What is the reason for the inability to coat recesses in powder coating? The barrier of static electricity.
Only the inner sides of the box and the bottoms of the deep ribs do not have a film thickness. I will explain the Faraday cage phenomenon that prevents static electricity from entering and the countermeasures.
Only the inside of the box and the bottom of deep ribs do not receive powder no matter how much is blown. This is not a problem with the gun; it is caused by the nature of static electricity. When the depth of the recess exceeds 1.5 times its width, the powder cannot reach it. ────────────── ■ Cause of occurrence Electric field lines concentrate at the corners of the entrance of the recess and do not penetrate inside. Charged powder is attracted to the corners, leaving the back uncoated. ■ Truth Increasing the voltage has the opposite effect. At high voltage, adhesion at the entrance increases, further hindering access to the interior. ■ Improvement measures Lower the voltage and increase the air pressure to mechanically push the powder in. Depending on the shape, switching to solvent-based powder coating is reliable, and preliminary test coatings are effective. Please utilize the materials summarizing suitable shapes for powder coating.
- Company：永和工芸
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