Silap

Powder coating plant with UV dryer

elios_logo_nero

 

elios_logo2_EN_nero

impianto003

Introduction

One of the most commonly used coating techniques, particularly in industry, is the powder coating: the workpieces are painted with a powder coating based on synthetic resins, which adheres due to electrostatic effect, and then placed into an oven (with inside temperature between 180 and 250 °C) where the coating, due to the temperature, first melts and then polymerises, thus resulting in an adherent layer.

The current situation

With a powder coating, it is still possible to achieve a great performance in terms of both finishing and of mechanical seal. One of the problems that the operators of this sector face is the relatively high operating temperature of the furnace; in cases in which delicate components were to be treated, it was impossible to paint them, forcing the operators to implement other techniques.

The innovation

Euroimpianti Srl (www.euroimpianti.com), availing itself of a team of researchers, has developed a new polymer powder coating technique. It combines most of the advantages of the traditional powders with the advantages of the liquid polymer coatings. The result is a painting process that allows to use powder coatings with the supply of IR and UV rays.

The process

The UV system (patent no. VR2011A38) allows to carry out the polymer powder coating also on three-dimensional objects. In the first stages, the coating cycle coincides with a traditional cycle of powder pre-treatment and coating. The part to be painted, once washed and prepared, is placed on a conveyor belt and the powder coating is applied electrostatically, so as to provide sufficient coverage in a single step. At this point, the product leaves the spray chamber and enters the UV-IR oven. The casting and crosslinking process occurs in two different steps:

  1. At first, the IR treatment of the product begins: the temperature of the infrared rays must bring the surface to a sufficient temperature so the powder can melt and be distributed evenly;
  2. The second step, provides the treatment of polymerisation under ultraviolet rays, that lets to obtain a surface with the necessary sealing properties;

At this point, the product is finished, but it takes a few minutes before it can be handled: during the cooling stage, the polymerisation continues and the coating is fixed to the substrate.

The advantages

The use of UV technology allows a company to coat its products with significant and undisputed industrial advantages:

  1. The reduction of the coating time significantly cuts the hourly production cost and the energy consumption;
  2. The rapid drying and cooling, possible thanks to the low temperatures required for the melting and curing, also make the storage and packaging of the finished product faster, favouring the immediate clearing of the downstream storage space;
  3. The possibility to paint the product once already assembled also ensures a higher quality of finish and eliminates the risk to nick the previously treated surface during the production stage;
  4. Compared to the liquid coating, the use of powder coating provides an almost complete reduction of the environmental impact of the production process.

Research material

In order to verify the advantages offered by the UV paint, some comparative tests were performed between this technology and the traditional powder paint which gave very good results. The full report of the tests can be found by following the link below.