How to Deal with Impurities in the Coating During Electrostatic Powder Spraying?
Powder electrostatic spraying refers to the electrostatic generator releasing high-voltage static electricity (negative electrode) to the space in the workpiece's direction through the electrode needle at the gun mouth. The high-voltage static electricity ionizes the mixture of powder and compressed air ejected from the gun mouth and the air around the electrode (with a negative charge). The powder is driven by an electric field and compressed air pressure to the workpiece's surface, and a uniform coating is formed by electrostatic attraction. AEM Deposition provides all kinds of metal powder. The details are as follows:
When we carry out electrostatic powder spraying, impurities often appear in the coating. So how did this happen? How to deal with it?
The typical coating impurities mainly come from the particles in the powder spraying environment and other impurities caused by various factors. The causes and solutions are as follows:
(1) Impurities in curing furnace
Solution: Thoroughly clean the curing oven's inner wall with a wet cloth and vacuum cleaner, focusing on the gap between the suspension chain and air duct. If it is a large black particle impurity, it is necessary to check whether the air supply pipe's filter screen is damaged and replace it in time.
(2) Impurities in powder spraying room
Cause: It is mainly dust, clothing fiber, equipment abrasive, and dust spray system scale.
Solution: Use compressed air to purge the powder spraying system and use a wet cloth and vacuum cleaner to thoroughly clean the powder spraying equipment and powder spraying room.
(3) Impurities in suspension chain
Cause: It is mainly because of corrosion of suspension chain oil baffle and primary sling water plate (made of the hot galvanized plate) by pretreatment acid and alkali vapor.
Solution: Clean these facilities regularly.
(4) Powder impurity
Causes: Mainly due to excessive powder additives, uneven dispersion of pigments, powder points caused by extrusion.
Solution: Improve the quality of the powder, improve the way of powder storage and transportation.
(5) Pretreatment impurities
Cause: It is mainly triggered by large particle impurities caused by phosphating slag and small impurities affected by yellow rust of phosphating film.
Solution: Clean up the slag in the phosphating tank and spray pipeline in time and control the phosphating tank solution's concentration and proportion.
(6) Water quality impurities
Cause: Mainly impurities caused by excessive sand content and salt content in pretreatment water.
Solution: Add water filter and use pure water as the final two-stage cleaning water.