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© 2020. Manifa Powder Coatings.  Created by Haron Didaagun

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.