Poor adhesion during powder coating: Cause poor grounding and solutions
Proper grounding of the workpiece is a basic requirement for successful powder coating. If the grounding is inadequate, the powder particles will not adhere properly to the component – with serious consequences for the coating result and durability.
Why is good grounding so important?
During electrostatic powder coating, powder particles are electrically charged. These particles are attracted to the grounded workpiece by the electric field. Only with a good grounding connection can the charge be neutralised and uniform powder adhesion be achieved.
Typical causes of poor grounding
- Poorly conductive workpiece surfaces: Paint residues, oil films or oxide layers impair conductivity.
- Unsuitable suspensions: Worn, poorly conductive suspensions (e.g. painted hooks) interrupt the grounding connection.
- Contaminated contact points: Powder adhesion or contamination on holding systems impair the electrical connection.
- Lack of regular inspection: If the grounding is not checked routinely, defects can quickly creep in.
Recommended solutions
- Clean contact points: Clean retaining systems regularly and ensure that surfaces are bare and conductive.
- Use suitable hooks and hangers: Use metal hangers with good electrical conductivity.
- Routine measurement of the grounding resistance: The resistance should be less than 1 MΩ (ideally 0.1 MΩ).
- Avoid insulating layers: Workpieces must be free of grease, oil and corrosion protection layers.
Conclusion
Perfect grounding is the key to optimum adhesion during powder coating. With clean contact points, suitable suspension systems and regular checks, you can ensure an even, high-adhesion coating and significantly reduce rejects.
