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In cases where spray coating is unsatisfactory, the reasons for appearance defects may be complex
and can be a combination of several factors.
1. Poor atomization
Possible causes
Solution
(1) Too low atomization air pressure
(1) Increase pressure.
(2) Too high paint output
(2) Decrease output or increase atomizing air
pressure
(3) Too high a viscosity
(3) Lower the viscosity with solvent
(4) Nozzle electrode pin is bent.
(4) Straighten or replace the pin.
(5) Nozzle is damaged
(5) Repair or replace it.
(6) Solvent is not adequate
(6) Consult material supplier.
(7) Improper adjustment of nozzle air
guide (However, only round spray
nozzle HN54SA)
(7) Adjust the clearance with the air guide to
0.2mm. (one turn: 1mm)
2. Too much paint bouncing back
Possible causes
Solution
(1) Too long spray distance
(1) Keep the distance at 150 to 200mm.
(2) Too high atomizing air pressure
(2) Lower the pressure.
(3) Too low paint resistance value
(3) Adjust the resistance to 15 to 70M ohm-cm.
(4) Insufficient grounding of object
(4) Secure the grounding.
(5) Too low air exhausting speed
(5) Increase the exhaust fan speed.
3. Poor transfer efficiency
Possible causes
Solutions
(1) Inferior grounding of object
(1) Clean hangers
(2) Too high atomizing air pressure
(2) Adjust the pressure to an adequate level.
(3) Too far spray distance
(3) Keep the distance at 150 to 200mm.
(4) Too low charging voltage
(4) Increase high voltage output by adjusting
switch on control unit
(5) Too high air exhausting speed
(5) Slow the exhaust fan speed.
(6) Too high paint resistance value
(6) Adjust the resistance to 15 to 70M ohm-cm.
11
Trouble shooting on spray technique
