Several common surface treatment processes for cars
Views : 597
Author : Connor
Update time : 2022-01-07 17:27:58
Today we would like to introduce you to Jiipower's common surface treatment processes: painting, powder coating, and electrophoresis.
There are two kinds of painting and powder coating (plastic spraying), painting on the car I believe we all know very well, the most common car paint will be sprayed on three layers: primer, paint, clear coat. Luxury cars will be more complex, the paint will also be divided into a variety of such as metal paint, pearl paint, metal paint will be added to the paint magnesium powder and other metal substances, so that the paint luster more like metal, corrosion resistance, scratching ability will also be stronger. Pearlescent paint will add mica particles to the paint, and mica pigments coated with titanium dioxide and iron oxide are added to the paint base. Mica itself also has a special, transparent color. In this way, the reflected light has a kind of pearl-like sparkle. Moreover, the titanium dioxide itself has a yellow color and changes to light blue when you look at it obliquely and has different colors when you look at it from different angles. Therefore, the pearlescent paint gives people a novel, colorful and dazzling feeling.
Plastic spraying is a surface treatment method of spraying plastic powder on the parts. Plastic spraying is also commonly known as electrostatic powder coating, its treatment process is a more common decorative technology used in the international metal surface treatment since the 1980s. The advantages of this technology compared with ordinary spray paint surface treatment are reflected in the advanced technology, energy-saving and efficient, safe and reliable, colorful, and so on. Its working principle is to charge the plastic powder through the high-voltage electrostatic equipment, under the action of the electric field, the coating will be sprayed onto the surface of the workpiece, the powder will be uniformly adsorbed on the surface of the workpiece, forming a powder coating; and powder coating after high-temperature baking and leveling curing, plastic particles will melt into a dense layer of different effects of the final protective coating; firmly attached to the surface of the workpiece. The spraying effect is better than the spraying process in terms of mechanical strength, adhesion, corrosion resistance, aging resistance, etc.
Powder Coating Process
The pretreatment process is one of the most important parts of the powder spraying process, it will directly affect the quality of powder coatings, pretreatment is not goodwill lead to easy peeling off the coating blister. Therefore, we must pay attention to the pretreatment work.
Relative to the plate metal parts can use chemical pretreatment methods: oil removal → rust removal → cleaning → phosphating (or purification), etc.
For product workpieces with thick rust/surface, use mechanical rust removal methods such as sandblasting, shot blasting, etc. After mechanical rust removal, ensure that the surface of the workpiece is clean and free of scale.
Scraping putty: according to the degree of defects on the surface of the product workpiece, use conductive putty to scrape the defects, and smooth them with sandpaper after thorough drying, ready for the next process.
Protection: If some parts on the workpiece do not require coating, they can be covered up before preheating using protective adhesive, etc., to avoid spraying on the coating.
Preheating: Generally, preheating is not required. If a thicker coating is required, the workpiece can be preheated to 100-160°C to increase the thickness of the coating.
2. Powder coating
The workpiece enters the gun position of the powder spraying room through the conveyor chain to prepare for the spraying operation. Electrostatic generator through the gun muzzle electrode needle to the workpiece direction of the space release of high-voltage electrostatic (negative), the high-voltage electrostatic make from.
The mixture of powder and compressed air ejected from the gun muzzle and the air around the electrode is ionized (negatively charged). Workpiece through the hanging tool by conveying link ground (grounding electrode), so that an electric field is formed between the gun and the workpiece powder in the electric field force and compressed air pressure under the dual impetus to reach the surface of the workpiece, relying on electrostatic attraction in the workpiece surface to form a balanced layer of coating.
3. Baking and curing
After spraying the workpiece through the conveyor chain into the 180 ~ 200 ℃ oven heating, and insulation corresponding time, (15-20 minutes) so that the melting, leveling, curing, get the surface effect of the workpiece we want. (Different powders are different in baking temperature and time). This is the curing process that should be noted.
After the coating is cured, remove the protective material and trim the burrs.
After curing, the workpiece is checked daily mainly for appearance (whether it is flat and bright, and whether there are defects such as particles and shrinkage) and thickness (controlled at 55-90μm). The workpiece detected with defects such as leakage spray, pinhole, bruise, bubble, etc., rework or repaint.
The main difference of various powder spraying processes is the powder, and then adjusting the temperature and time according to the powder. the best JIIPOWER can provide is the powder produced by FORD designated supplier, which has an excellent performance in various tests, and no customer has reflected the quality problem yet.
Although the electroplating process has excellent performance, it has been eliminated by most countries due to the large environmental pollution and replaced by the better and more environmentally friendly electrophoresis process.
Electrophoretic paint film has the advantages of plump, uniform, flat and smooth coating, and the hardness, adhesion, corrosion resistance, impact performance, and penetration performance of electrophoretic paint film are obviously better than other coating processes.
1. Using water-soluble paint, using water as the dissolving medium, saving a lot of organic solvents, greatly reducing atmospheric pollution and environmental hazards, safety, and health, while avoiding the hidden danger of fire.
2. High painting efficiency, small paint loss, the utilization rate of paint can reach 90% to 95%.
3. uniform coating film thickness, strong adhesion, good coating quality, uniform, and smooth coating film can be obtained at various parts of the workpiece such as an inner layer, depression, weld seam, etc., solving the coating problems of other coating methods for complex-shaped workpieces.
4. High production efficiency, the construction can realize automatic continuous production, greatly improving labor efficiency.
5. Complex equipment, high power consumption, high temperature for drying and curing, complicated management of paint and coating, strict construction conditions, and wastewater treatment are required.
6. Only water-soluble paint can be used, the color cannot be changed during the painting process, and the stability of the paint is not easy to control when stored for too long.
7. Electrophoretic coating equipment is complex, with high technological content, and suitable for fixed color production.