3. Clean up again: This cleaning is also to remove impurities from the grinding process, better next step, mud filling process: during the grinding process, the drug supplementation, preferably to apply evenly, not too thick but beyond the wound position.This process is also to flatten the concave surface and then wait for more than two hours for the mud to dry;

      4 . Continue polishing: This polishing is using 600 number of sandpaper, but also to give the front of the mud poor butt.Until the wound is smooth on other paint, otherwise spray paint will be very poor.This process takes less than 10 minutes to clean up again: this cleaning is also to remove the remaining impurities in the first few steps, this time simply wash clean and wait for drying;

      5.Use of adhesive tape: to prepare for the next step in spraying paint, and to prevent contamination of other complete paint surfaces.Spray painting process: When this project can be counted as almost over, the bumper paint must be sprayed evenly, preferably without color difference.Finally, wait for the paint to dry before using wax for polishing.