Troubleshooting to overall electrostatic coating operation

Posted by: FEIHONG Powders |on July 5, 2018

Problem, Cause and Remedy

PROBLEM	CAUSE	REMEDY
Poor charging-inadequate powder build or wrap on part	High-voltage source not providing enough KV at charging electrode or grid.	Check high voltage source is on. Systematically check electrical continuity from voltage source to electrode (grid) including cable, resistors and fuses. Replace missing or broken electrode (grid). Clean electrode (grid) insulated by powder build or impact fusion.
	Poor ground	Check ground from conveyor rail (or rub bar when used) through hanger to part. All contact areas must be free of powder build, heavy grease and other insulating material.
	Powder delivery (feed) is too high	Turn down powder feed until all material passing through charging corona (field) is adequately charged
	Excessive moisture in powder booth air	Moisture in humid air will tend to dissipate humidity in the powder spray area
	Powder too fine	Too much reclaim added to virgin powder. Virgin powder pulverized too fine by manufacturer.
	Powder type or formula	Some resin types charge better than others and some formulas are designed for thin film application. Check with your powder supplier.
	Powder delivery air too high Powder blowing by part.	Turn down air setting or move gun position farther away from Part
Poor penetration-powder will not coat Faraday Cage areas(holes, grooves, channels, inside corners, and recesses).	Powder delivery too low	Turn up powder delivery air setting. Use gun barrel extension.
	Poor ground	Check ground
	Powder spray pattern too wide	Select smaller deflector or use suitable slotted barrel and cover. (Consult your equipment supplier.)
	Voltage too high	Turn voltage setting down so powder builds on part edges and leading surfaces do not repel powder from corner.
	Powder delivery velocity too high	Turn air settings down so powder/air stream does not blow powder out of corners.
	Poor gun placement	Adjust gun position so powder cloud has a direct path to recess area.
	Powder too fine	Too much reclaim added to virgin powder. Virgin powder pulverized too fine by manufacturer.
Back charging-powder layers are repelled from part in spots.	Voltage too high	Turn down voltage setting.
	Gun positioned too close to Part.	Change gun placement away from part.
	Poor ground	Check ground
	Powder too fine	Too much reclaim added to virgin powder. Virgin powder pulverized too fine by manufacturer.
Powder picks up a random charge through powder or in fluid path. Reverse charging usually through reclaim system	Powder booth air too dry	Adjust powder spray area humidity. See chart for optimum conditions
	Poor delivery and/or reclaim usually through equipment ground.	Provide ground for all equipment
Powder feed spurting or slugging-interrupted powder feed	Insufficient air pressure or volume	Check air supply. Air supply piping to equipment is large enough. Enough air volume when other equipment such as reverse air cleaning in reclaim housing pulses, air pressure to powder feed does not drop
	Hoses kinked, flattened, or too long.	Check powder feed hoses
	Hoses, pump venturis , or guns clogged with powder	Clean hoses, venturis, and guns. Check air supply for moisture that causes powder compaction. Check powder free flowing properties. Check spray booth air humidity. Check powder supply for contamination. Check reclaim sieve
Poor spray pattern-not a symmetrical powder cloud (not applicable when using special deflectors for desired effect)	Worn E/S gun parts.	Replace worn feed tubes, orifices, deflectors, and covers
	Impact fusion build. Delivery (feed) air too low	Clean gun parts as needed. Check air supply. Increase air for powder feed.
	Hoses, venturis, or gun blocked with powder	Clean hoses, venturis, and guns