electrostatic paint spray system is a highly efficient technology for
the application of paint to specific workpieces. Negatively charged
atomized paint particles and a grounded workpiece create an electrostatic
field that draws the paint particle to the workpiece, minimizing overspray.
this technology, an ionizing electrode, typically located at the paint
gun atomizer tip, causes paint particles to pick up additional electrons
and become negatively charged. As the coating is deposited on the workpiece,
the charge dissipates through the ground and returns to the power supply,
completing the circuit. The electrostatic field influences the path
of the paint particles. Because the charged particles are attracted
to the grounded workpiece, overspray is significantly reduced. Paint
particles that pass a workpiece can be attracted to and deposited on
the back of the piece. This phenomenon is known as "wrap."
transfer efficiency is the percent of sprayed paint that is applied
to the workpiece. The typical transfer efficiency for an electrostatic
paint spray system is 75%.
conventional paint spray systems, paint atomization occurs via high
velocity air jets forcing paint through small air holes in the paint
gun face caps. Air pressures used in these systems range from 40 to
80 pounds per square inch (psi), with air volumes of 8 to 30 standard
cubic feet per minute (scfm). The atomized paint particles travel at
high velocities and have a greater tendency to bounce off the object
being painted, as compared to electrostatic systems.
Cost will vary, depending upon specific applications: painting/coating
type, paint volume, workpiece specifications, and technique.
of paint applied to surface per year: 5,000 gals.
Paint procurement cost: $50/gal.
Transfer efficiency of electrostatic spray: 75%.
Transfer efficiency of high velocity spray: 50%.
Gallons of paint purchased: 6,667 gals for electrostatic, 10,000 gals
for high velocity.
Operating hours: 145 hrs for electrostatic, 200 for high velocity.
Labor rate: $45/hr.
Waste paint collected using dry filter system.
Dry filter replacement rate: 1.25 dry filters/hr.
Dry filter disposal cost: $1/filter.
Annual Operating Cost Comparison for Electrostatic Paint Spraying and
High Velocity Paint Spraying:
Economic Analysis Summary:
Savings for Electrostatic Paint Spraying: $169,100
First, we setup the test spraying apparatus.
Next, we take a black plastic sphere and place it a set distance from
the spray nozzle.
Now, we spray the sphere with elctrostatics turned OFF: 1-2-3-4 seconds.
(The setup is the same; the black backround was added to make the spray
Notice the coverage on the target.
Finally, we turn electrostatics ON, and spray a new sphere for half
the time: 1-2 seconds. (All other settings are kept constant, so half
the amount of material is sprayed.)
Notice the coverage on the target. The charged droplets wrapped around,
reaching the back of the sphere.