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How to control the thickness of the electrostatic powder coating
Customers like the goods because of its beautiful colors and a variety of shapes. But there are much difficult of painting and control for the thickness of workpiece because the complex of the workpiece surface. Even the goods have complex shape there are also the coating on its decorative surface has mandatory provisions and must be strictly observed.
In actual production, influence by the static painting device ang shapes of the workpiece surface, there are difficult to control the painting precision. For the characteristics of the painting, there are some methods can be followed to control the thickness of the coating precision.
1. Choose the suitable suspension modes and hanger
The key factor to control the thickness of powder coating is to choose the right hanging device according to the shape of workpiece profile, it can not only improve the quality of workpiece coating, but also reduce the manual operators with handle powder work. In particular, the distance of the hanging material can adjust the thickness of the powder coating, the spacing of the hanging material is generally required: the width of the aluminum profile = the spacing of the workpiece profile.
2. The contact between workpiece and the hanger
Because of the lack contacts between workpiece and hanger, will seriously affect the powder coating efficiency and the quality of the powder coating, cause the workpiece with low coating efficiency and unevenly coating thickness. Causes a lot of pressure to the recovery system, made the overspray powder can't be recycled and hung outside the powder booth, both reduces the powder utilization ratio and pollute the environment.
For poor contact between workpiece and the hanger, the products will have different powder coating thickness. In some places, because the coating is too thick, there will be orange peel, pinhole, flow mark and other defects, color and gloss will also be affected, and under the natural light line visual inspection sand grain powder profile has more obvious zebra linear defects. Therefore, it is necessary to ensure a good electrical conductivity between the workpiece and the hanger.
3.The convey speed and the production processes
The convey speed and the production processes are played an important role in power coating processing, determine the thickness of the powder coating. The general height of the lifter requires：Standard height = workpiece height + 200mm. The more complex shape of the workpiece is, the closer the distance between the spray gun and the workpiece is, the smaller amount of powder required and the lower voltage. On the contrary, the simpler shape of the workpiece, the farther the distance between the spray gun and the workpiece, the greater the powder output and the higher the voltage.
4.The method of manual powder repair
Due to the complex of the workpiece surface, during powder coating processing, the Interior Angle, transverse groove and other complex place that the automatic spray gun can’t coating completely, so the manual powder repair is necessary. When the nozzle of the hand spray gun is facing the place to be repair sprayed on the workpiece, the transmission pressure is adjusted too much, and the distance between the hand spray gun and the workpiece is too close, which may easily cause the appearance of orange peel, flow mark, pinhole, gun dotting and fat edge on the workpiece surface. In general, when the nozzle of the handgun is facing the place to be sprayed on the workpiece, the transmission pressure is 1.2 ~ 1.8bar, and the distance between the handgun and the workpiece should be controlled within 80 ~ 150mm.
Common in the process of powder coating inequality is mainly a venturi powder pump parts caused by unclean, because powder compression pump suction pipe, easy generation product powder, glue powder and cause congestion, lead to powder pipe receiving force affected, thus affect the thickness of the workpiece, usually a powder booth operators should be timely check each part of the venturi powder pump clean.