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A few more details about powder coating procedure as following from Ming Feng Lighting Co.,Ltd as following,


Surface pretreatment:

(1) 1. Oil removal; 2 water washing; 3. Rust removal; 4. Water washing; 5 meter adjustment; 6. Water washing; 7 phosphating; 8. Water washing; 9 water washing;

10 drying;

(2) Purpose and importance of pretreatment: the purpose of pretreatment is to get a good coating due to the above stamping

During manufacturing, processing, handling and storage, there will be grease, oxide, rust scale, dust, rust and corrosion on the surface, if

If not removed, it will directly affect the performance and appearance of the film, so the pretreatment plays a very important role in the coating process.

(3) Significance of pretreatment: coating pretreatment, coating and drying are the three main processes of coating process, among which

Management is the basic process, which has an important impact on the whole coating quality, coating service life and coating appearance

The workpiece surface after grease, rust removal, phosphating and other processes is clean, uniform and free of grease

1. Degreasing: mainly mineral oil, lubricating grease, animal and vegetable grease, such as touching by hand during operation and handling

And other oils and fats seriously reduce the adhesion of most coatings, affect their drying, and reduce the hardness and gloss of coatings

Low. Remove the oil stain on the workpiece with alkali solution. The main alkali is NaOH, NaHCO3, etc; Can buy special

The degreasing powder of the door is then prepared into an aqueous solution; Saponification of soap;

2. Rinse with clean water to prevent the solution in the previous process from polluting the next process. Clean water must be alive

Moving).

3. Derusting yellow rust can promote the spread of corrosion products under the coating and make the coating lose shielding and moisture impermeability. In high

Under the condition of high temperature and humidity, it can lead to early damage of coating and metal, loose yellow rust, poor adhesion, and can fall off with the coating.

There are many methods to remove rust, such as alkali method, acid method, mechanical method, electrolytic method, etc. the common one is alkali method. Remove with chemical solution

To remove the scale and rust on the workpiece surface, sulfuric acid and oxalic acid are generally used. It can also be supplemented by ultrasonic cleaning.

4. Abbreviation of surface adjustment (neutralization) surface adjustment: use acid (or alkali) solution to remove the excess on the surface in the derusting process

Alkali (or acid), adjust the pH to neutral as much as possible, that is, pH = 7; Function: accelerate phosphating speed and refine phosphating junction

Crystal, increase the crystallization point of phosphating;

5. Phosphating is the central link of coating pretreatment, which is treated with orthophosphate solution of manganese, zinc and cadmium phosphate

A layer of insoluble phosphate protective film is formed on the surface of the metal workpiece, and the formed phosphate film system has fine pores

The compact structure increases the surface area of the workpiece, increases the contact area of the coating, and produces favorable contact between the phosphating film and the coating

Mutual penetration greatly improves the adhesion of organic coating to workpiece. The phosphating film formed by phosphating is a stable non conductive layer

The electric isolation layer changes the metal surface from good conductor to bad conductor, inhibits the formation of micro battery and effectively prevents the corrosion of coating

Erosion. The common methods of phosphating are divided into high temperature phosphating (70 ~ 90 ℃), medium temperature phosphating (50 ~ 70 ℃) and high temperature phosphating according to the treatment temperature

Phosphating at normal temperature (20 ~ 30 ℃). The phosphating film is generally black.

6. The above pretreatment processes are basically carried out in the water tank. And each process has time regulations.

Drying moisture and preparing for painting; 4、 Before hanging, the appearance of unpainted workpieces shall be inspected before going online; It's big

Some are defective products that have been painted. Check whether they can be sprayed directly or remove the old paint; Old paint removal method, solvent

Soak and clean or remove with special paint remover. 5、 Grinding is an unnecessary process to remove granular impurities on the surface and increase a certain amount

Roughness to increase paint adhesion; First pass: 400# water sandpaper second pass; 800 # water sandpaper or finer

6、 Hang the product on the hanger, which is conductive and moves with the assembly line; The hanger shall be a conductor and shall be grounded

Ground (for electrostatic coating); Hangers are generally customized according to different characteristics of products; A large number, the whole pipeline turnover

use

7、 Blow dust to remove surface dust, dandruff, etc; Compressed air;

8、 Manual spraying pre spray the parts with low potential (such as shadow parts, concave parts, etc.) before automatic spraying, but also

It is a necessary choice without automatic spraying equipment, with low efficiency, limited production capacity, many unstable factors and high defect rate,

The equipment for manual spraying mainly includes air compressor, gas transmission pipe, air oil-water separator and spray gun,

Paint container, spray booth, etc.

The types of spray gun are: 1. Gravity type; 2. Suction type; 3. Pressure feeding type

9、 Disk spraying disk automatic spraying belongs to the category of electrostatic spraying, which uses the connection between the spraying device and the grounded workpiece

The electrostatic force is generated by the high voltage difference, the coating is thrown out by the centrifugal force generated by disk at a fixed speed, and the coating is applied after electrostatic atomization

On the workpiece, the disk moves up and down to cover the whole workpiece range; the disk spraying equipment is actually a rotary disk electrostatic spraying equipment,

It can also be called centrifugal electrostatic atomization equipment. The rotating speed of the rotating disc is 5000 ~ 60000 R / min and the working voltage is 70 ~ 120kv,

The electrostatic coating is driven by air motor and used for electrostatic coating. The resistance value of the coating shall be controlled within a certain range;

10、 Paint repair inspection: repair the spraying defects (less paint, thin paint, etc.) of disk, which can be found in time through inspection

The defects of disk spraying shall be and adjusted, and the positions that cannot be sprayed by disk shall be sprayed;

11、 Bake in the preheating furnace at a lower temperature (e.g. 80 ~ 150 ℃) to evaporate the solvent and level the wet paint film

12、 The main furnace is forced to bake at a higher temperature (such as 180 ~ 185 ℃) to dry the paint, and the faster the assembly line is

Fast, the higher the temperature needs to be adjusted;

13、 Inspection of finished products;


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