How to Deal with Impurities in the Coating During Electrostatic Powder Spraying?
Powder electrostatic spraying refers to the electrostatic generator releases high-voltage static electricity (negative electrode) to the space in the direction of the workpiece 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 negative charge). The powder is driven by electric field and compressed air pressure to the surface of the workpiece, and a uniform coating is formed on the surface of the workpiece by electrostatic attraction. AEM Deposition can provide 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 common coating impurities mainly come from the particles in the powder spraying environment, as well as other impurities caused by various factors. The causes and solutions are as follows:
(1) Impurities in curing furnace
Solution: thoroughly clean the inner wall of curing oven with wet cloth and vacuum cleaner, focusing on the gap between suspension chain and air duct. If it is a black large particle impurity, it is necessary to check whether the filter screen of air supply pipe 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 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 the product of corrosion of suspension chain oil baffle and primary sling water plate (made of 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, etc.
Solution: improve the quality of powder, improve the way of powder storage and transportation.
(5) Pretreatment impurities
Cause: it is mainly caused by large particle impurities caused by phosphating slag and small pieces of impurities caused by yellow rust of phosphating film.
Solution: clean up the slag in the phosphating tank and spray pipeline in time, and control the concentration and proportion of the phosphating tank solution.
(6) Water quality impurities
Cause: it is mainly impurities caused by excessive sand content and salt content in the water used for pretreatment.
Solution: add water filter and use pure water as the final two-stage cleaning water.