Trouble Shooting Guide

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

 

POOR FLUIDIZATION

Air blowing large holes through powder surface

Powder level too low

· Add powder until feed hopper is filled to proper level

 

Packed or moist powder

· Manually loosen powder and fluidize with clean dry air

· Check compressed air for oil/water and room for high humidity

 

Obstructed membrane

· Check bottom of feed hopper for obstructions/oil/water.

 

Powder particle size

· Maintain consistent ratio of virgin to reclaim

 

Powder blowing out of hopper

Fluidizing air pressure too high

· Reduce air pressure to fluid bed

 

Insufficient hopper ventilation

· Check hopper vent for blockage

· Check vents assist for obstructions and correct air supply

 

Powder too fine

· Reduce the amount of reclaim added to virgin powder

 

No air percolation through to powder surface

Insufficient air pressure

· Increase air supply to fluid bed

 

Blocked membrane

· Clean membrane;remove any dirt, grease and obstructions. Check air supply to ensure it is
clean

 

Obstructed membrane

· Remove all obstructions on the membrane

 

Compacted powder on membrane

· Manually loosen powder and fluidize with clean dry air

 

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POOR POWDER CONTAINMENT

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

 

Final filter blocked

· Check primary filters for powder leakage. Service or replace if necessary

 

Use of compressed air for booth clean down

· Refer to operating manual for correct cleaning methods

 

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

 

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

 

Blocked airflow

· Check air volume control damper adjustments

 

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POOR SPRAY PATTERN

Non-symmetrical powder cloud

Worn gun parts

· Replace parts as required

 

Impact fusion build-up

· Check gun parts as required

 

Delivery air too low

· Check air supply. Increase air for powder feed

 

Hoses, powder pumps or guns blocked with powder

· Clean hoses, pumps and guns

 

Reciprocator speed too fast

· Adjust gun cycle time

 

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POWDER FEED

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
of sufficient volume to supply the system

 

Hoses kinked, flattened or too long

· Check all powder and air feed lines, straighten and shorten if necessary

 

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
flow

 

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

 

Low powder level

· Add powder to the proper level in the hopper

 

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BLOCKED HOSES/POWDER PUMPS

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

 

Moisture in compressed air

· Check air supply filters/dryers to clean, dry oil-free compressed air

 

Worn powder pumps or parts

· Replace all worn or damaged parts

 

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RECLAIM EQUIPMENT

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

 

Contamination from components entering booth

· Check cleaning and pre-treatment system

· Ensure components are clean and dry before entering booth

 

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

 

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

 

Too large an open area in spray booth housing

· Reduce open area. Increased opening reduce booth air velocity

 

Powder delivery rates too high

· Reduce the number of guns spraying or the amount of powder to each gun

 

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POOR CHARGING

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
voltage source to electrode, including the cable, resistor and fuses.

· 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

 

Poor earthing

· Checking earthing from conveyor rail through hanger to part. Contact areas must be
free of powder build-up, grease and other insulators

 

Powder delivery too high

· Reduce powder feed until material is adequately charged

Excessive moisture in air supply

· The charge can be dissipated by moist air, humidity must be controlled

 

Powder too fine

· Maintain consistent ratio of virgin to reclaim 3:1

· Check particle size of virgin powder

 

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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POOR PENETRATION

Powder will not coat Faraday Cage area (holes, grooves, channels, inside corners or
recesses)

Powder delivery too low

· Increase powder flow rate air setting

· Replace all worn or damaged parts

 

Poor earthing

· Check all earthing point contacts. Clean if necessary

 

Incorrect spray pattern or nozzle

· Adjust spray pattern or select a more suitable nozzle, i.e. flat-spray, deflector or
pin-point

 

Poor gun placement

· Adjust gun position so powder cloud has a direct path to recess area

 

Voltage too high

· Decrease voltage level

 

Powder delivery velocity too high

· Decrease voltage level

 

Powder delivery velocity too high

· Decrease flow rate and/or atomizing settings so powder air stream does not blow out of
corners

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BACK IONIZATION

Powder layers are repelled from components

Voltage too high

· Decrease voltage level

Gun position too close to component

· Move gun further away from component

Poor earthing

· Check all earthing point contacts. Clean if necessary

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

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

Heat up rate too slow

· Modify oven baffling heat rate at front of oven

Back Ionization

· See application section Back Ionization above

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GLOSS TOO LOW

Too low for high gloss powder

Incompatible powder contamination

· Clean application equipment before changing powders

 

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

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GLOSS TOO HIGH

Too high for low gloss powder

Undercured

· Check burners, isolate oven

· Increase dwell time in oven

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CONTAMINATION

Contamination in powder

Reclaim in-line sieve torn

· Repair sieve or replace if necessary

 

Contamination from plant air circulated through spray booth

· Isolate and preferably enclose spray booth area

 

FILM THICKNESS

 

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Inconsistent film thickness

Guns positioned incorrectly

· Check and reposition guns

 

Reciprocators not matched to line speed

· Adjust line speed

· Adjust reciprocator stroke

 

Air speed in booth disturbing spray pattern

· Consult your equipment supplier

 

Defective spray equipment

· Consult your equipment supplier

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COLOR

Off shade

Stoving time too long

· Adjust line speed

 

Oven temperature too high

· Decrease oven temperature

 

Variation in film thickness

· See Cured Film section Film Thickness above

 

Foul oven air

· Check has supply, burners and venting

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PINHOLING

Pin holding and gassing through coating surface

Occur during curing as gasses that are trapped escape through the powder

 

 

Check cleanliness of the part Prebaking may help solve this Cleaning the lines and checking for oil

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BARE EDGES/AREAS

Pin holding and gassing through coating surface

Uncharged powder

· See Application section Poor Charging

· Check pretreatment equipment, dry-off oven and part drainage

 

Poor cleaning, metal preparation or dry-off

· See Application section Poor Charging

· Check pretreatment equipment, dry-off oven and part drainage

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FILM ASPECT

Texture pattern or metallic effect incorrect

Poor powder charging

· See Application section Poor Charging

 

Poor earth

· See Application section Poor Charging

 

Guns too close or distant from component

· Adjust distance

 

Separation in hopper

· See Poor Fluidization section

 

Powder delivery too high

· Adjust

 

Film thickness too high or low

· Adjust

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POOR MECHANICALS

Poor impact resistance, poor flexibility

Undercured

· Increased oven temperature

· Increased dwell time in oven

 

Poor cleaning or pretreatment

· Check pretreatment equipment and chemicals

 

Film thickness too high

· Reduce film thickness by adjusting application equipment

 

Change in substrate thickness or type

· Check substrate with supplier

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ADHESION

Poor adhesion

Poor cleaning or pretreatment

· Check pretreatment equipment and chemicals

 

Change in substrate thickness or type

· Check substrate with supplier

 

Undercured

· Increase oven temperature

· Increase dwell time in oven

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CHEMICAL RESISTANCE

Poor chemical resistance

Undercured

· Increase oven temperature

· Increase dwell time in oven

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SURFACE HARDNESS

Poor pencil hardness, poor abrasion resistance

Undercured

· Increase oven temperature

· Increase dwell time in oven

 

Undercured

· Reduce oven temperature

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