General Tips
Troubleshooting
General Tips
Coating defects, gloss and appearance, mechanical, chemical, application.
Powder Supply, Hoses, Pumps and Venturis
Contamination of Substrate of Powder
Powder Coating Application
Poor attraction of powder to the component
CAUSE
SOLUTION
Incorrect voltage at the gun
Check voltage, clean or replace gun
Poor earthing
Clean grounding points & hangers
Excessive build up of cured powder coating on hangers
Clean hangers
Moisture in spray booth
Check booth air supply for quality
Gun air pressure too high
Reduce forward air pressure
Incorrectly positioned guns
Reposition offending guns
Poor hanger design
Re-design hangers to reduce shielding
Poor penetration
CAUSE
SOLUTION
Too low powder delivery
Increase powder flow
Poor grounding
Check & improve grounding
Incorrect spray pattern
Try different spray nozzles
Too high voltage
Reduce voltage so that surfaces closest to the gun do not repel powder
Incorrect powder delivery velocity
Reduce air setting so powder air stream does not blow powder away
Poor gun placement
Adjust gun position to enter more directly into recessed area
Powder too fine
Reduce ratio of reclaim to hopper or Check particle size distribution
Film thickness on component too low
CAUSE
SOLUTION
Powder delivery rate insufficient
Set correct powder flow pressure or Check if venturi is the right size, clean and set correctly
Insufficient coating time
Increase coating time of component by slowing the conveyor speed or Increase voltage and forward air flow, reposition guns
Faraday cage effect
Adjust voltage and forward air flow, reposition guns
Surface area of hanger too large compared to the surface area of the workpiece
Reduce the size of hangers
Damp powder
Remove powder and replace, ensure powders are sealed and stored in the correct manner
Appearance looks uneven & broken before curing
CAUSE
SOLUTION
Back ionisation
Reduce Voltage
or
Check if earthing points are clean
or
Reduce deposition rate and film thickness
or
Ensure no moisture is entering the system
or
Move gun further away from component
or
Check for build up of metallic particles within the gun and components, clean if necessary
Film thickness on component to high
CAUSE
SOLUTION
Excessive powder delivery
Reduce powder feed to gun
or
Increase distance between gun and component
Gun voltage to high
Reset gun voltage
Excessive coating duration
Reduce time of component in front of the gun by: Increasing the conveyor speed
or
Increase the reciprocator speed
Surging and spitting
CAUSE
SOLUTION
Damp air supply
Check air drier
or
Install refrigeration unit
or
Empty water taps
Varying air supply
Possible compressor overload
Damp powder
Remove powder, full plant clean down, start again with new powder. Ensure any remaining powder is resealed securely until re-use
Powder too fine
Check ratio of recovered powder to virgin powder is correct. Alter if require
Recovery and Reclaim
Poor containment of powder booth
CAUSE
SOLUTION
Primary air-filters blocked or damaged
Set correct powder flow pressure
or
Check if venturi is the right size, clean and set correctly
Secondary air-filters overloaded due to damage of main filters
Increase coating time of component by slowing the conveyor speed
or
Increase voltage and forward air flow, reposition guns
Spray booth opening too large
Adjust voltage and forward air flow, reposition guns
Improper gun position
Reduce the size of hangers
Powder delivery too high
Remove powder and replace, ensure powders are sealed and stored in the correct manner
Contamination of surface of work-piece
CAUSE
SOLUTION
Powder or foreign particles falling from conveyor or hangers
Clean conveyor regularly and strip hangers / hooks
Contamination through reclaim powder, damage to the in-line sieve
Replace torn sieve
Contamination through foreign bodies from work floor entering booth
Clean work floor and improve house keeping
Contamination through compressed air supply
Check compressed air for quality
Contamination by recycled powder
CAUSE
SOLUTION
Ineffective cleaning of recovery and recycle system
Complete clean down of system
Powder recovery below specified rate
CAUSE
SOLUTION
Air velocity too low
Compare air flow with specification
Powder too fine
Check PSD of powder, contact the powder manufacturer
Curing of Powder
Gloss too high
CAUSE
SOLUTION
Cure temperature too low
Increase air temperature and metal temperature
or
Decrease track line speed
Oven cycle too short
Decrease track line speed
or
Increase oven temperature
or
Extend cure time (box oven)
Gloss too low
CAUSE
SOLUTION
Oven temperature too high
Reduce air temperature and check metal temp
or
Increase line speed
Time in the oven too long
Increase line speed
or
Decrease oven temp
Contamination with a powder which is incompatible
Clean all equipment including guns, booth and recovery system and re-charge with virgin powder
Contamination with solven which may contain chlorinated hydrocarbons
Check proximity of vapour degreasing plant; restrict air movement to the powder coating application area
Poor flow
CAUSE
SOLUTION
Heat up rate of the metal too slow
Increase the temperature at the first stage of the oven
Poor hammer or texture development
CAUSE
SOLUTION
Heat up rate too slow
Increase the temperature at the first stage of the oven
Too much reclaim
Reduce the amount of reclaim with the addition of virgin powder
Poor adhesion
CAUSE
SOLUTION
Under cure film
Increase oven temperature
or
Decrease line speed
Poor pretreatment
Check pre-treatment, adjusting tanks in line with supplier recommendation
Even discolouration
CAUSE
SOLUTION
Cure temperature too high
Reduce oven temperature or increase line speed
Patchy discolouration
CAUSE
SOLUTION
Corrosion products on the metal surface
Increase line speed
or
Decrease oven temp
Inadequate pre-treatments
Reduce air temperature and check metal temp
or
Increase line speed
Powder contamination
Check cleanliness of plant and recycling system
Powder supply, hoses, pumps & venturis
Poor fluidisation in powder hopper
CAUSE
SOLUTION
Powder level too low
Add powder to the normal level
Compact or damp powder
Manually loosen powder in hopper
or
Check compressed air for quality
Partly plugged membrane
Check bottom of hopper and membrane for any obstruction
Powder particle size
Decrease the amount of reclaim to the hopper
or
Check PSD of virgin powder
Blocked hoses powder pump or venturi
CAUSE
SOLUTION
Normal build up
Clean or replace parts
Too high air pressure
Reduced air pressure on pump and gun
Air supply moist
Check air supply for quality
Material choice of hose
Check hoses for material quality
Powder hoses too long
Modify layout or shorten hose
Worn venturi or pump
Replace worn parts
Too fine powder
Decrease amount of reclaim powder to hopper
or
Check PSD of virgin powder
Powder dusting out of hopper
CAUSE
SOLUTION
Too high air pressure
Reduce air pressure too the fluid bed
Too fine powder
Decrease amount of reclaim to hopper
or
Check PSD of virgin powder
Contamination of substrate of powder
Foreign matter in film
CAUSE
SOLUTION
Inadequate cleaning
Check or adjust flow rate, spray nozzle position and temp in each pre-treatment stage
or
Check or adjust operating specs for chemicals
or
Clean guns booths and recovery systems
Powder is too course or not sieved
Sieve all reclaim powder, check for holes in sieve,check or change sieve mesh size
Virgin powder is bitty
Talk to your lab
Chemical cross-contamination
CAUSE
SOLUTION
Improper loading or spacing of parts
Check and adjust parts for maximum drainage
or
Check and adjust drain time between stages
Contamination of colour
CAUSE
SOLUTION
Cross contamination from manufacturer
Contact lab
Poor housekeeping when colour changing
Totally clean plant, gun and recycling equipment and recharge with new powder
Pinholes in the film
CAUSE
SOLUTION
Oil / water in the air supply
Check oil / water seperators on the air supply
Oil contamination
Check degreasing plant
Silicone contamination
Locate and remove source