Flexographic printing is defined as a method of direct rotary
printing that uses special rubber or photopolymer material. The printing plates
are affixed to plate cylinders of various repeat lengths, which are linked by a
cell structure (anolox roll) which is used to meter the flow of the ink on
roll. It carries a fast drying fluid ink to the plates that print on a variety
of substrates (paper / plastic / nylon / polypropylene / cellophane / LDPE /
LLDPE / etc.).
Flexographic printing is a rotating method for every
revolution of the printing plate cylinder an image is produced. If the image is
stepped several times around a cylinder several images may be produced in one
revolution.
Digital Flexo
Photopolymer Plate Making Equipment
Due to the nature of the printing process there are factors
that don't exist with other print methods such as offset and gravure. Because
flexographic employs a flat but flexible printing plate that is stretched
around a curved cylinder and the image on the plate distorts when the plate is
mounted on the printing cylinder. A circle shape for example distorts into an
egg shape. The amount of distortion depends on many factors including cylinder
size, plate size, and the amount of distortion depends on a number of factors,
including cylinder size, plate size, and the amount of adhesive mounting tape
used to attach the plate cylinder.
Another aspect of flexographic printing is the solids (line
art) print differently than screens (dot patterns). That is because the
printing plate is relatively soft and the ink on its surface must be pressed
against the substrate to print. Thus the amount of pressure applied to the
printing plate is critical For example more pressure is needed to print a dense
and heavy solid than to print a screen tint.
Flexo Photopolymer
Printing Plate
Whichever method used to set up the printing press, one
design implication must remain clear is that you may not be able to
successfully print one color screens and solids on the same printing plate or
printing station. This is very different from offset printing where the solids
and screens of a given color can be printed with a single printing plate.
I have been involved with a number of manufacturing purchases and plant start ups and development of new packaging materials from extrusion, printing, laminating, converting, etc. for over 10 years. Flexography India Press offering services for international market in Dubai, Egypt, Kenya, Oman, and Tanzania. - http://www.flexographyindiapress.com
