Abstract: The present invention is directed to a process for the application of fluoropolymer to a preselected area of a threaded fastener, and particularly to substantially all of the threads of the fastener. The fluoropolymer is supplied to a spray nozzle in powder form and is subjected to a triboelectrostatic charging process so that individual particles discharged from the spray nozzle are electrically charged to between about 1×10−7 to about 3×10−3 coulombs per kilogram. In the preferred form of the invention, the fluoropolymer powder is triboelectrically charged, entrained in an air stream discharged from the nozzle and directed onto the preselected area of the fastener. In this manner a generally uniform powder coating is deposited onto the preselected area of the fastener while the fastener is maintained at room temperature.

Abstract: The present invention is directed to a vibratory powder feeding and metering apparatus that achieves the above-mentioned requirements. Generally, the apparatus of the present invention includes a housing defining a powder reservoir, a powder storage hopper having an outlet disposed to deliver powdered resin to the reservoir, a powder distribution block having one or more generally vertical fill tubes, a plurality of discharge ports extending from the reservoir to the fill tubes in the distribution block, and a vibration device to which the housing is mounted. Typically, the fill tubes are in communication with individual spray nozzles for transmission of the powdered resin. The housing also carries an adjustable barrier which serves as a dam to control or meter the flow of powdered resin into the discharge ports.

Abstract: The present invention is directed to a vibratory powder feeding and metering apparatus that achieves the above-mentioned requirements. Generally, the apparatus of the present invention includes a housing defining a powder reservoir, a powder storage hopper having an outlet disposed to deliver powdered resin to the reservoir, a powder distribution block having one or more generally vertical fill tubes, a plurality of discharge ports extending from the reservoir to the fill tubes in the distribution block, and a vibration device to which the housing is mounted. Typically, the fill tubes are in communication with individual spray nozzles for transmission of the powdered resin. The housing also carries an adjustable barrier which serves as a dam to control or meter the flow of powdered resin into the discharge ports.