Jennifer

1

• Powder Coating

Presented By
Jennifer Erle
Amberlee French
Sarah Bennett
Josh Hamilton
John Schmitt
2

• What is Powder Coating?

• Powder coating is a dry finishing process, using
  fine particles of paint, which are
  electrostatically charged and sprayed onto a
  workpiece.
• Once the powder is applied, the part is cured,
  causing the powder to adhere to the surface.

3
Painting Process

• Fine particles are fluidized in a feed hopper
• Powder is vacuumed into the spray gun
• A second burst of air increases the particle
  velocity
• Particles are then charged by high velocity
  friction
• Spray gun applies powder to the grounded
  workpiece
• Coated part is then oven cured

4
Electrostatic Spray System

• Specifications
• Particle Size Range
• 10 µm to 30 µm
• Bulk Particle Density
• 1.5 x 103 kg/(m3)
• Fluid (Air) Density
• 1.177 kg/(m3)
• Fluid (Air) Viscosity
• 1.85 x 10-5 kg/(ms)

5
Fluidized Bed Parameters

• Dimensions
• 0.4m x 0.4m x 0.4m
• Bed dimensions based on
• 50 lbs of powder
• Pick-Up Tube Diameter
• D 0.02 m
• Fluidization of the particles
• prevents clogging

6
Fluidized Bed Calculations
7
Volume Flow Rate Calculations

• The volume flow rate at the tip of the gun was
  tabulated
• vpowder 250 m/s
• Aguntip 3.14210-4 m2
• Vguntip 0.079 m3/s
• The second burst of compressed air volume flow
  rate was calculated
• V2ndburst 0.063 m3/s

8
Tribostatic Gun Layout
9
Curing Process

• Oven temperature
• 300 F
• Time for complete cure
• 20 minutes
• Curing causes a chemical reaction that bonds the
  powder coating to the workpiece.

10

• Why Use Powder Coating?

• Higher Quality
• Extremely Durable
• Environmentally Friendly
• Cost Efficient

11

• Advantages

• No solvents are used
• Over-spray (up to 98) can be reused
• More resistant to chipping, cracking, and fading
• Corrosion and chemical resistant
• Coating does not run, drip, or sag
• Thick coatings are easily done
• Simple clean-up and maintenance

12

• Disadvantages

• Thin coatings are difficult to produce
• Storage and handling of the powder requires
  special climate controls
• Color matching is somewhat more difficult
• Cure temperatures may be too high
• Difficult to coat sharp corners

13
Conclusion

• Key concepts involved in powder coating
• Fluidized Bed
• Mass Balance
• Bernoulli Equation
• Stokes Law
• Specific calculated properties
• Terminal velocity in fluidized bed
• Velocity in pick-up tube
• Volume flow rate of second burst of air

14

• Powder Coating

Questions ?
Presented By
Jennifer Erle
Amberlee French
Sarah Bennett
Josh Hamilton
John Schmitt