Graphic Design & Printing Technology

Graphic Design & Printing Technology

Adjusting the air blast:- The purpose of air blast is to float the top most sheet
above the rest ofthe pile on a blanket of air. The amount of airblast needed
will warry depending on the weight and size of the paper sheet.

Adjusting the registration system

Positioning the pull in rollers and double sheet detector:- Before allowing the
feeder mechanism to sent a sheet to the registration units, the pull in wheels
(running wheels) and the double sheet detector must be set. Adjust the pull-in-
wheels to a uniform pressure so that each sheet is pulled squarely from the
feeder on to the registration board. Double sheet detectors cause the press to
stop when a double is detected. Set the device to pass the thickness of one
sheet and trip the press if more that one sheet is fed.

Setting the register board and sheet control:- Next allow the press to feed a
sheet into the registration unit and to stop if in contact with the head stop.
Line up the conveyor belts, straps or skid rollers to the sheet size. Adjust the
pull guide to push or pull the sheet. Inch the sheet into the grippers that pull it
beween the impression cylinder and the blanket cylinder and allow it to transfer
to the delivery system.

Positioning the image on the paper:- The image must be positioned squarely
on the paper by adjusting the control knob of the stop bar. This stop bar can be
tilted in either direction. Moving the stop bar eliminates the need of adjusting
the plate on the plate cylinder.

Setting the gripper bite control:- Small vertical movement of image can be
made by moving the paper stop bar foward or backward allowing a larger or
smaller gripper bite. Large vertical movements of the image on the paper are
made by moving the plate cylinder.

Adjusting the delivery unit:- Move the sheets to delivery units and adjust the
delivery side table guides before the sheet is released from the chain grippers.
Allow the sheets to drop on to the delivery table and position the table and
joggers.

Checking the entire system:- In order to check the entire system start the
machine and allow paper to pass from feeder to delivery. The sheet should be
smoothly and consistantly fed on the registration board. Each sheet should be
uniformly registered and transferred to the printing unit. The delivery system
should remove each sheet and stack a perfect pile on the outfeed table.