Linkedin
  • Book Printing UV
  • Conveyorized UV
  • Corrugated
  • Narrow UV
  • Newspaper Printing UV
  • Permanent UV Cover Production
  • Portable UV
  • Sheet-Fed UV
  • Sheet-Fed IR
  • Variable Data IR Dryers
  • Variable IR Data Inter-Station Dryers
  • UV Theory of Operation
  • IR Theory of Operation
IR Theory of Operation

The Oxytech Drying System uses an Allen Bradley PLC with an Operator Interface Touch screen controlled combination of heated air knife streams, radiated heat from short wave (SW) or medium wave (MW) IR dryer panels, and air evacuation in order to produce quality results.

The Drying System consists of the following major components:

  • Drying System Cabinet
  • Air Knife, Motor and Blower
  • Air Evacuation Motor and Blower
  • Operator Interface Touch Screen
  • Drying Cassettes to include:
    • Heated Air Knife Shells and Air Evacuators
    • Short Wave IR Panels
    • Medium Wave IR Panels ( high intensity)

The following describes the typical operating procedure for drying:

  1. The aqueous coated sheet will pass under the first Short Wave IR Dryer (SWIR). The short wave energy heats the substrate to evaporate solvents from the ink (NOTE: All coatings are porous), which accelerates the drying process. Short wave energy does have a minimal drying effect on aqueous coating due to its chemical composition. The aqueous coated sheet then passes under the first Medium Wave Dryer (MWIR). The medium wave energy heats the surface of the substrate, further accelerating the evaporation of solvent from the ink. Medium wave energy has a positive effect on aqueous coating due to its "color-blind".

  2. After the sheet passes the first SWIR and MWIR Dryer, it is"scrubbed" by two dual heated air knives that are crucial in setting up aqueous coating. The coated sheet must be scrubbed of excess water, which is the main component of aqueous coating. The volume of air will determine the effectiveness of the scrubbing action, and heated air accepts moisture more readily than ambient or chilled air.

  3. Once the sheet is scrubbed of excess moisture, an evacuator hood is placed adjacent to the heated air knife section to remove the moisture-laden air from the press extension and / or delivery area.

  4. The processes in steps 1, 2 and 3 are repeated again for additional dwell time, up to two more times. Through extensive testing, we have found that the more dwell time allowed in the drying process, the more effective it will be.

  5. MWIR Dryers are used to compliment the effect of the SWIR Dryers. SWIR Dryers are not colorblind; light colors and metallics reflect heat, and dark colors absorb. The effect on opaque or transparent coatings is minimal, but the intensity of SWIR Dryers is required for high speeds, heavy stocks and / or board.

  6. MWIR Dryers are colorblind. They affect the ink, coating and varnish the same. However, they do not have much intensity, which is needed for high speed, heavy stock and / or board. The combination of SWIR and MWIR as with this drying system is a perfect balance to cover all situations.

  7. Some presses may be equipped with a delivery hood to remove excess heat and spray powder from the press extension. All delivery hoods should be equipped with a damper. Upon start-up, the damper should be adjusted to remove the "right amount" of excess heat and spray powder. An un-dampened delivery hood will create spray unit application problems.

  8. Drying Package evacuators and / or delivery hoods are not designed to remove excessive coating odor. If excessive coating odor is present with the drying package and delivery hood, consult your coating manufacturer. Chemical substitutions can be made to alter coating odor without sacrificing performance.

  9. If the Drying Package is supplied with a delivery pan cooling option, this option is used to prevent heat warp of the lower press pans or guiding mechanism. The pan cooling option is not used to remove heat from the printed or coated sheet.

  10. With the printing / coating process, it is crucial to maintain correct pile temperature. Too much or too little heat can cause spoilage. In our experience, optimal pile temperatures for process work and coating jobs are as follows:

    1. First Pass 96 - 98 F (35.5 C - 37 C)
    2. Second Pass 92 - 95 F (33 C - 35 C)

  11. Always consult your coating supplier for their recommendation. The pile temperature readings should be taken at the darkest color printed, and approximately 2" (51mm) down into the pile. This drying system includes a hand held optical pyrometer for accurate pile temperature sensing.

  12. All aqueous coatings are not created equal. Typically, work and turn coatings will have a faster dry rate than high gloss coatings. Your coating manufacturer can tailor individual coatings to your specific needs. Always choose an established, reputable coating manufacturer. These manufacturers have been in the coating business for a great deal of time, and the knowledge they have will be invaluable to the success of your operation.

For additional information regarding the IR Theory of Operation and how OXYTECH SYSTEMS and our family of quality products for the graphic arts and printing industries can address your needs, please contact us today.