Anilox Roller: What does it do? What are the basic specifications?
Anilox is a method used to provide a measured amount of Coating. The coating process depends upon the precise controlled transfer of coating. An anilox roll is a hard cylinder, usually constructed of a steel or aluminum core which is coated by an industrial ceramic whose surface contains millions of very fine dimples, known as cells. The excess coating is metered or “doctored” from the surface of the roll leaving coating only in the cells of the anilox roll. The choice of the correct anilox roller is of central importance for an optimal coating result. Anilox rolls are designed to be removed from the press for cleaning and for change with different line screen rolls.
In coating, an anilox roll is used to provide measured amounts of coating to a coating blanket and can be thought of as a precise metering roll.
Anilox rollers contain following details
Type -Angle, Line count, Transfer Volume, Wall/ cell ratio.
1) Type -Angle
The most used cell types are Hexagonal cell and Helical Cell.
- Hexagonal is typically for Water-Based Coating Applications
- Helical is typically for UV-Related Coating Applications
Angle: Angle indicates how the cells were engraved and their line up across the anilox.
2) Line count
Line count is the number of cells per linear inch/cm
Europe has the standard as L/CM or lines per centimeter.
America has the standard as LPI or lines per inch.
1 inch = 2.54CM, which helps for calculation as 1 LPI = 2.54 L/CM.
Example: 150 LPI = 60 L/CM (150/2,5)
According to coating requirement on the job (images and substrate), press operator will decide for a high/low cell volume anilox
Low line screen is used for heavy layer of coating, and anilox has larger cells for higher volume of coating
High line screen is used for thinner layer of coating, and anilox has smaller cells for lower volume of coating.
3) Transfer Volume
Europe`s standard is cm³/m² or cubic centimeter per square meter, which means 1 cm³ of ink will be transferred onto 1 m² of paper.
America`s standard is is a Billion Cubic Microns per square inch, usually mentions as BCM
Cleaning of the Anilox Roller
After each printing cycle, the rollers need to be cleaned immediately. Delayed or interrupted cleaning should avoid otherwise the transfer of defined ink or coating can not longer be guaranteed. Nevertheless, for smooth running, daily cleaning is unavoidable. The degree of contamination depends of toller type and cleaning process.
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