Powder Coating: How to get a Maximum Overspray Recovery?
Daniel Smalzi, TAMA AERNOVA Sales Manager
Powder coating is an optimal solution for surface treatment, which is why it’s used in the most varied industrial fields and more.
The powder coating process consists of two stages:
- the first one in which the processed parts are covered with synthetic resin-based paint powder, for example epoxy powders, which adhere by electrostatic effect;
- the second one in which the parts pass through an oven where, thanks to the high temperature, the paint melts and polymerises creating a uniform and adherent layer.
A typical plant is composed of:
- an overhead chain conveyor belt where the parts (generally sheets, pipes, profiles and manufactured products) are hung;
- a washing system;
- a polymerization oven;
- one or more spray booths with electrostatic guns.
The spray booth is the area where the powders are sprayed, and it’s here that the Tama Aernova filtration systems come into play: the V-AREN Cyclone, the MJT Vertical Cartridge Filter and the New ORV Horizontal Cartridge Filter.
The booth allows the passage of the components in the catenary and, to allow the process of manual retouching of the operator, it cannot be closed on all sides. It therefore becomes essential to have a correct suction system into the booth in order to prevent dust from coming out of the openings, guaranteeing the protection of the operator's health and the safety within the work environment. The application of dust by electrostatic effect creates a potentially explosive atmosphere inside the cabin. This atmosphere is a particular mixture of air-dust which, in the presence of an ignition source (for example a spark) and particular conditions environmental, can ignite and give rise to an explosion. For this reason, it is extremely important to install an efficient suction system that guarantees compliance with the limit represented by the MIE (minimum ignition energy) -> for further information on the subject, visit our ATEX page.
A final important fact to consider is the economic one. A proper suction system in the booth allows us to prevent the overspray dispersion, i.e. all the paint that does not adhere to the component in the automatic spraying process. In order to recover this powder and be able to reuse it by returning it to the painting system, a V-Aren Cyclone must be installed between the cabin and the cartridge filter. After several fluid dynamics studies, TAMA AERNOVA has managed to develop a cyclone that allows to obtain excellent results in terms of performance, confirmed by the measurements of our R&D department and by the direct experience of a significant sample of our customers who has detected an overspray recovery of more than 96%.
Two fundamental aspects to consider during the planning and the realization of our products are the correct sizing and the care in the construction. The powder removed by the cartridge filter in the booth must in fact always be recoverable, even in the moment immediately following the colour change. To ensure this, it is essential to carry out a very thorough cleaning not only of the application equipment, but also of the entire air circuit and powder circulation. The care taken in the construction of the V-Aren Cyclone avoids the generation of accumulations of powder inside it, accumulations that would contaminate the new colour after the change, slowing down the process by significantly reducing the percentage of reusable dust.
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