Electrostatic Powders Spray Coating

Electrostatic Powders Spray Coating

 

Electrostatic Powders Spray Coating is a surface treatment method for spraying polyester powder on the workpiece. The full name of spray coating is also the electrostatic powder spray coating of electrostatic powder, and its treatment process is a decorative technology that uses a more common metal surface treated in the 1980s. Compared with the surface treatment of ordinary paint, the technology is reflected in the advanced technology, energy saving, efficient, safe and reliable, and colorful. Therefore, it is often applied to light industry and household renovation. The working principle is to charge the plastic powder through the high pressure electrostatic apparatus. Under the action of the electric field, the coating is sprayed to the surface of the workpiece, and the powder will be uniformly adsorbed on the surface of the workpiece, form a powder coating; and the powdery coating passes through After the high temperature baking, the plastic particles will melt into a final protective coating of different effects; it is firmly attached to the surface of the workpiece. Spray powder mainly has acrylic powder, polyester powder, and the like.

 

Advantage

No need to parenly, the construction has no pollution to the environment, the body is none to the human body; the quality of the coating is excellent, the adhesion and mechanical strength; the spray coating is short; the coating resistance resistance is much higher; no primer; The construction is simple, low for workers' technical requirements; cost is lower than painting technology; some construction situations have clearly proposed to use electrostatic spray process treatment; there will be no common flow in painting process during electrostatic powder spraying.

 

Process principle

The powder coating is adsorbed on the workpiece by using corona discharge phenomenon. The process is such that the powder coating is fed from the powder powder to the spray gun, and the high pressure generated by the high voltage electrostatic generator is added to the front end of the gun. Because the corona discharge, a dense charge is produced near it, the powder is bone When discharged, a charged coating particles are formed, and it is attached to the working parts opposite to the polarity, and the total charge accumulation is also increased as the powder is increased, and the charge accumulation is generated, and when it reaches a thickness The action does not continue to adsorb, so that the entire workpiece obtains a thickness of the powder coating, and then heats the powder, the powder is fused, level, cured, i.e., form a hard coating film on the surface of the workpiece.

 

Process

1, pre-processing:

Objective: To remove oil, dust, rust, rust, and a "phosphating layer" of the spray coating at the surface of the workpiece and can increase the adhesion of the spray coating layer.

Main process steps: remove oil, rust, phosphat, passivation. After the workpiece is processed, there is no oil, rust, dust, but also generates a layer of uniform and rough surface on the white-white glossy surface, which can prevent rust and increase the spray layer. Attack.

 

2, electrostatic spraying

OBJECTIVE: The powder coating is uniformly sprayed onto the surface of the workpiece, and the special workpiece (including a position that is prone to generate electrostatic shield) should use a high performance electrostatic sprayer to complete the spray.

 

Process steps:

Using electrostatic adsorption principle, a layer of powder coating is sprayed evenly on the surface of the workpiece;

The falling powder is recovered by recycling system, and it can be used after sieve.

 

3, high temperature curing

OBJECTIV: The powder coating of the workpiece surface is heated to a predetermined temperature and insulates the corresponding time, allowing melting, leveling, cure, resulting in the surface effect of the workpiece we want.

 

Process step: Push the sprayed workpiece into the cured furnace, heated to a predetermined temperature (generally 185 degrees), and insulates the corresponding time (15 minutes); the furnace is taken out to obtain a finished product. The general workpiece is different, and the temperature of the temperature is also different.

Tip: Heating and control system (including electric heating, fuel, gas, coal, etc.) + insulation box = cured furnace.

 

4, release the cooling

The cooled is cooled to cool the results of the spray process to return to a process of normal temperature.

 

5, decorative treatment

OBJECTIVE: To achieve a special appearance effect after the electrostatic sprayed workpiece is: a variety of wood grain, pattern, suction, etc.

Process step: Handling; transfer and other processing processes.

 

Spray product inspection standard

 

1. Purpose

Make sure the spray product test is standardized to meet the quality control of the product in uniformity.

 

2. Scope

This standard is suitable for inspection and on-site quality control and inspection of spray products.

 

1. Trial spray spray product inspection method

New products or new modified spray products, first checking. The technical department and the inspection department were tested and confirmed. Test the spray-plastic product structure in line with design requirements; external wire printing of spray products meets design requirements, including silk printing positions, colors, sizes, and clarity.

 

1.1 Structure of spray products Basic requirements: Size and assembly of spray products should comply with drawings requirements, in line with corresponding technical requirements and national standards.

 

1.2 Structural inspection method of spray product: Sprife is given a test, verifying the structure of the product, and requires convenient installation of the spray product. The reset semi-finished product is required to install the hole position, the screw mount can be fastened, not skewed: expose the position, height, gap outside the sprayed product; it is suitable; not allowed to be offset to the edge of the product or even dew On the sprayed product, the lower cover is closely fitted, the installation is convenient; the rivet in the spray product is not allowed to be loose or even fall off. The test is qualified and can continue to be inspected. The trial is unqualified, and the second product should be resemble, if the same problem occurs, it is unqualified according to bulk.

 

1.3 appearance of spray products

The appearance uses a visual measurement, and is tested in normal or corrected vision.

 

1.3.1 Spray Color: The color of the spray should be consistent with the selected sample or color plate, and the surface of the product after spray is uniform, and there is no significant color difference.

 

1.3.2 Spraying layer thickness: The thickness of the spray coating should meet the design and use requirements, the spray thickness is uniform, and the adhesion is strong.

 

1.3.3 Product Cleaning: The surface is visible inside and outside, which should be cleaned, no stains, oil stains, etc., any dirt, which affects the appearance, nor is it a white trace left behind the finger.

 

1.3.4 Spray Product External Silk Print Inspection Requirements

Check the screen printing of the spray product and the color matching of the design, the silk screen is clear, and there is no defect such as a shorter printing, leakage, color inconsistency, non-identification or defect.

 

1.3.5 Exterior Defect Inspection Requirements of Spray Products

 

1.3.5.1 Water leakage, rust: spray products do not allow water leakage, and the spray product inspection must be the waterproof test. Each batch of spray products extract 2% is waterproof test, put into toilet paper in the bottom of the box, then install the sprayed product, tighten, and seal the plug hole with the tape, the sprayed product is top, front, back The faucet is underfighter for 20 minutes, then dry the surface of the sprayed product, checking the spray product, checking if the toilet paper is soaked, not soaked. After the waterproof test, all products are opened, and the bottom of the box is placed under strong light, and the four-angle in the bottom of the box does not allow light-transmitting phenomena. There is no crack, deficit, and loopholes; the upper and lower cover combined surface should be flat. The chamfer is smooth, not allowed to have no gap, cracks, deformation; waterproof rubber pad size is suitable, not allowed to be aging, uneven and damaged, the rubber pad must be consistent with the sample.

 

The surface of the spray product does not allow rust phenomena, and the surface of the spray product is homogeneous. It cannot be sprayed and leakage, which can cause rust of spray products.

 

1.3.5.2 Damage Deformation: The surface of the spray product is not allowed to be injured, deformed, and the surface should be smooth and unfolded.

 

1.3.5.3 Scratch: Do not allow rubbing due to friction.

 

1.3.5.4 Particles: The surface of the spray product does not have a plastic particles, silk printing ink spots, bumps, convex traces or flow plastic traces, allow dispersion and small amounts of particles.

 

1.3.5.5 Pit: The surface of the spray product cannot be formed, allowing dispersion and trace.

 

1.3.5.6 Scratches: The surface of the spray product cannot be scratched, and there is no more scratched, and the bottom plate cannot be leaked; the surface of the spray product cannot be scratched, only the dispersion and trace are allowed.

 

1.3.5.7 Gap: The spray product is able to waterproof, and there is also a requirement for gaps.

 

2. Check the results handle:

Structural inspection of spray products, two unqualified trials, judgment is unqualified by batch; in the case of implication rate of the spray product, the rework process will be returned to the rework; if the appearance rate of the spray product <95%, the judgment is unqualified. Spray product inspection is unqualified, filling out unqualified reports and reporting the Quality Control Center.