Reference Book
The device can be positioned to the blanket or impression cylinder. The cloth
width will be equal to the width of the printing unit. The cleaning liquid is
supplied in accordance with the degree of soiling and is sprayed on to surface
by a row of nozzles. The cloth will squeeze through the cylinder and clean it.
Ink cleaning unit is also equipped with a special spraying device. Located
opposite to the spraying device there is an ink trough which is used to squeeze
off the ink on the roller.
Automatic Plate changing: When mounting a set of plate for multicolor jobs,
it is essential that the printing plates should be clamped in accurate position on
the plate cylinder. This is
achieved by means of
punching register holes on
the printing plates and
suitable guide system. This
is done with the help of a
plate punching device in
the press room. In
automated plate changing
system the plate is placed
ready for mounting on the
plate cyliner. The plates of
the earlier job will be
ejected automatically which is followed by the automatic feeding clamping
process of the plate for the new job.
Major advantages of automated plate changing system are that- no manual clamping of the plate is required,
- no operator related error will occur and
- plates change over can take place on all printing unit at the same time.
Estimation procedure in offset printing
Estimation is a complex process of predicting the cost of a job based on client
submitted specification which includes the desired quantity, dimension, type
of paper, the number of ink colours, along with many other factors pretaining
to the job.
For example, estimation factors for the production of 500 business cards are
the time spend in pre-press for preparing the digital file and the plate, time
spend in the press for printing, for cutting the individual card and the time
spend for packing the finished card in addition to the material cost, labour and
energy cost.