Reference Book
Feeding the test sheet:- A small quantity of make ready sheet must be placed
on top of the press sheet pile. Make ready sheets are sheets of same weight
and surface finish as the final sheets that are used for initial press setup. These
make ready sheets should be run through the press to detemine if any
adjustments are required. The following steps should be considered while
feeding the test sheets.- Moisten the plate with fountain solution using a cotton pad.
- Start the press.
- Lower the dampening form roller to the plate.
- Allow the press to run for some time while checking the plate for dampness.
- Lower the ink form rollers to the plate cylinder.
- Start the vacuum and blower motor.
- Set the press on impression and run a sheet of paper.
- Turn off the impression and raise the ink form rollers.
- Stop the machine.
- Check the image position and make necessary adjustments to achieve
position, ink water balance and desired ink coverage.
Checking the test sheets:- Inspect the test sheet carefully. The image on the
paper should be clear, well inked and free from background tone. Check for
scum which indicates an excessive amount of ink or insufficient amount of
dampening solution. The ideal ink-water balance occurs when each printed
sheet takes exactly the same amount of ink and water while being metered to
the plate.
Check the position of the image:- These check should include lateral (left to
right) and vertical (up and down) position.
Cylinder and roller pressure
There are several pressure checks that must be made to cylinders and rollers
on a daily basis. These checks should also be made whenever rollers, roller
coverings, blankets, plate thicknesses, and paper thicknesses are changed. The
sequence of pressure checks is given below:
1) Check dampener form roller-to-plate pressure.
2) Check ink form roller-to-plate pressure.
3) Check plate cylinder-to-blanket cylinder pressure.
4) Check impression adjustment (squeeze).