Decrypt the car bumper spraying production line process!
We all know that in the process of driving a car, the car bumper can be said to be the first guardian line of our lives, in the event of an accidental collision can effectively reduce the damage to the outside world. So, how does the car bumper ensure that it will not rust and corrode in a harsh environment, thus affecting the quality of the bumper? This is related to the process flow of the car bumper spraying production line. Next, I will take everyone into the scene of the car bumper spraying production line, and see how the bumper is sprayed!
Automobile bumper spraying production line process:
Work on the workpiece → pre-treatment (pre-degreasing → degreasing → washing 1 → washing 2 → pure water washing → blowing water) → moisture drying → cooling → turning → wiping, grinding → flame treatment → electrostatic dust removal → spray primer → leveling → Spray paint → leveling → spray varnish → leveling → solidification drying → inspection, polishing, inspection → workpiece off-line.
Pre-treatment is directly related to the quality of the bumper spray. On the one hand, the pretreatment can improve the anticorrosion performance of the coating film and prolong the service life of the workpiece, on the other hand, the adhesion of the coating film to the substrate can be improved, and the bumper coating film can have uniform performance.
(2) moisture drying
The purpose of moisture drying is to fully dehydrate the surface of the pre-treated bumper to obtain a substrate for surface spraying operations. However, the drying temperature should not be too high, as excessive dewatering can result in a significant drop in coating performance.
(3) Surface spraying
Usually, the bumper surface coating consists of multiple coating films with different functions. Wet spray wet spraying is now used, which can save energy, simplify the process, and adapt to the needs of large-scale assembly line production.
At present, the more advanced coating line consists of painting robot, two-component paint supply, automatic color change, workpiece recognition, synchronization, total control and other subsystems, with automatic color change, automatic recognition, synchronous motion, offline simulation and other functions. Multiple robots move in sequence, and complete the processes of polishing, flame treatment, electrostatic dust removal, primer, topcoat and varnish painting. Of course, the full operation of the robot is fully automated, and the investment and operating costs are relatively large; it is currently not used in most domestic manufacturers.
(4) Polishing and wiping
After the bumper is pre-treated, it enters the next polishing process. This process can be determined according to the actual situation of the surface of the workpiece, but it must pass through this process when the surface of the workpiece is uneven or has other damage.
(5) Flame treatment
The flame treatment uses a high temperature (3000℃ or higher) gas flame to oxidize the surface of the plastic. Surface tension or surface energy is generally used to measure the ability of a substrate to adsorb liquid. If the surface energy of the substrate is at a high level, the liquid will become more wet on the surface and have good ductility. The basis of the liquid. Flame treatment can increase the surface tension of the substrate, making the bonding strength between the substrate and the coating more versatile and easier to spray.
Flame treatment involves a complex series of physical and chemical reactions. On the one hand, the high-temperature flame transfers energy to the oil and impurities attached to the surface of the substrate, causing it to evaporate by heat, which serves to clean the surface of the substrate. On the other hand, the flame contains a large amount of ions with strong oxidizing properties. These ions react with the surface of the treated object at a high temperature to form a charged polar functional group on the surface of the treated object, thereby improving the substrate. The surface energy, which in turn increases its ability to adsorb liquids.
Maintaining a certain flame temperature and distance, the pre-spraying treatment of the workpiece surface at an appropriate moving speed can reduce the surface stress of the workpiece, improve the adhesion of the surface of the workpiece, and improve the quality of the coating.
(6) Electrostatic dust removal
The burr of the workpiece surface due to electrostatic adsorption can be removed to ensure the cleanliness of the workpiece before spraying, which is beneficial to improve the coating yield. The main equipment can use electrostatic precipitator, electrostatic precipitator, electrostatic precipitator, dust collector and so on.
The purpose of the primer is to improve the penetration resistance of the coating, enhance the protection of the substrate, mask the fine defects on the surface of the substrate, enhance the adhesion of the topcoat to the surface of the workpiece, and ensure the uniformity of the color of the topcoat. The thickness of the primer layer is usually 5 to 8 μm.
(8) After applying the primer bumper, the primer is applied and the primer is applied after leveling.
Topcoating, this is a critical stage in the completion of the coating process. The corner of the topcoat is to provide the required decorative color, to achieve the design requirements, and to protect the workpiece from atmospheric, acid rain, to prevent UV light penetration, and greatly increase the anti-aging ability of the substrate. The top coat is typically 30 to 35 μm thick in multilayer coatings.
The function of the varnish is to enhance the external corrosion resistance of the topcoat, protect the topcoat from oxidation, and increase the metallic luster of the finish to make the appearance of the product more vivid. The thickness of the lacquer layer is usually 10 to 15 μm.
(10) leveling and drying
The leveling and drying process is a process in which the solvent or moisture in the coating evaporates, so that the coating film can be touched or re-sprayed. The leveling effect depends on the volatilization speed of the diluent. The quick-drying thinner can slow down the movement and flow of the paint film, resulting in defects such as orange peel, dry spray and poor wetness of the film; slow dry diluent remains in the wet film. The longer time inside can make the paint film smooth, but it will cause sag, spot and color inconsistency. Therefore, the leveling effect should be observed at any time, and the solvent evaporation rate should be controlled to ensure that the paint film leveling area must be kept clean and dust-free.
(11) baking curing
After the sprayed bumper is leveled, it needs to enter the curing oven for curing. The baking curing of the coating is a melting and chemical reaction process, which makes the coating film hard and friction resistant, and is an important part of the coating process. The baking time and temperature will determine the properties and characteristics of the coating. Insufficient baking can result in uneven coating thickness, poor adhesion, poor weatherability, and reduced strength and hardness. Excessive baking can result in eclipse of the coating. The coating film is coked and the mechanical strength is seriously degraded.
(12) Workpiece transportation
According to the existing engineering examples and the requirements of most users, the general front and rear treatments are carried by the sliding ground chain, and the double-station is placed on the sliding raft for continuous operation. There are also pre-treatments in the form of hanging and post-processing using the ground chain.
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