TROUBLESHOOTING
GUIDE
Powder Coating Problems and Troubleshooting Guide
Trouble
Possible Causes
Solution
Poor charging - inadequate powder film thickness or poor coverage (dissipate)
High voltage source not providing KV at charging electrode
a) Check if high voltage is on, systematically check continuity from voltage source to electrode, including cable resistors and fuses.
b) Replace missing or broken electrode.
c) Check electrode insulated by powder build-up 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 up, heavy grease and other insulating materials.
Poor delivery rate is too high
Reduce powder delivery rate until material is adequately charged.
Excessive moisture in powder booth air
Moisture in humid air will tend to dissipate the charge on the powder particles. Control the humidity in the powder spray area.
Powder too fine
a) Maintain consistent blend of virgin and recycled powder.
b) Check particle size of powder. Contact your powder supplier.
Powder type or formula
Some powder formulations charge better than others and some formulas are designed for thin application. Contact 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 holes, grooves, channels, inside corners and recesses (faraday cage)
Powder delivery too low
Turn up powder delivery air settings.
Poor ground
Check ground. Refer to "poor ground above".
Incorrect powder spray pattern
a) Adjust powder spray pattern
b) Try alternative nozzle selections.
Voltage too high
Turn down voltage setting down so that surfaces closer to gun do not repel powder from corners.
Powder delivery velocity too high
Turn air setting down so powder air stream does not blow powder into corners.
Poor gun placement
Adjust gun position so powder cloud has a direct path to recessed areas.
Poor blowing out
of hopper
Fluidization air pressure too high
Adjust air regulator to lower pressure to fluid bed.
Insufficient hopper ventilation.
a) Check hopper vent for plugging.
b) Check vent assist device for obstruction and proper air supply.
Insufficient air pressure
Check hopper fluidization air supply. Increase air pressure as required.
Plugged membrane
Check membrane for plugged pores from dirty or oily air supply.
Obstructed membrane
Check bottom of hopper for obstructions.
Compacted powder on membrane
Manually loosen powder and fluidize well with clean, dry air
No air percolating through powder surface
Insufficient
powder feed
Powder not fluidizing
Refer to 'No air percolating through powder surface' and poor fluidization / air blowing large holes through powder surface above.
Obstruction of powder delivery system
a) Check suction tubes, powder pumps, hose and gun.
b) Check air supply, adjust air setting to pump and gas.
c) Check powder supply for contamination.
Back ionization-powder particles are repelled from part
Voltage too high
Turn down voltage settings.
Gun positioned too close to part
Change gun placement farther away from part.
Poor ground
Check ground. Refer to 'poor ground' above.
Excessively heavy powder build up
Refer to 'powder delivery rate is too high' above.
Powder hose too long or has too many sharp bends.
Reduce powder hose length, modify hose runs.
Low air pressure
Check air supply; adjust air setting to pump and gas.
Properties of the Cure Film
Pinholes in
the film
Moisture content of the powder too high
a) Check the powder storage conditions.
b) Check the humidity of the air supply.
Air inclusions (due to a porous object)
Preheat the work piece (before application) to temperature just above the stoving temperature.
Water on the work piece
Check the drier and the work piece hangers.
Bubbles in
the film
Powder film too thick (TGIC free powder IPDI)
Decrease film.
Poor impact resistance or poor flexibility
Poor cleaning or pretreatment
Check the pretreatment equipment and chemicals.
Under-cured film
Increase oven temperature or stoving time.
Coating thickness too high
Reduce the thickness by lowering voltage or reducing spray time.
Off Color
Improper oven exhaust
Check the exhaust vent fans.
Bake time is too long or too short
Adjust the conveyor speed or oven temperature.
Oven temperature is too high or too low
Adjust oven temperature.
Orange Peel
Warm-up of the coated material too slow or too fast
Check the curing cycle and curing oven.
Film thickness too low
Poor corrosion resistance
Increase the thickness by raising voltage or increasing spray time.
Replace the powder.
Heat damage to powder
Under-cured film
Increase oven temperature or stoving time.
Poor cleaning or treatment
Check the pretreatment equipment and chemicals.
Poor pencil hardness or poor abrasion resistance
Under-cured film
Increase oven temperature or stoving time.
Poor adhesion
Poor cleaning or pretreatment
Check the pretreatment equipment and chemicals.
Under-cured film
Increase oven temperature or stoving time.
Coating thickness to high
Reduce the thickness by lowering voltage or reducing spray time.
