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Overcoming the Faraday Cage Effect in Powder Coating Application

August 22, 2019

Tied to the powder coating process, The Faraday cage effect takes place inside confined workpiece areas. The electrostatic fields flow, as the laws of physics command, but a seemingly invisible barrier degrades those forces as they move into a part's corner or recess. And, since the powder follows the path of those lines of charged energy, the tiny capsules can't help but treat these recesses as no-go areas. That's a problem.

Faraday Effect Consequences

Known by industry experts as a common process issue, there's no shortage of available solutions. Basically, the electrostatic charge isn't penetrating deep enough. Consequently, the powder coating materials cannot adhere to a sharp angle or deep recess. Instead, the field takes a shortcut to the nearest grounded surface. Or, as an electrical engineer would put it, the charge is taking the path of least resistance. Viewed up close, as the internal planes of a sharp workpiece corner all come together, the gap between them quickly decreases, so it doesn't take much for the invisible lines of force to "skip" the deepest areas of these workpiece features.

Weighing Brute Force Solutions

Although not elegant, the following troubleshooting proposals work. A blast of air pressure helps the powder coating push deeper and into the recesses. If that move doesn't yield good results, the addition of a slotted nozzle might just focus the flow. Other options include a higher flow rate setting and a change in gun distance. By moving a handheld powder coating pistol closer to the Faraday shielded area, the particles might just find their way deep enough into the no-go area. But there's no way these half-baked techniques can be endorsed by a professional service. Sure, there's a better chance of improved coverage, but that improvement comes at the cost of control. Without control, thicker coatings and uglier finishes are likely to spoil the overall look and weatherproofing performance of an otherwise meticulously treated workpiece.

These next Faraday Effect overcoming proposals separate the amateurs from the true professionals. Instead of using brute force, experts use finesse and adeptly configured equipment settings. The nozzle angle is subtly shifted so that the powder flow closely parallels the sharp angles of a component's corners. Recesses are treated in a similar fashion, or maybe the kV output of the electrostatic power supply is adjusted until the cage is all but eliminated. A flow rate adjustment brings the powder spray under control while a gun voltage of around 40 to 60-kV maximizes the surface charge. In other words, the Faraday cage effect is overpowered by knowing the ins-and-outs of this detail-oriented craft.

GP Industries Pty Ltd

Head Office

1 Regal Court,
Vermont South VIC 3133

Phone: (03) 9802 1355

Fax: (03) 9802 6027

Email: gp_ind@bigpond.com


Factory G,
20 Burgess Road,
Bayswater North VIC 3153

Phone: (03) 9761 7676

Fax: (03) 9761 7671

Email: gpfactory@bigpond.com

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