Machinery & Energetics

Analysis of the influence of the geometry of the working zone on the distribution of the electric field in powder coating systems

Vitalii Naumenko, Leonid Сhervinsky
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Abstract

The aim of the study was to establish the features of the spatial formation of the electric field in electrostatic powder coating systems and its influence on the powder deposition indicators and coating uniformity. The methodology combined a bench-top comparative experiment, three-dimensional electrostatic modelling of the “corona electrode – charged torch – grounded product” system, non-destructive measurement of the dry film thickness, determination of the powder deposition efficiency and statistical analysis of electrostatic and technological indicators for four configurations of the working zone. It was established that the cylindrical configuration was characterised by the smallest spatial heterogeneity of the electric field: the coefficient of variation of the electric field strength was 0.178 versus 0.261 for the rectangular, 0.311 for the combined and 0.330 for the configuration with a variable interelectrode distance. For this configuration, the highest value of powder deposition efficiency was also recorded – 74.9%, the largest average coating thickness was 77.5 μm and the smallest value of the coefficient of variation of the coating thickness was 0.093. For the combined configuration and the configuration with a variable interelectrode distance, the powder deposition efficiency decreased to 63.1% and 60.7%, and the coefficient of variation of the coating thickness increased to 0.201 and 0.229, respectively, which reflected the transition of electrostatic heterogeneity into technological non-uniformity of the coating. Statistical analysis confirmed the significance of inter-configuration differences for the coefficient of variation of the electric field strength and the coefficient of variation of the coating thickness. Integral correlation analysis showed a close positive relationship between the coefficient of variation of the electric field strength and the coefficient of variation of the coating thickness (r = 0.84; p = 0.001), and local correlation analysis between the electric field strength and the coating thickness showed a statistically significant positive relationship (r = 0.79; p < 0.001). The practical significance of the results lies in the possibility of the use in the design, setup, and optimisation of working zones in electrostatic powder coating systems to improve the efficiency of powder deposition and coating uniformity

Keywords

electrostatic spraying; deposition efficiency; spatial heterogeneity; interelectrode distance; dry film thickness; coefficient of variation

Suggested citation
Naumenko, V., & Сhervinsky, L. (2026). Analysis of the influence of the geometry of the working zone on the distribution of the electric field in powder coating systems. Machinery & Energetics, 17(2), 50-64. https://doi.org/10.31548/machinery/2.2026.4
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