Busbars: define insulation coverage and connection zones separately
A busbar drawing should distinguish the surfaces requiring an insulating coating from bolted connections, contact faces and other areas that must remain coating-free. A general decorative powder-coating thickness range is not an electrical-insulation specification. The selected coating system, geometry and assembly requirements must be reviewed together.
Thickness inspection records show film build at the measured locations; they do not by themselves establish electrical suitability. Define any required electrical tests and acceptance criteria separately with the responsible engineering team before production.
- Mark insulation boundaries, masked connection faces, holes and transitions on the drawing.
- Specify the accepted coating product and thickness range for the application.
- Agree measurement locations around bends, edges and recessed features.
- Define inspection frequency, traceability and the disposition of out-of-range readings.
- Confirm any electrical test method, test conditions and reporting requirements before quoting.
Choose a measurement method for the actual substrate
Use a measurement method suited to the base metal, coating and part geometry. Cured-film readings and uncured-powder measurements are different measurements; a pre-cure check should not be reported as the final cured-film result. Confirm instrument verification and the measurement procedure in the inspection plan.
For an introduction to measurement technologies, see DeFelsko's Powder Coating Thickness Measurement & Paperless QA guidance: https://www.defelsko.com/resources/powder-coating-thickness-measurement-paperless-qa
Film build is a controlled process variable
Too little coating can reduce coverage and performance; excessive film can create appearance, cure, fit or edge-detail problems depending on the powder system. The correct range comes from the coating manufacturer, project specification and component geometry.
Geometry affects measurement
Edges, recesses, Faraday-cage areas, welds and complex shapes can build differently from broad flat surfaces. Measurement locations should reflect the functional and visible areas of the actual component.
Specify the measurement plan
- Target and allowable thickness range
- Measurement method
- Number and location of readings
- Treatment of edges, welds and masked transitions
- Acceptance rule for individual readings and averages