This page is a simple guide that may help you trouble shoot common powder coating problems. You can scroll through the page or choose what your problem may be and it will take you to that section.
Application Problems
Poor Fluidization
Poor Powder Containment
Poor Spray Pattern
Powder Feed
Blocked Hoses/Powder Pumps
Reclaim Equipment
Poor Charging
Poor Penetration
Back Ionization
Film Properties Problems
Poor Flow
Gloss too Low
Gloss too High
Contamination
Film Thickness
Color
Pinholing
Bare Edges/Areas
Film Aspect
Poor Mechanicals
Adhesion
Chemical Resistance
Surface Hardness
APPLICATION PROBLEMS
PROBLEM |
POSSIBLE CAUSE |
SOLUTIONS
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POOR FLUIDIZATION |
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Air blowing large holes through powder surface |
Powder level too low |
· Add powder until feed hopper is filled to proper level
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Packed or moist powder |
· Manually loosen powder and fluidize with clean dry air · Check compressed air for oil/water and room for high humidity
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Obstructed membrane |
· Check bottom of feed hopper for obstructions/oil/water.
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Powder particle size |
· Maintain consistent ratio of virgin to reclaim
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Powder blowing out of hopper |
Fluidizing air pressure too high |
· Reduce air pressure to fluid bed
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Insufficient hopper ventilation |
· Check hopper vent for blockage · Check vents assist for obstructions and correct air supply
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Powder too fine |
· Reduce the amount of reclaim added to virgin powder
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No air percolation through to powder surface |
Insufficient air pressure |
· Increase air supply to fluid bed
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Blocked membrane |
· Clean membrane;remove any dirt, grease and obstructions. Check air supply to ensure it is
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Obstructed membrane |
· Remove all obstructions on the membrane
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Compacted powder on membrane |
· Manually loosen powder and fluidize with clean dry air
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BACK TO TOP
POOR POWDER CONTAINMENT |
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Inadequate air flow through spray booth |
Primary filter media blocked |
· Clean filter system. Replace filter if necessary · Check ambient air for excessive moisture · Check filter air pulse system for correct operation
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Final filter blocked |
· Check primary filters for powder leakage. Service or replace if necessary
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Use of compressed air for booth clean down |
· Refer to operating manual for correct cleaning methods
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Improper powder gun placement/alignment |
· Correct as necessary. Position guns away from booth opening · Check for proper distance from top of part to the conveyor slot opening
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Room air drafts causing powder to drift from booth |
· Correct as necessary. Position guns away from booth opening · Check for proper distance from top of part to the conveyor slot opening
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Blocked airflow |
· Check air volume control damper adjustments
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POOR SPRAY PATTERN |
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Non-symmetrical powder cloud |
Worn gun parts |
· Replace parts as required
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Impact fusion build-up |
· Check gun parts as required
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Delivery air too low |
· Check air supply. Increase air for powder feed
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Hoses, powder pumps or guns blocked with powder |
· Clean hoses, pumps and guns
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Reciprocator speed too fast |
· Adjust gun cycle time
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BACK TO TOPPOWDER FEED |
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Powder feed surging or spitting. Interrupted powder flow |
Insufficient air pressure or volume |
· Check compressed air supply. Mains air pressure should be a minimum of 80 PSI and
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Hoses kinked, flattened or too long |
· Check all powder and air feed lines, straighten and shorten if necessary
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Hoses, powder pumps or suction pumps |
· Clean hoses, powder pumps and gun components · Check air supply for moisture and oil contaminants · Check powder delivery and dilution air settings · Check coating area, relative humidity and temperature · Check powder delivery system for leaks check powder delivery hose size for powder
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Incorrect feed hopper fluidization |
· Adjust fluidization air pressure · Check fluidization membrane for damage, oil or water contamination · Check for moisture or oil in the powder
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Low powder level |
· Add powder to the proper level in the hopper
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BACK TO TOPBLOCKED HOSES/POWDER PUMPS |
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Caused by impact fusion build-up |
Air pressure too high |
· Clean or replace worn parts in pump · Reduce powder hose length · Decrease flow rate settings on pumps
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Moisture in compressed air |
· Check air supply filters/dryers to clean, dry oil-free compressed air
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Worn powder pumps or parts |
· Replace all worn or damaged parts
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BACK TO TOPRECLAIM EQUIPMENT |
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Contamination in reclaim powder |
· Reclaim in-line sieve torn · Powder or dirt falling in spray booth from conveyors, jigs, or flight bars |
· Repair sieve or replace, if necessary · Clean conveyor regularly before it enters powder booth · Strip jigs regularly
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Contamination from components entering booth |
· Check cleaning and pre-treatment system · Ensure components are clean and dry before entering booth
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Contamination from plant air circulated through spray booth |
· Isolate and preferable enclose spray booth area · Keep outside doors closed · Maintain positive air pressure in coating room · Do not use silicone based oils or lubricants · Do not use aerosol sprays containing oil in the booth area
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Powder levels in booth too high |
Bag or cartridge filters blinding |
· Clean or replace bags or cartridge filters · Check spray booth humidity · Check reverse air cleaning
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Too large an open area in spray booth housing |
· Reduce open area. Increased opening reduce booth air velocity
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Powder delivery rates too high |
· Reduce the number of guns spraying or the amount of powder to each gun
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BACK TO TOPPOOR CHARGING |
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Inadequate powder film thickness, poor coverage |
High voltage is not providing enough kV at charging electrode |
· Check if high voltage is ON. Systematically check electrical continuity from the · Use kV meter and megohmmeter to check condition of multiplier, cable/resistor. · Clean/replace electrode insulated or damaged by powder build-up or impact fusion
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Poor earthing |
· Checking earthing from conveyor rail through hanger to part. Contact areas must be
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Powder delivery too high |
· Reduce powder feed until material is adequately charged |
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Excessive moisture in air supply |
· The charge can be dissipated by moist air, humidity must be controlled
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Powder too fine |
· Maintain consistent ratio of virgin to reclaim 3:1 · Check particle size of virgin powder
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Powder delivery air too high. Powder blowing past component |
· Turn down air setting or move gun position further away from component
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BACK TO TOPPOOR PENETRATION |
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Powder will not coat Faraday Cage area (holes, grooves, channels, inside corners or |
Powder delivery too low |
· Increase powder flow rate air setting · Replace all worn or damaged parts
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Poor earthing |
· Check all earthing point contacts. Clean if necessary
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Incorrect spray pattern or nozzle |
· Adjust spray pattern or select a more suitable nozzle, i.e. flat-spray, deflector or
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Poor gun placement |
· Adjust gun position so powder cloud has a direct path to recess area
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Voltage too high |
· Decrease voltage level
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Powder delivery velocity too high |
· Decrease voltage level
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Powder delivery velocity too high |
· Decrease flow rate and/or atomizing settings so powder air stream does not blow out of |
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BACK TO TOPBACK IONIZATION |
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Powder layers are repelled from components |
Voltage too high |
· Decrease voltage level |
Gun position too close to component |
· Move gun further away from component |
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Poor earthing |
· Check all earthing point contacts. Clean if necessary |
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Excessive heavy powder build up |
· Decrease powder supply to gun · Increase conveyor speed · Move gun further away from component
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Film Properties Problems
PROBLEM |
POSSIBLE CAUSE |
SOLUTIONS |
POOR FLUIDIZATION |
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Too much orange peel |
Film thickness too low/high |
· Increase/decrease film thickness by adjusting application equipment |
Oven temperature too low |
· Set oven to correct temperature |
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Heat up rate too slow |
· Modify oven baffling heat rate at front of oven |
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Back Ionization |
· See application section Back Ionization above |
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BACK TO TOPGLOSS TOO LOW |
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Too low for high gloss powder |
Incompatible powder contamination |
· Clean application equipment before changing powders |
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Micropinholing from gassing |
· Check component for porosity · Check component for moisture · Check powder for moisture from reclaim or compressed air · Check film thickness, coating too thick |
BACK TO TOPGLOSS TOO HIGH |
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Too high for low gloss powder |
Undercured |
· Check burners, isolate oven · Increase dwell time in oven |
BACK TO TOPCONTAMINATION |
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Contamination in powder |
Reclaim in-line sieve torn |
· Repair sieve or replace if necessary |
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Contamination from plant air circulated through spray booth |
· Isolate and preferably enclose spray booth area |
FILM THICKNESS |
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BACK TO TOP |
Inconsistent film thickness |
Guns positioned incorrectly |
· Check and reposition guns |
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Reciprocators not matched to line speed |
· Adjust line speed · Adjust reciprocator stroke |
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Air speed in booth disturbing spray pattern |
· Consult your equipment supplier |
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Defective spray equipment |
· Consult your equipment supplier |
BACK TO TOPCOLOR |
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Off shade |
Stoving time too long |
· Adjust line speed |
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Oven temperature too high |
· Decrease oven temperature |
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Variation in film thickness |
· See Cured Film section Film Thickness above |
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Foul oven air |
· Check has supply, burners and venting |
BACK TO TOPPINHOLING |
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Pin holding and gassing through coating surface |
Occur during curing as gasses that are trapped escape through the powder
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Check cleanliness of the part Prebaking may help solve this Cleaning the lines and checking for oil |
BACK TO TOPBARE EDGES/AREAS |
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Pin holding and gassing through coating surface |
Uncharged powder |
· See Application section Poor Charging · Check pretreatment equipment, dry-off oven and part drainage |
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Poor cleaning, metal preparation or dry-off |
· See Application section Poor Charging · Check pretreatment equipment, dry-off oven and part drainage |
BACK TO TOPFILM ASPECT |
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Texture pattern or metallic effect incorrect |
Poor powder charging |
· See Application section Poor Charging |
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Poor earth |
· See Application section Poor Charging |
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Guns too close or distant from component |
· Adjust distance |
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Separation in hopper |
· See Poor Fluidization section |
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Powder delivery too high |
· Adjust |
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Film thickness too high or low |
· Adjust |
BACK TO TOPPOOR MECHANICALS |
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Poor impact resistance, poor flexibility |
Undercured |
· Increased oven temperature · Increased dwell time in oven |
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Poor cleaning or pretreatment |
· Check pretreatment equipment and chemicals |
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Film thickness too high |
· Reduce film thickness by adjusting application equipment |
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Change in substrate thickness or type |
· Check substrate with supplier |
BACK TO TOPADHESION |
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Poor adhesion |
Poor cleaning or pretreatment |
· Check pretreatment equipment and chemicals |
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Change in substrate thickness or type |
· Check substrate with supplier |
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Undercured |
· Increase oven temperature · Increase dwell time in oven |
BACK TO TOPCHEMICAL RESISTANCE |
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Poor chemical resistance |
Undercured |
· Increase oven temperature · Increase dwell time in oven |
BACK TO TOPSURFACE HARDNESS |
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Poor pencil hardness, poor abrasion resistance |
Undercured |
· Increase oven temperature · Increase dwell time in oven |
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Undercured |
· Reduce oven temperature |
BACK TO TOP