Coating Drying: Company GTL Knödel GmbH, Leonberg (GER)

The heat treatment of the lacquer coating for protective coatings of electronic modules is occurred by hot air or hot air in combination with infrared. During the hardening process of UV-lacquers a convective air flow is not necessary for the heat transfer, but as a circulation fluid for conveying of gasses arising by the cross-linking reaction. For lacquers, where laminating is caused by expelling the dilutor, a convective heat transfer by hot air is essential and a combination with STIR®-infrared heaters optional. It is essential as the drying process is a transportation-phenomenon and the air is the needed and favorable transportation-medium. For an additional infrared irradiation, STIR®-batwing radiators or rod-shaped emitters, with long- or medium wavelength of IBT are in use. It is fixed in the statutory provisions for dimensioning of drying equipment that “technical ventilation” for this drying process cannot be ruled out.

Combined convection and heater

GTL Knödel offers, with its approved heat treatment system Entuca, the combined heat transfer system Irkon. Thereby standard system modules with 2.000 mm processing length for various working width are available; besides systems for heat transfer by convective nozzle ventilation plus long-wave STIR®-batwing radiators and accordingly medium-wave STIR®-rod-shaped emitters. The ratio of irradiation for the complete heat transferring system is selectable.

Ceramic coated metal-heaters are used as batwing radiators for the temperature range of 100 to 250°C. The according wave lengths are between 7.6 and 5.5 µm. Rod-shaped emitters are in use for temperature ranges from 400 to 800°C. They lare lying in the medium-wave irradiation range between 4.2 an 2.6 µm.

The absorption characterisitcs of typical paint resin and diluters in comparison to specified wave lengths will be included to the heater selection.

For the equipment system Knödel Entuca Irkon are available approx. ten various conveyors for the working width between 200 and 480 mm.

Source: magazine “productronic 01-2 / 2011“ page 32

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