Electrode is Ceramic tubes ( Square /Round ) to which to which High Voltage is applied. Generally efficiency of Bare Roller Corona Treater is less compared to Silicone Sleeved Conventional Corona Treater and hence more power is required in the Bare Roller Corona Treaters. For this, multiples ceramic electrodes are employed depending upon line speed requirement.
Bare Roller Treaters are used in converting lines (printing, coating and laminating in particular) because more and more converting applications are employing water-based inks, coatings and adhesives. Where once the film extruder could provide treated film that was adequate for solvent-based converting, now the higher surface energy requirements of water-based (and later radiation-cured) converting necessitated in-line treatment on top of the treatment provided by the film extruder.
Bare Roller Corona Treaters are ideal for converting applications because it has following mentioned advantages :
1. The ability to treat both non-conductive and conductive webs.
2. No roll covering to fail which was a source of frequent problems with
3. Edge-to-edge treatment which the Covered-Roll could not do at that time.
4. Consistent treatment across the web, which is important as long as stripe
treatment, was not required.
5. A higher level of operator safety from electrical shock while providing easier
threading because of the open design.
6. Ozone removal and electrode cooling that maintained the electrode at a
stable temperature which eliminated warping and provided more consistent treatment while it provided an ozone safe work area.
7. A smaller diameter treater roll for a smaller more compact station.
8. A greater range of station mounting options to fit the line easier than most
Covered-Roll stations could provide.
However, the Bare Roller Corona Treaters are not without its limitations. They are:
- The Bare-Roll station required slightly more power (kW) to treat difficult to treat substrates to a given dyne level.
- The Bare-Roll station did not easily allow stripe or lane treatment which is frequently required on blown lines producing film for bags. This is especially true when the stripe treatment must be adjusted frequently to vary the treat and no-treat dimensions. Converting lines (printing or coating) seldom require stripe or lane treatment except for in-line printing on an extrusion line.