Graphic Design & Printing TechnologyAdvantages
- Flexography can be used for printing on a variety of absorbent and non
absorbent substrates. - Prints on the reverse side of transparent films.
- Rubber or photopolymer image carrier can be used for printing millions
of impressions. - Allows continuous pattern printing.
- Water soluable inks can be used and hence ecofriendly.
- Since it uses fast drying solvents the process is ideal for printing on
polyethene, the material used for plastic grocery bags and similar prod-
ucts. - Printing plate cylinders can be taken out of the press so that it can be
mounted and proofed as a pre-press operation.
Basic units
A flexographic press consists of three major units- the infeed, printing and
outfeed unit. Majority of flexographic printing is done on roll-fed materials.
Infeed unit and unwinding unit
Majority of flexographic printing is done on rollfed materials such as film,
foil, laminates used for food, medical and sanitary packages. The infeed system
consists of a roll stand with tensioning devices, dancer roller and brake to
control the web tension. Sheet-fed flexo is also possible for printing of thicker
materials such as corrugated board. Sheet-fed flexo infeed system are designed
to feed heavier stock.
Printing unit
In a flexographic printing unit, the ink fountain holds the ink. The fountain
rollers are made of soft or hard rubber and transfer the ink to the next roller in
the chain, the anilox roller. Anilox rollers are metal of ceramic roll engraved
with cells that carry ink to the plate cylinder.
There are two types of inking system- three roller system and two roller system.
A three roller inking system consists of an ink fountain roller, typically made
up of rubber, which passes
ink to the anilox roller.
The fountain roller moves
at a slower speed than the
anilox roller. This helps to
remove excess ink from
the anilox roller. This act
of removing excess ink is
called ‘doctoring’.