|
Status
|
Possible causes
|
Possible solutions
|
| 1-Powder blowing out of hopper |
1- air pressure too high
2- Too fine powder particle
|
1- Adjust the pressure
2(I)Too much reclaim added to the virgin powder (should be less that 10%)
2(II)Too fine originally manufactured powder
|
| 2 inadequate air percolation through the powder |
1- Insufficient air pressure
2- plugged membrane
3- compacted powder
4- powder level too high
|
1- check air supply line
2- check the membrane
3- loosen the powder manually
4- Adjust powder level
|
| 3- Powder lumps inside container |
1- powder stored for long time
2- powder stored at conditions differ than requested (temp > 25 c , humidity > 70%)
|
Sieve powder using 250 micron mesh screen |
|
Status
|
Possible cause
|
Possible solutions
|
| 1- Fluctuation in the coating thickness |
1-irregular powder feed
2-inadequate gun distance to the substrate
3- inadequate conveyer speed
4- High-voltage fluctuations
|
1-check powder free flowing properties
2-Readjust the distance between gun and substrate
3- Readjust the conveyer speed
4- Check the electrical continuity from the voltage source to the electrode
|
| 2-Low thickness coat |
1- very low powder feed
2- high speed conveyer
3- large hook size compared to the substrate
4- poor earthing
|
1- adjust air pressure
2- adjust speed of conveyer
3- adjust hook size
4- check earth connections, all contact areas must be free of powder built up , grease or any other insulating
material
|
| 3- poor penetration into recesses and gaps |
1- gun voltage too high
2- powder delivery too low
3-poor earthing
4-inadequate gun position
|
1- turn voltage setting down
2- turn up powder delivery setting
3- check earth connections
4- adjust gun position
|
| 4- Back ionization (powder repelled) |
1- gun voltage too high
2- Gun too close to substrate
|
1- turn voltage setting down
2- adjust gun position
|
|
Status
|
Possible cause
|
Possible solutions
|
| 1-poor impact resistance |
1-under cured film
2-too high film thickness
3-poor pretreatment
|
1-increase oven temperature and/or oven dwell time
2-adjust film application
3-check pretreatment
|
| 2-poor adhesion |
1- poor pretreatment
2- under cured film
|
1- check pretreatment
2- increase oven temperature and/or oven dwell time
|
| 3-decrease in gloss level |
1- powder is contaminated by another type of powder
2-high curing temp
3-high curing time
|
1- in case of changing of powder type or source - even for the same color - all powder line should be thoroughly
cleaned
2- adjust curing temp
3- adjust curing time
|
| 4- increase in gloss level |
1- powder is contaminated by another type of powder
2- grease or oil on substrate surface
3- water or oil in pressurized air
|
1- stop and clean
2-adjust pretreatment
3-check air filters
|
| 5- Cured film easily pealed off substrate |
1- powder is contaminated by another type of powder
2- grease or oil on substrate surface
3- water or oil in pressurized air
|
1- stop and clean
2-adjust pretreatment
3-check air filters
|
| 6-Small holes in film |
1- moisture content of powder or on substrate too high |
1- check powder and substrate humidity condition |
| 7-Poor chemical resistance |
1- under cured film |
1- increase oven temperature |
