2026-01-26
Key Points About Spray Coating Processing
The production of the powder coating spraying chamber is a process in the spraying production process. The quality of the sprayed surface of the profile lies in the control of various process parameters during the spraying process. The powder output and the atomization air volume are two technical indicators. Before the formal powder spraying, a few trial sprays should be conducted. At this time, the amount of powder and the uniformity of powder distribution can be observed at both ends of the spraying chamber. At this point, the powder runs in a straight line within a range of 10cm - 15cm from the end of the spray gun, and exists externally in the form of atomized powder. The powder adsorbed on the profile surface is actually the powder with this atomization effect. The distance between the spray gun and the profile is controlled according to whether there is such atomization effect of powder.
(1) Spray gun position.
The spray gun should be kept at a certain inclination and tilted towards the direction of the profile movement. The spray guns should be arranged vertically and parallelly, with the ends kept straight. The spray guns should not overlap. The positions of the upper and lower spray guns should ensure that the powder covers all the profiles.
(2) Fluidization pressure control.
The function of a fluidized bed is to make the powder form a suitable fluidized state under the action of the airflow. The sensation is similar to that of liquid flow. The simple operation is to check whether the fluidization has reached an adequate state. When stirring the powder with hands or sticks, there is no resistance felt. The fluidization makes it easy to suck the powder into the pipeline. Under the action of the accelerating wind, a misting effect will be produced. Insufficient or excessive pressure will result in insufficient fluidization.
(3) Powder recovery.
The powder adsorbed on the mold surface only accounts for about one-third of the total powder output of all spray guns. During the spraying process, a large amount of powder is scattered in the spraying room. The recovered powder must be mixed with the newly added powder in an appropriate ratio to achieve good results. Therefore, the powder should be recovered in a timely manner.
(4) Sealing of the spray chamber.
The powder is easily contaminated by suspended solids in the external air. After powder spraying, the surface of the profile is prone to agglomeration or pinholes, which affects the flatness of the profile surface after baking. Therefore, the spraying chamber should be closed to prevent the intrusion of contaminants.
(5) Any remaining powder in the airway should be cleared promptly. If it is not used for a long time, it may become caked and the powder could spurt out, thereby affecting the spraying effect.
(6) Backup powder container.
When used for powder replacement, it can effectively improve labor efficiency. The spare powder tank should be properly maintained for dust and moisture prevention, and during the spraying process, the quality of the remaining powder in the tank must be ensured.
(7) Additionally, attention should be paid to the powdering process.
Although the technical parameters for the spraying process have been calibrated before normal production, continuous monitoring of the profiles is still necessary through the powder replenishment window. Powder should be replenished promptly in areas where the powder is thin or where there is no adsorbed powder. Since the manual friction gun throws more powder than the automatic gun, the manual friction gun can be thrown more quickly by hand.
Additionally, due to the inherent structure of certain profiles, some dead corners may occur during the powder spraying process. Even if additional powder is added, it cannot achieve the normal effect. These positions should be distinguished. Do not blindly add powder; otherwise, there will be excessive powder and excessive film thickness, which will affect the surface quality of the profiles and cause waste powder. These positions are mostly located on profiles with deep grooves and narrow widths, and these grooves are mostly on the non-decorative surfaces of the profiles. The overall appearance of the profiles is not much affected because the two sides within the grooves are at the same pole, and the distance is too close, forming an opposing electric field, namely the Faraday shielding effect, which hinders the adsorption of powder in the grooves.
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