Graphic Design & Printing Technology

Graphic Design & Printing Technology

Front lay:-It is a metal tab or plate attached to the front end of the feedboard
on a sheet-fed printing press that stops the sheet of paper and holds it on the
feedboard while the side lay moves the sheet into position.

Side lay:- It is a device attached to the feedboard that aids in the lateral
positioning of a sheet of paper before a sheet is transferred into the printing
unit. Side lays are of two types- push type & pull type. Pull type side lays are
more accurate than push types.

Conveyor belts:-Endless belts which carry the paper to the front lay (headstop).

Running in wheels :- The sheets picked up by the suckers are forwarded to the
registration unit by the running in wheels.

Press register methods

The registration table carries each sheet using the conveyor belts to the front
stop where paper is aligned square with the printing system with the help of
side lay, ready to be captured by the grippers of the impression cylinders.

There are three press register methods- the three point guide system, the swing
feed system and the feed-roll system.

Three point guide system :- In the three point guide system the sheet is forwarded
to the front guides which may be two or four in number. While the sheet is
held against the front guides a side guiding mechanism pushes or pulls the
sheet into proper side alignment until the impression cylinder grippers take
hold of it. At this time the front guides are lifted out of the sheets path of travel.
As soon as the entire sheet clears the feedboard the guides drop back into
position to align the next sheet.

Swing feed system :- In this system the sheet is moved forward down the
feedboard and got to rest against front guides. The side guides then aligns the
sheet. After being properly guided the sheet is picked up by a set of grippers
usually mounted over the feedboard. The front guide moves out of the way
and the arm swings forward carrying the sheets into the gripper on the
impression cylinder.

Feed-roll system:-In this system the sheet is moved down the feedboard,
positioned against stops and side guides. While the sheet is at rest, it is firmly
gripped in its position by being pinched between upper and lower feed rolls or
cams. At a precise movement the front guides move out of the way, and the
feed rolls start rotating to drive the sheet forward and into the grippers on the
impression cylinder.