Electrosol Painting

1. Introduction

Electropainting is a method that uses high-voltage electric discharge to convert a paint spray to what is called electro(aero)sol. Its particles then allow controlled deposition on a surface resulting in a very little loss of paint.

The process conventionally uses high-voltage devices which are bulky, unsafe and expensive.

The project is aimed at development and elaboration of a compact, safe and low-cost unit for high-quality electrosol painting.

2. Project Description
2.1. Equipment

The unit includes a rotational sprayer and a high voltage supply. The voltage converter of the HVS is so compact that it permits placing it near the sprayer head. This results in improved safety and reduced cost, for no high voltage cables are needed.

2.1.2. High-Speed Sprayer VR-30

The sprayer is basically a high-speed air turbine with a sprayer head attached to its shaft. For more reliable service, the shaft is supported on two-row bearings. The solvent and the paint are fed to the head via a system of passages. An additional air passage is provided that enables control over the jet shape.

Specifications of VR-30 Sprayer

Paint work material flow rate 50-900 cm3/min
Head rotational speed Max. 30,000 rpm
Life to failure at max. speed service Min. 2000 h
Air pressure 0.2-0.3 MPa
Overall dimensions 135 by 100 by 100 mm
Weight Max. 1.8 kg

2.1.2. Low-Speed Sprayer

For less demanding applications, a simpler sprayer NR-4 may be used. It operates at 4000 rpm.

2.1.3. High Voltage Supply

The device consists of a control block and a voltage converter connected to it with a common cord. The control block supplies low voltage of desired value and form which is then converted to a preset high voltage. The converter is placed near the sprayer.

The system offers following advantages:

A. Safety.
(1) No high-voltage cables are used, for the high voltage is generated in the immediate neighborhood of the sprayer.
(2) For improved fire safety, a duplex spark suppression system is provided. It uses current stabilization and also switches HVS off as the electrode approaches an earthed component.
B. Optimum operation due to current stabilization which maintains the specific charge quantity at a preset level.
C. Compactness, light weight and reliable design of the converter.

Specifications of Korona-120-2 Continuous-Mode High Voltage Supply

Output voltage Max. 120 kV
Voltage amplitude Max. 12 V
Discharge current Max. 150 (A
Converter dimensions 60 by 60 by 315 mm
Converter weight 1.2 kg
Control block dimensions 320 by 285 by 140 mm
Control block weight 4 kg
Cord length Max. 20 m
Control block input voltage AC 220V ( 10%, 50Hz
Input power Max. 15 VA
Average life to failure 2500 h

2.2. Performance

The paint loss may be reduced to 2 % under industrial conveyor conditions. This holds especially well for mass-produced components featuring a low solid area, like grids, frames etc. The entire surface can be painted with a sprayer located on one side.

The high-speed sprayer ensures very good finish due to fine size of paint droplets.

The electric charging device can be used for any type of sprayer.

3. Novelty

Some engineering solutions used in the development are patentable.

4. Marketing

In its current condition, an electropainting system including the Korona-120-2 high voltage device and a sprayer of either VR-30 or NR-4 type is offered for sale.

The system components allow further improvement that can be carried out within project framework.

5. Applications

Mechanical and repair shops. Machine building factories.

DSc., Prof. William Zadorsky,
Academician of the Ukrainian Ecological Academy, 
Ukrainian State University of Chemical Engineering.
Pridneprovie Cleaner Production Center
Tel: +(380) 567 440210
Tel/fax: +(380) 562 470813

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