Anilox
Encyclopedia
In printing
, anilox is a method used to provide a measured amount of ink to a flexo
printing plate.
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. Depending on the design of the printing press, the anilox roll is either semi-submerged in the ink
fountain, or comes into contact with a so-called metering roller, which is semi-submerged in the ink fountain. In either instance, a thick layer of typically viscous ink is deposited on the roll. A doctor blade
is used to scrape excess ink from the surface leaving just the measured amount of ink in the cells. The roll then rotates to contact with the flexographic printing plate which receives the ink from the cells for transfer to the printed material.
The characteristics of an anilox roll determine the amount of ink that will be transferred to the plate: angle of the cells, cell volume
, and line screen. A 60 percent angle ensures maximum density
in a given space. Lower volume makes for less ink. Low line numbers will allow for a heavy layer of ink to be printed, whereas high line numbers will permit finer detail in printing. Both cell volume and line screen are closely correlated.
Anilox rolls are often specified by their line screen, which is the number of cells per linear inch. These often range from around 250 to upwards of 2000, though the precise numbers vary by manufacturer. Most rolls sold are within 800 LPI, although a spike in demand for those with 800-1200 lines has been seen. Anilox rolls are almost always designed to be removed from the press for cleaning and for swapping out
with different line screen rolls. Depending on the detail
of the images to be printed, the press operator will select an anilox roll with a higher or lower line screen. Low line screen rolls are used where a heavy layer of ink is desired, such as in heavy block lettering. Higher line screens produce finer details and are used in four-color process
work such as reproducing photographs. Often a job will require a different line screen for each color to be printed. Experienced press operators are skilled at determining the appropriate anilox rolls for a given print job.
Though large wide-web flexo rolls are only maneuverable by overhead crane
, on smaller presses anilox rolls are often handled directly by operators. Extreme caution must be taken when handling these pieces of hardware as a single bump against a hard surface or sharp corner can destroy the delicate cell structure on the surface and render a roller completely useless, at a cost of around 5000 for even small narrow-web rollers. Nicks and scratches add up quickly, so fine brushes (never brass brushes) are used for cleaning the anilox roll. Similarly, anilox rollers that are used with water and oil based inks, which dry when left sitting out and unagitated, must be cleaned immediately after use or a problem known as plugging occurs, where minuscule amounts of ink dry in the cells. This leaves tiny, but unacceptable, pinhole
s in anything printed from the roll in the future.
Anilox rolls were originally made using a diamond
pecking machine, but modern rolls are laser engraved
.
Printing
Printing is a process for reproducing text and image, typically with ink on paper using a printing press. It is often carried out as a large-scale industrial process, and is an essential part of publishing and transaction printing....
, anilox is a method used to provide a measured amount of ink to a flexo
Flexography
Flexography is a form of printing process which utilizes a flexible relief plate. It is basically an updated version of letterpress that can be used for printing on almost any type of substrate including plastic, metallic films, cellophane, and paper...
printing plate.
An anilox roll is a hard cylinder
Cylinder
Cylinder most commonly refers to:* Cylinder , a three-dimensional geometric shapeCylinder may also refer to:-Science and technology:* Cylinder , the space in which a piston travels in an engine...
, 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. Depending on the design of the printing press, the anilox roll is either semi-submerged in the ink
Ink
Ink is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush, or quill...
fountain, or comes into contact with a so-called metering roller, which is semi-submerged in the ink fountain. In either instance, a thick layer of typically viscous ink is deposited on the roll. A doctor blade
Rotogravure
Rotogravure is a type of intaglio printing process; that is, it involves engraving the image onto an image carrier...
is used to scrape excess ink from the surface leaving just the measured amount of ink in the cells. The roll then rotates to contact with the flexographic printing plate which receives the ink from the cells for transfer to the printed material.
The characteristics of an anilox roll determine the amount of ink that will be transferred to the plate: angle of the cells, cell volume
Volume
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....
, and line screen. A 60 percent angle ensures maximum density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
in a given space. Lower volume makes for less ink. Low line numbers will allow for a heavy layer of ink to be printed, whereas high line numbers will permit finer detail in printing. Both cell volume and line screen are closely correlated.
Anilox rolls are often specified by their line screen, which is the number of cells per linear inch. These often range from around 250 to upwards of 2000, though the precise numbers vary by manufacturer. Most rolls sold are within 800 LPI, although a spike in demand for those with 800-1200 lines has been seen. Anilox rolls are almost always designed to be removed from the press for cleaning and for swapping out
Interchangeable parts
Interchangeable parts are parts that are, for practical purposes, identical. They are made to specifications that ensure that they are so nearly identical that they will fit into any device of the same type. One such part can freely replace another, without any custom fitting...
with different line screen rolls. Depending on the detail
Image resolution
Image resolution is an umbrella term that describes the detail an image holds. The term applies to raster digital images, film images, and other types of images. Higher resolution means more image detail....
of the images to be printed, the press operator will select an anilox roll with a higher or lower line screen. Low line screen rolls are used where a heavy layer of ink is desired, such as in heavy block lettering. Higher line screens produce finer details and are used in four-color process
CMYK color model
The CMYK color model is a subtractive color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and key...
work such as reproducing photographs. Often a job will require a different line screen for each color to be printed. Experienced press operators are skilled at determining the appropriate anilox rolls for a given print job.
Though large wide-web flexo rolls are only maneuverable by overhead crane
Crane (machine)
A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of...
, on smaller presses anilox rolls are often handled directly by operators. Extreme caution must be taken when handling these pieces of hardware as a single bump against a hard surface or sharp corner can destroy the delicate cell structure on the surface and render a roller completely useless, at a cost of around 5000 for even small narrow-web rollers. Nicks and scratches add up quickly, so fine brushes (never brass brushes) are used for cleaning the anilox roll. Similarly, anilox rollers that are used with water and oil based inks, which dry when left sitting out and unagitated, must be cleaned immediately after use or a problem known as plugging occurs, where minuscule amounts of ink dry in the cells. This leaves tiny, but unacceptable, pinhole
Pinhole
Pinhole may refer to:* Pinhole , a rock band from Liverpool, England, later to become The Dead 60s* Pinhole , a song by Japanese rock band Ogre You Asshole* Pinhole camera, a camera that uses a pinhole to form an image instead of a lens...
s in anything printed from the roll in the future.
Anilox rolls were originally made using a diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
pecking machine, but modern rolls are laser engraved
Laser engraving
Laser engraving, or laser marking, is the practice of using lasers to engrave or mark an object. The technique does not involve the use of inks, nor does it involve tool bits which contact the engraving surface and wear out...
.