Troubleshooting
General tips

Coating defects, gloss and appearance, mechanical, chemical, application.

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

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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

Reduce ratio of reclaim to hopper or check particle size distribution

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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

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

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

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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

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Film thickness on component to high

CAUSE

SOLUTION

Excessive powder delivery

Reduce powder feed to gun
or
Increase distance between gun and component

Reduce powder feed to gun or increase distance between gun and component

Gun voltage to high

Reset gun voltage

Ecessive coating duration

Reduce time of component in front of the gun by: Increasing the conveyor speed
or
Increase the reciprocator speed

Reduce time of component in front of the gun by increasing the conveyor speed or by Increasing the reciprocator speed

Go Up

Surging and spitting

CAUSE

SOLUTION

Damp air supply

Check air drier
or
Install refrigeration unit
or
Empty water taps

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

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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

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

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

Go Up

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

Go Up

Contamination by recycled powder

CAUSE

SOLUTION

Ineffective cleaning of recovery and recycle system

Complete clean down of system

Go Up

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

Go Up

Curing of Powder

Gloss too high

CAUSE

SOLUTION

Cure temperature too low

Increase air temperature and metal temperature
or
Decrease track line speed

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)

Decrease track line speed or increase oven temperature or extend cure time (box oven)

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Gloss too low

CAUSE

SOLUTION

Oven temperature too high

Reduce air temperature and check metal temp
or
Increase line speed

Reduce air temperature and check metal temp or increase line speed

Time in the oven too long

Increase line speed
or
Decrease oven temp

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

Go Up

Poor flow

CAUSE

SOLUTION

Heat up rate of the metal too slow

Increase the temperature at the first stage of the oven

Go Up

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

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Poor adhesion

CAUSE

SOLUTION

Under cure film

Increase oven temperature
or
Decrease line speed

Increase oven temperature or decrease line speed

Poor pretreatment

Check pre-treatment, adjusting tanks in line with supplier recommendation

Go Up

Even discolouration

CAUSE

SOLUTION

Cure temperature too high

Reduce oven temperature or increase line speed

Go Up

Patchy discolouration

CAUSE

SOLUTION

Inadequate pre-treatments

Reduce air temperature and check metal temp
or
Increase line speed

Reduce air temperature and check metal temp or increase line speed

Corrosion products on the metal surface

Increase line speed
or
Decrease oven temp

Increase line speed or decrease oven temp

Powder contamination

Check cleanliness of plant and recycling system

Go Up

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

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

Decrease the amount of reclaim to the hopper or check PSD of virgin powder

Go Up

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

Decrease amount of reclaim powder to hopper or check PSD of virgin powder

Go Up

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

Decrease amount of reclaim to hopper or check PSD of virgin powder

Go Up

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

Go Up

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

Check and adjust parts for maximum drainage or check and adjust drain time between stages

Go Up

Contamination of colour

CAUSE

SOLUTION

Poor housekeeping when colour changing

Totally clean plant, gun and recycling equipment and recharge with new powder

Cross contamination from manufacturer

Contact lab

Go Up

Pinholes in the film

CAUSE

SOLUTION

Silicone contamination

Locate and remove source

Oil contamination

Check degreasing plant

Oil / water in the air supply

Check oil / water seperators on the air supply

Go Up

Troubleshooting General tips