Air Atomization
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Most commonly used for industrial finishing.
- Advantages: Complete pattern control. Finest
atomization.
- Limitations: Uses more air. Creates most
fog. Low transfer efficiency.
- Click here for a diagram
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1.1 Siphon Fed
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Uses vacuum created at nozzle to draw material from
cup. External atomization.
- Advantages: Lowest cost. Less maintenance.
Change colors quickly.
- Limitations: Operator carries weight of material
at gun. Sprays light materials only. One quart maximum.
Spray position limited.
- Click here for a image
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1.2 Pressure Fed (External Atomization)
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Uses external pressure source, tank or pump, to force
material from nozzle. Material and air mix outside of
nozzle.
- Advantages: Delivers more material than 1.1.
Wider viscosity range. Sprays most materials. No air
nozzle wear. Spray in any position. Independent control
over air and fluid pressures.
- Limitations: Consumes most air. Creates most
fog.
- Click here for a image
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1.3 Pressure Fed (Internal Atomization)
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Material and air mix inside nozzle. This is how most
airbrushes function.
- Advantages: Less fog than 1.2. Larger patterns.
Less air consumption.
- Limitations: Coarse atomization. Fixed patterns.
Nozzles wear. Fast drying coatings not recommended.
- Click here for a image
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1.4 Pressure Fed (External Atomization) with Heated
Material
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Same as 1.2 except material is heated to reduce viscosity.
- Advantages: Better control. Reduced air and
fluid pressures. Limits overspray and rebound. Finer
atomization for a better finish. Better adhesion.
More film build per coat. Reduced blushing. Reduced
solvent use.
- Limitations: Not all materials can be heated.
Special paint formulations are required. Additional
equipment to maintain. Equipment must be explosion
proof (electrical). High electrical demand. Reduces
pot life for catalyzed coatings.
- Click here for a image
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1.5 Low Pressure Low Volume Atomization
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Material is atomized by LVLP jets of air optimumly
positioned to impinge onto the fluid stream of elliptical
cross section (instead of the conventional round cross
section) exiting the spray gun.
- Advantages: High transfer efficiency (65%
to 75%). Sprays well into recesses and cavities. Very
Portable system.
- Limitations: Atomization not as fine as that
of air spray. Not recommended for heavy materials
or where high production is required.
- Click here for a image
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1.6 High Volume Low Pressure Atomization
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Similar to that described in 1.2 except higher volume
and lower pressure (HVLP).
- Advantages: Same advantages as described
in 1.5 plus complies with most air quality regulations.
- Limitations: Same disadvantages as described
in 1.5 plus some systems for generating HVLP air may
be expensive.
- Click here for a image
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Airless (Hydraulic) Atomization
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Atomization caused by release of high fluid pressure
through small orifice. Most widely used by painting
contractors & maintenance painters.
- Advantages: High fluid capability. Large
patterns. Fastest spray application process. Low air
consumption. Limited fog and “bounce back”
– permits spraying into cavities.
- Limitations: Potentially hazardous hydraulic
injection. Higher rate of overspray. Sharp patterns;
difficult to blend. Expensive nozzles (tips). Coarse
atomization may flood surface. Equipment requires
top maintenance.
- Click here for a diagram
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2.1 Airless Atomization (Heated)
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Airless utilizing heat to reduce viscosity. Used by
furniture manufacturers and industrial finishers.
- Advantages: Better flow of material. Higher
solids per pass of gun. Viscosity control. Finer atomization
than 2.
- Limitations: Strict maintenance. Same limitations
as 2.
- Click here for a image
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2.2 Air-Assisted Airless
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Lower fluid pressures than airless (normally below
1000 PSI). Low pressure air is added via the air nozzle
to further atomize the already pre-atomized spray. Used
by furniture and industrial finishers.
- Advantages: Material savings 50% better than
air spray plus lower overspray and fog. Less tip wear;
longer pump life than airless. Higher film build per
pass than air spray.
- Limitations: Atomization not as fine as Air
Spray. Hydraulic injection may occur. Tip plugging.
Strict maintenance.
- Click here for a image
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2.3 Air-Assisted Airless (Heated)
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Uses same principle as 2.2 with the addition of heat
to reduce viscosity and improve flow.
- Advantages: Better flow of material. Higher
solids per pass of gun. Viscosity control. Finer atomization
than 2.2.
- Limitations: Same as 2.2 except with heat
to reduce viscosity. Hydraulic injection may occur.
Tip plugging. Strict maintenance.
- Click here for a image
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Electrostatic Atomization
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Voltage difference between paint dispenser (low speed
rotating disc or bell) and work causes paint to be attracted
to the grounded work. Used by most appliance manufacturers.
High production of uniformly shaped parts.
- Advantages: High transfer efficiency @ 65-95%.
“Wrap” around effect, coating other surfaces.
Minimum overspray.
- Limitations: Parts must be conductive. Limit
to shapes that may be coated. High production rate
required. High voltage and spinning cup or disc may
be hazardous.
- Click here for a diagram
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3.1 Electrostatics
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Material is atomized using conventional air, airless,
or air-assisted airless principles. Particles are electrically
charged and attracted to the work. Electricity may be
turned off to permit normal spraying.
- Advantages: “Wrap” around effect.
Material savings through minimized overspray. Use
with or without electrical charge.
- Limitations: Some conductive materials will
require special equipment. Parts must be conductive.
Difficult to penetrate cavities or recesses with power
supply on.
- Click here for a image
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3.2 Electrostatics (Heated Material)
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Same as 3.1 except materials are heated.
- Advantages: Ability to use the systems couple
together to get all the advantages as in 1.4, 2.1,
2.3 and 3.1.
- Limitations: Same limitations as in 1.4,
2.1 and 3.1.
- Click here for a image
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3.3 High Speed Rotational Atomizers
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High speed (10K-70K RPM) rotating disc or bell gives
exiting paint particles velocity and direction. Voltage
differential then takes over and allows electricity
charged paint particles to attract themselves to a grounded
part.
- Advantages: High transfer efficiency. “Wrap”
around effect, coating other surfaces. Works well
with high solids coatings. Minimum overspray.
- Limitations: Parts must be conductive. Limit
to shapes that may be coated. High production rate
required. High voltage and spinning cup or disc may
be hazardous.
- Click here for a image
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