PCOBG

PC 2018 BG website version

Issue link: https://www.e-digitaleditions.com/i/1063364

Contents of this Issue

Navigation

Page 7 of 125

4 POWDER COATING, December 2018 B Back ionization. A condition that can occur during electrostatic application of powder, in which an excessive buildup of charged powder particles limits further powder from being deposited on the sub- strate and can reverse the electrical charge of the surface layer of powder particles. Also called electrostatic rejec- tion or repelling. Bulk density. Mass per unit of volume in powder form, including the air trapped between particles. C Cloud chamber technique. A method of moving a charged or uncharged object through a charged or uncharged cloud of powder in an enclosed chamber. Compatibility. The capacity of powder coatings from different sources or of dif- ferent compositions to be combined and applied so as to yield no visible or mechanically measurable differences in the cured film or application properties. Coronacharging. The process of induc- ing a static electric charge on powder particles by passing the powder through an electrostatic field generated by a high-voltage device. Cure end point. The point either during or following the cure schedule at which the powder-coating film is determined to have developed specified properties. Cure schedule. The time/temperature relation required to properly cross link a thermosetting powder coating. Cut-through resistance. A powder coat- ing film's resistance to penetration from the combined application of sharp edges, heat, and pressure. A formalized test used by applicators of insulative powder to electrical motors. D Delivery. The process of moving the powder coating through the application equipment to the end product. Dry blending. A process of powder coat- ings' manufacture in which ma terials are blended without melting. E Edge coverage. A powder coating's capability to flow over, build, and ad here to sharp corners, angles, and edges. Electrostatic deposition. A technique of moving and charging powder so that it is deposited on a grounded substrate. Electrostatic fluidized bed tech - nique. A deposition method of charg- ing fluidized powder so that it is de - posited onto a grounded substrate. Electrostatic rejection. See Back ionization. Electrostatic spray technique. A depo- sition method of spraying and charging powder so that it is deposited onto a grounded substrate. See Corona - charging and Tribocharging. F Faraday cage effect. A condition that can exist on a substrate be cause of its geo- metric configuration, which can inhibit the electrostatic application of powder particles at that specific localized area. Film formation. The forming of a con- tinuous film by melting powder particles and coalescing them by the application of energy. For thermosetting materials, a chemical reaction, through the further ap plication of energy, also takes place. The fused and cured film has the unifor- mity, color, toughness, and other proper- ties associated with protective and deco- rative coatings. Flocking deposition technique. A deposition method of applying powder by spray to a substrate heated above the melt point of the powder material. Fluidized bed. A fixed container in which powder is suspended in a continu- ous stream of air. Preheated objects can be coated by dipping directly into a flu- idized bed. The fluidized bed can also be used to facilitate transfer of powder mate- rials to an alternate application site. Fusion. The melting and flow of individ- ual powder particles under the influence of heat to form a continuous film. G Gel time. Interval required at a given temperature for a powder to be trans- formed from a dry solid to a gel-like state. Glass plate flow. See Plate flow. Grounding. An electrical grounding of the item to be coated. I Impact fusion. The tendency of finely divided powders to combine with other particles in the application equipment during the application process. Glossary of Powder Coating Terms POWDER COATING GLOSSARY

Articles in this issue

view archives of PCOBG - PC 2018 BG website version