The between color deck dryers play an intricate part of the printing process that are often overlooked and improperly maintained. If the dryers are not properly balanced and maintained this can lead to excessive waste and machine downtime. With the dryers being improperly balanced it can lead to dirty print, premature "staining" of anilox rolls, ghosting, trapping problems and the reduction of solvent capture to name a few.
In an effort to reduce these potential issues, here are some recommended preventative maintenance guidelines:
- Make a complete inspection of the blower units paying close attention to belts, proper lubrication and any debris inside the motor cage that can be removed.
- Some presses have a central screen collection catch where as the screen and or screens should be removed and properly cleaned.
- A few of the older model printing presses will have a screen built in the exhaust hose, and in some cases can only be seen by shining a flashlight down the supply hose. This screen should be removed, properly cleaned and reinstalled.
- The between color dryer barrels should be removed from the press, paying close attention not to damage any equipment such as the central impression drum, anilox rolls or printing cylinders.
- As each dryer is removed from the press, a number to reference the placement of the dryer should be punched in the dryer to ensure the dryer is reinstalled in the same deck it was removed from.
- Once the dryer is removed it should be properly cleaned to make sure all the vent holes are free of any debris and ink. Pay close attention to the ends of the dryers. Any ink build up can cause web breaks as well as wear on the central impression drum. Once this is achieved the dryers can be reinstalled.
- Each between color dryer hose should be inspected for holes, ink and debris built up inside the hose. Replace the hoses as necessary; this is inexpensive due to the fact most between color dryer hoses are short in length.
- The between color dryer baffle adjustments should have an arrow to indicate what direction is closed and open.
- Once all the above is achieved, the outfeed exhaust baffle should be completely opened. One person with a smoke stick or smoke gun should slowly move the smoke from one end of the dryer to the other while a second person slowly opens the air intake baffle until the smoke starts exhausting through the between color dryer. Once this is achieved, mark the baffle adjustments to each dryer and tighten down. This will give you a reference as to where you had them adjusted in case the adjusters are moved.
- Keep in mind that too much exhausting will create negative airflow around the printing deck area.
- In an effort to reduce valuable press downtime and print defects, this procedure should be implemented on a preventative maintenance schedule.