Corona Charging VS Tribo spray

andrewfei

To guide your decision whether to select a Corona or a
Tribo application method, listed below are the
advantages and disadvantages of both:
Corona Charging:
Advantages
1) Strong electrostatic field results in effective
charging and higher deposition
2) Electrostatic fieldlines support the powder
particles to move towards the work-piece
3) Simple repairs of the powdered surface are
possible
4) Light, robust spray gun
5) Accepts different types of powder materials and
particle sizes
6) Film thickness can be simply changed by voltage
variations
7) Simple construction is suited for fast colour
changes.
Disadvantages
1) Redundant ions generate a self-limiting effect
2) Strong fieldlines lead to Faraday effect (irregular
coating, corners and crevices are not properly
covered)
3) These effects can be reduced or eliminated
respectively by voltage changes or use of antiionisation
rings (to reduce Faraday and Orange
peel effect).
Tribo Spray:
Advantages
1) No Faraday effect; deep crevices, corners and
hollow spaces can be better penetrated
2) Powder can be better directed by the use of
directional finger sprayers and aerodynamics
3) Less, if any, fatty edges on the coated surface
4) Uniform coating
5) Very good automation possibilities
6) Higher charging effect without high voltage
generator
7) Higher deposition effect
8) Higher productivity by closer arrangement of
objects
9) More optimal film thickness build-up
10) Better flow; practically no orange peel effect
11) Reduced risk for back-ionisation
12) Lower powder consumption
Disadvantages
1) Performance is strongly influenced by
uncontrolled air-streams
2) Special powder is necessary; formulation must be
adapted to the Tribo charging process
3) Particles smaller than 10 microns are difficult to
charge
4) Charging of particles takes more time and
efficiency reduces during long runs
5) Colour changes take a long time
6) Higher investment cost for equal capacity output
7) More wear and so shorter life time of gun
internals and other parts such as powder pump
venturi inserts
8) More precise specifications for the cleanliness and
humidity of the compressed air
9) Comprehensive training of the application
personnel is recommended.
Note: Industries using the tribo method of application
are usually in Northern Europe where the humidity is
more constant and the temperature lower in summer
months.

sunny

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