electrostatic spraying
DESCRIPTION
microfabricationTRANSCRIPT
Electrostatic Spray Coating(Micro Fabrication Techniques )
By 1- Ahmed Abubakr 2- Mostafa Amer
Outline!Basic Idea of Electrostatic Spray
CoatingCharging MethodsCoating MaterialsAdvantages Limitations
Basic Idea of Electrostatic Spray Coating
Charging Methods(1-Corona Discharge)
Charging Methods(2-Conduction Method)
Charging Methods(3-Induction Method)
Coating Materials
Key Properties
Resistivity Conductivity
Flammability
Coating Materials: materials (or paint or photoresist) used to coat the object or target.
Coating Materials(Resistivity & Conductivity)
Optimum range for resistivity to spray best is 20-200 megaohms.cm
Lower resistivity materials may require special fluid tube or hose configurations to prevent them from shorting out.
If the coating material is too resistive a higher conductive solvents are used to reduce the resistivity.
Coating Materials(Resistivity & Conductivity)
Coating Materials(Flammability)Coating materials have a flashpoint
temperature rating to indicate the temperature at which vapors from the material are flammable.
How easily these vapors can be ignited ?!Flammable materials may ignite if an
uncontrolled electrical discharge (spark) occurs.
Note: any metallic or otherwise electrically conductive object is in the vicinity should be properly electrically grounded
AdvantagesSaves material because it utilizes overspray and
reboundReduces clean-up and maintenance time.Increases production rates Reduces equipment wear because lower air and
fluid pressures are used.Eliminates secondary operations in some cases
because of wrap-around.Better atomization because like charges repel
each other causing the spray pattern to open upbetter using less air pressure
LimitationsUniformity of coverage will vary depending on
the size and contour of the object.The product to be sprayed must be a conductor.
Parts which are not conductors can be sprayedby having parts immersed in a special solutionto make them conductors.
Conveyors, as well as the product, must begrounded at all times.
Electrostatic spray guns are limited to the amount of fluid they can efficiently charge in agiven period of time.
References 1- Basic electrostatic spray finishing,
Retrieved from: http://www.elliottequipment.com/MediaLibraries/ElliottEquipment/PDFs/Ask%20Elliott/ELECTR_1.PDF
2- Electrostatic Spraying, Retrieved from: http://infohouse.p2ric.org/ref/50/49414.pdf
Questions!