Repulsion effect (Faraday effect) in powder coating: causes and solutions
During powder coating, it often happens that powder does not penetrate deep or narrow areas of a workpiece. This phenomenon is known as the Faraday effect. It results in critical areas such as inner edges, grooves or drill holes being poorly coated and optical defects occurring.
Causes of the Faraday effect
The Faraday effect is caused by electric field lines that are mainly concentrated on outer edges and raised surfaces. In deeper areas, the electric field weakens, so that less powder is attracted.
Recommended solutions
- Reduction of high voltage: By lowering the high voltage during the coating of areas that are difficult to access, the field strength is adjusted and the powder can penetrate better.
- Use of PCC technology: Precise current control in modern control units such as Gema OptiStar enables better coating behaviour in critical areas.
- Manual reworking: For extremely angular geometries, manual pre-coating with reduced powder flow is recommended.
- Optimised gun positioning: A precise gun angle and the correct distance from the workpiece improve powder penetration.
Conclusion
The Faraday effect poses a challenge in powder coating, but can be effectively minimised through adapted processes and modern technology. With the right strategy, you can achieve a uniform and high-quality coating even on complex components.
