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#184 Electrostatic Painting

Category : Painting
May 9, 2014

The electrostatic painting is a type of atomized coating where the paint particles are atomized with centrifugal, pneumatic, hydraulic forces, and static electricity charged to electrically coat the workpieces.

As well known, the static electricity is generated on the surface of glass rods when the rods are rubbed with silk cloths and furs alike. The silk rubbed glass rods would be charged positively (+), and the fur rubbed glass rods are charged negatively (-).

The positively charged objects are attracted to the negatively charged objects, but the positive and positive, or negative and negative charges will repel each other. As shown on [Fig.1], when the workpiece to be painted is grounded and the paint atomizing device is charged negatively at high voltage, the workpiece would be positively charged and they form an electrostatic field. The paint particles negatively charged exiting the atomizing device would then be attracted and coat the workpiece. Feature of this method is that it wastes almost no paint as compared to hand-held spray guns.

[Fig.1] Conceptual diagram of electrostatic painting system

Industrially used electrostatic painting devices are broadly classified on [Table 1]. There are paint spray devices that are fixed stationary types, conveyor applicable types that move over some distances, and hand-held types that can be used in various ways by operators similar to the conventional hand-held spray guns.

[Table 1] Classification of electrostatic painting devices
FunctionStationary typeAutomated typeHand-held type
DescriptionThe painting device is stationary fixed, and placed in front of the workpiecesThe painting device is equipped with a reciprocating system, and used in reciprocal manner.The painting device is hand-held and used at will by operators.
Atomizing devicePneumatically atomized, Electrically atomizedPneumatically atomized, Electrically atomized, Airless atomizationPneumatically atomized, Airless atomization
Discharge electrodeFixed, RotatingFixedFixed
Voltage80〜90kV70〜90kV30〜60kV
OperationSemi-automatic, automaticAutomaticManual
ApplicationSmall variety mass productionSmall variety mass productionLarge variety small production
Production formatConveyors usedConveyors usedGeneral hand-held

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