1. Problems during the application 1.1 Fluidisation ... - BASF Coatings
1. Problems during the application 1.1 Fluidisation ... - BASF Coatings
1. Problems during the application 1.1 Fluidisation ... - BASF Coatings
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<strong>1.</strong> <strong>Problems</strong> <strong>during</strong> <strong>the</strong> <strong>application</strong><br />
<strong>1.</strong>1 <strong>Fluidisation</strong><br />
Detection Possible cause Remedy<br />
Intermittent output or no<br />
output at all from gun<br />
Visible local blistering and<br />
pinholing in fluid hopper<br />
Deficient flowability in<br />
powder circulation<br />
Fluidising air too low<br />
Fluidising plate clogged<br />
Grain size distribution<br />
Compressed air too moist, oily<br />
Moist powder coating<br />
Relative air humidity in room for<br />
powder coating <strong>application</strong><br />
Fluidising plate clogged or damaged<br />
Too strong refinement of powder<br />
coating material<br />
Air temperature in coating units too<br />
high<br />
„Lumps“ in fluidised powder coating<br />
material<br />
Increase fluidising air pressure<br />
Check fluidising plate<br />
Check grain size distribution<br />
Fine fraction<br />
Check function of refrigeration<br />
dryer for compressed air<br />
Check oil-water separator<br />
Clean or replace fluidising plate<br />
Check grain size range, observe<br />
metered addition of fresh powder<br />
coating material<br />
Observe storage conditions of<br />
powder coating manufacturer<br />
Inform powder coating<br />
manufacturer<br />
Have lumping checked<br />
Empty hopper<br />
Insufficient separation rate Provide for functioning circulation<br />
Check charging of powder coating<br />
material (recovery, filter)
<strong>Problems</strong> <strong>during</strong> <strong>the</strong> <strong>application</strong><br />
<strong>1.</strong>2. Deposits, sintering in hoses and injectors<br />
Detection Possible cause Remedy<br />
Irregular powder discharge<br />
from <strong>the</strong> gun (intermittent,<br />
powder lumps, powder<br />
spitting)<br />
Air speed too high<br />
Powder discharge too high<br />
Wrong gun attachment<br />
Hose unsuitable (hose material,<br />
installation, dimensions)<br />
Reduce air speed<br />
Distribute powder discharge to<br />
more guns<br />
Use suitable guns or gun<br />
attachments<br />
Use suitable hoses, observe hose<br />
installation and hose length
<strong>Problems</strong> <strong>during</strong> <strong>the</strong> <strong>application</strong><br />
<strong>1.</strong>3. Deposits, sintering on spraying devices (deflector plates, nozzles)<br />
Detection Possible causes Remedy<br />
Mechanically damaged or worn parts<br />
Powder in circulation too fine<br />
Metered addition of new powder to<br />
circulation insufficient<br />
Humidity in powder coating material<br />
too high<br />
Feed air pressure too high<br />
Pressure fluctuations in compressed<br />
air system<br />
Clean injectors, deflector plates<br />
and nozzles such that surfaces are<br />
nei<strong>the</strong>r roughened nor get<br />
damaged<br />
Continually meter and add new<br />
powder automatically<br />
Check function of refrigeration<br />
dryer and oil-water separators<br />
Reduce feed air pressure<br />
Check compressed fair system
<strong>Problems</strong> <strong>during</strong> <strong>the</strong> <strong>application</strong><br />
<strong>1.</strong>4. Irregular film thickness distribution on object<br />
Detection Possible causes Remedy<br />
Colour changes caused by<br />
opacity differences<br />
(streaking) of powder coating<br />
film<br />
Surface does not look<br />
uniform<br />
Irregular powder output, distance<br />
between gun and object not ideal<br />
Relation between belt speed and<br />
stroke speed of guns not ideal; high<br />
voltage fluctuations<br />
Grain size distribution not ideal<br />
Object design (Faraday cage) and/or<br />
suspension unfavourable<br />
Feed fair pressure too high<br />
Powder coating film is blown off<br />
because fair speed is too high<br />
Optimise system parameters<br />
Optimise grain size distribution<br />
Change object design and/or<br />
suspension<br />
Reduce delivery pressure
<strong>Problems</strong> <strong>during</strong> <strong>the</strong> <strong>application</strong><br />
<strong>1.</strong>5. Adhesion of powder coating is insufficient (powder coating material flows off) on flat objects<br />
Detection Possible causes Remedy<br />
Colour changes caused by<br />
opacity differences of<br />
powder coating film; surface<br />
does not look uniform<br />
Insufficient grounding of objects, field<br />
strength too high<br />
Metering air or atomised air not ideal<br />
Voltage too high<br />
Powder discharge too high<br />
Optimise system parameters, clean<br />
suspension gear<br />
Change voltage and distance<br />
between guns and object<br />
Reduce voltage<br />
Reduce powder discharge<br />
Grain size distribution not ideal Inform powder coating<br />
manufacturer
<strong>Problems</strong> <strong>during</strong> <strong>the</strong> <strong>application</strong><br />
<strong>1.</strong>6. On objects with corners and recesses (powder coating material is blown off)<br />
Detection Possible causes Remedy<br />
Parts of <strong>the</strong> object remain<br />
uncoated<br />
Hose material unsuitable<br />
Wrong gun attachment<br />
Feed fair speed in gun too high<br />
Geometry of object or suspension<br />
unfavourable for coating<br />
Use suitable hose material<br />
Use suitable gun attachment<br />
Reduce feeding fair speed<br />
Change object design and/or<br />
suspension
for TRIBO <strong>application</strong><br />
Detection Possible causes Remedy<br />
See above Insufficient charging due to:<br />
• Excessive powder flow rate<br />
• Wrong grain size distribution<br />
• Worn detectors in gun<br />
Permanently measure leakage<br />
current or specific TRIBO charging<br />
of powder coating material
<strong>Problems</strong> <strong>during</strong> <strong>the</strong> <strong>application</strong><br />
<strong>1.</strong>7 Film formation on edges<br />
Detection Possible causes Remedy<br />
Distinct formation of beads<br />
on objects' corners and<br />
edges<br />
Distinct formation of beads<br />
on objects' corners and<br />
edges<br />
Powder cloud too large<br />
Distances between objects too large<br />
(shield edges)<br />
Content of coarse particles in<br />
powder coating material too high<br />
Change <strong>the</strong> powder cloud<br />
systematically<br />
Deactivate powder delivery<br />
between gaps (use gap control)<br />
Optimise grain size distribution
<strong>Problems</strong> <strong>during</strong> <strong>the</strong> <strong>application</strong><br />
<strong>1.</strong>8 Picture frame effect<br />
Detection Possible causes Remedy<br />
Surface does not look<br />
uniform, edge area differs<br />
Varying separation behaviour on<br />
objects’s surface<br />
Powder discharge too high, voltage<br />
too high<br />
Unfavourable distance between guns<br />
and object<br />
Use suitable guns or gun<br />
attachments<br />
Reduce delivery pressure and high<br />
voltage<br />
Contact coating unit manufacturer,<br />
supplier
<strong>Problems</strong> <strong>during</strong> <strong>the</strong> <strong>application</strong><br />
<strong>1.</strong>9 Sudden emergence of powder from spray booth<br />
Detection Possible cause Remedy<br />
Powder coating material<br />
escapes from booth and<br />
contaminates vicinity<br />
Most frequent causes are draughts<br />
in factory halls due to open windows<br />
and doors<br />
Filter material in recovery unit<br />
„clogged“<br />
Close windows and doors<br />
Check filter’s negative pressure
<strong>Problems</strong> <strong>during</strong> <strong>the</strong> <strong>application</strong><br />
<strong>1.</strong>10 Discharges<br />
Detection Possible cause Remedy<br />
Spark formation Insufficiently conductive hose<br />
material<br />
Objects insufficiently grounded<br />
Electric shock to humans Insufficient grounding of manual gun<br />
Use hoses recommended by<br />
coating unit supplier<br />
Clean suspension hooks<br />
Remove paint from suspension<br />
gear regularly<br />
Grounding cable<br />
Observe cross section<br />
Use of metallic powder Use suitable gun attachment<br />
Wear conductive protective<br />
clothing (shoes)
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