Tile display rack into the paint oven paint, the purpose is to protect and decorate the display stand. But because of different materials, materials, different molding process and other factors, the process is slightly different.
Under normal circumstances, stamping or injection molding surface is better, no fill soil, grinding process; cast parts surface defects are more, there are many pores, depression, filling defects and other defects, the need for soil grinding process to Improve the surface roughness.
The role of each process
1. PreparationsMetal parts and non-metallic parts due to different materials, treatment in different ways.
1.1 Tile display metal material before processing
Degreasing Washing Washing Washing Surface conditioning Chemical or electrochemical treatment Washing Baking
Degreasing is to remove the surface of the workpiece oil, adsorption layer. Acid etching is to remove the surface oxide.
This process depends on the surface conditions of the workpiece. Surface adjustment of the workpiece surface molecules can be activated to promote the surface chemical or electrochemical film formation.
The purpose of washing is to clean the residual surface of the workpiece, so as not to bring into the next slot, the contaminated liquid.
Chemical or electrochemical treatment: through chemical or electrochemical reaction, the workpiece surface to generate a uniform layer of protective layer to improve the corrosion resistance of steel surface. Different steel materials used in chemical or electrochemical methods are different.
In general, as the paint before the treatment, magnesium alloy parts using chemical oxidation or phosphating treatment; aluminum alloy parts using chemical oxidation or anodizing; steel parts using phosphating treatment.
The purpose of baking is to remove the surface of the workpiece moisture, so that the workpiece surface to achieve a thorough drying. Pretreatment quality of the film quality of a greater impact, especially on the coating adhesion. Therefore, pre-treatment is very critical before a painting process.
2. Covering does not require coating partThe purpose is to not need to protect parts of the coating.
At present, most of the workpiece with a masking fixture, but for the complex shape of the workpiece, some parts can not be done by shielding the fixture, even for the simple shape, large size, less shielding parts and other parts, are indispensable to this process.
The choice of materials used in the screening should be considered after the baking process, which requires temperature resistance, and must ensure that the shielding material baked after the peelability in order to facilitate the dressing.
3. Clean the dustUsing manual or automatic dust removal process, will be attached to the surface of the dust, adhere to completely remove the clean, to ensure that the adhesion between the workpiece and the coating.
Commonly used dust removal devices are compressed air and electrostatic dust.
4. Spray the primerA spray primer is a media layer between the object to be coated and the coating thereon.
A. has a high corrosion resistance.
B. has a certain filling.
C. easy to show surface defects, easy to fill soil operations.
In the painting process, the need to control the spray distance, paint viscosity, spray pressure and environmental temperature and humidity parameters.
The basic composition of paint.
Different materials are not the same choice of primer. Depending on the composition of the coating, the nature of the coating and other factors.
A. Film-forming materials (oil, resin)
B. Pigments (coloring pigments, physical pigments, anti-rust pigments)
C. Solvent (true solvent, cosolvent)
D. additives
Film forming material
1. Oil (dry oil, semi-drying oil)
Iodine value to measure the degree of oil saturation and drying rate. The so-called iodine value, that is, under standard conditions, one hundred grams of oil can absorb iodine grams. Iodine value of less than 100 grams of oil is called non-drying oil. Iodine value of between 100 to 140 grams of semi-dry oil called, more than 140 grams of dry oil called.
2. Resin: a natural resin, synthetic resin.
Pigment
1. coloring pigment: in the paint from the main cover and decorative role. Can improve the physical and chemical properties of the film.
2. Physical pigments: also known as filler pigment, is a no cover ability and coloring ability of the powder, can reduce the cost of paint, increase the thickness of the film, improve the mechanical properties of the film.
3. Anti-rust paint: to prevent corrosion of metals.
Solvent
1.solvent: an organic solvent with the effect of dissolving the paint.
2. Solvent: with the real solvent used in conjunction with a certain ability to dissolve the paint itself does not have the ability to dissolve the paint solvent.
Additives
5. Baking (standing)Baking purpose is to make the film through a certain temperature, a certain time after baking can be the next process.
The purpose of standing is to make the coating fully flattened to improve the overall appearance of the coating after the flatness and fullness.
At present the coating manufacturing each coating between the baking process; each between the coating without baking, just standing for a certain time to the next step. There is also a direct use of ultraviolet radiation to achieve the purpose of the process of drying. The choice of drying methods must be based on the properties of the coating itself, the nature of the material to be coated and other factors to be considered in order to find a suitable coating process.
Drying mechanism of film
1. Physical drying
A. solvent evaporation: evaporation by solvent evaporation film.
B. Melt Curability: The paint melts after heating and solidifies after cooling.
2. Chemical drying
A. Oxidative drying: the coating by the role of oxygen in the air polymerization hardening.
B. Thermal Polymerization Drying: The resin hardens after heating.
C. Catalytic Polymerization Drying: The catalyst is used to cure the resin at ambient temperature.
D. Radiation polymerization Drying: coating by electron beam or ultraviolet radiation, free radical polymerization initiated by hardening.
Baking equipment commonly used tunnel-type oven, box-type ovens, horizontal ovens, and so on.
6. fill soilThe fill agent is a defective filler material, with the ability to increase the surface smoothness.
Soil agents in the pigment composition of more resin composition is less, it has a good filling.
There are single-component and two-component two types.
One-component fill soil agent is relatively simple, simply adjust the soil to the appropriate viscosity can be carried out.
Two-component soil additives in the use must pay attention to fill agent and hardener ratio, improper ratio can directly affect the performance of the coating. General deployment ratio for the fill agent: hardener = 100: 1 ~ 3 (weight ratio)
7. GrindingThe purpose of grinding:
A. Polishing the fill agent to improve the appearance of the next coating flatness.
B. The primer I surface evenly polished again, can improve the adhesion of multi-coating.
Grinding process requires uniform grinding, can not reveal the bottom of the material.
8. Spray primer IIeffect:
A. Fill the pinholes slightly.
B. Cover the surface of the patch when the traces of soil.
C. Add the adhesion between the soil agent and the top coat.
D. Reduce the use of topcoats.
E. As the intermediate layer between topcoat and primer I, the luster and fullness of the topcoat can be increased.
9. Spray the topcoatWith the protection and decoration ability.
Topcoat and primer compatibility is very important. Under normal circumstances, the primer and finish with the same paint suppliers. If special circumstances, must be carried out after supporting the paint test can be used for production.
10. CheckCheck whether the coating defects. Defects in the customer specifications.
Painting common defects are: impurities, color, pinholes, hair, rhyolite, blistering, rough, orange peel and so on. Each defect has its causes and prevention methods.
The purpose of the inspection is to promptly identify problems, timely feedback, timely problem-solving.
11. Finished product exhibition stand baked.
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