Nordson Corporation

David H Chow

Walter H Cobbs, Jr

Harry J Lader

Merle N Hirsh

Method and apparatus for charging powdered particles and delivering only these charged particles to a workpiece. A high voltage electric field is created between upper and lower surfaces. Powder is continuously delivered to the lower surface. The lower surface is vibrated to bounce the particles so that each repeatedly contacts the lower surface and picks up an electrostatic charge with each contact. When the charge from the particle is great enough to overcome gravity, the particle levitates and is thereafter transported to a workpiece, where it adheres by electrostatic attraction. Three important features of this method are: (1) No uncharged particles are levitated to the workpiece, thereby eliminating the need for recirculating uncharged powder. (2) The method is capable of producing high throughput of charged particles. (3) The method is capable of producing powder with a controlled charge level.

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Bridgewater, NJ, United States of America

David H Chow