Why ink rollers need to be set to spec, and other tales from the pressroom
Kevin Gossett, plant manager of the Monroe Publishing Co. in Monroe, MI, shares the reason ink rollers need to be set to certain specifications and the roller’s function in the water or ink train: “
Ink transfer rollers do more than their name implies. Located between or just on an oscillator roller, the transfer roller is doing the final milling and emulsifying of the ink before it is applied to the plate. Transfer rollers should be set to press manufacturers’ specifications, which is a thinner line than form rollers because it is a smaller roller. Setting this roller to the spec allow the ink to better mill and also allows the roller to transfer the ink without acting as a squeegee.
Form rollers, both ink and water, need to have a slightly heavier stripe to the plate so that the cylinder is driving the roller instead of the oscillator, therefore allowing the rollers to turn at the same speed as the cylinder and slip against the oscillator. If you observe strange marks in solids, check the stripping of all forms in contact with that cylinder. You could be observing roller drag due to tighter contact to the oscillator.
The same holds true with the sock roller adjustment to oscillator and water pan roller. You want the oscillator to drive the sock roller instead of the water pan roller. The pressure applied to both is crucial so that the solution is fed at an even rate to the water form. Too tight and the solution is squeezed off and too loose will not provide the uniform film required for proper ink/water balance.
If a roller is too hard you can forget about setting the proper stripe widths and the roller performing to expectations. The harder the roller, the more pressure that has to be applied to get the desired stripe. At this point it is time to replace the roller because it will not transfer to deliver the ink or water required. A hard form roller will also cause toning and tinting and wear out printing plates prematurely.”
Thanks for the advice, Kevin.