Heidelberg CD74 ink rollers question

Discussion in 'Heidelberg Printing Presses' started by IvoDobrev, Mar 3, 2023.

  1. IvoDobrev

    IvoDobrev New Member

    Joined:
    Mar 2023
    Messages:
    1
    Location:
    Bulgaria
    Hello Dear printers,
    I'm trying to decide, does we have to change with new one the inking unit rollers of the machine.
    What is the "typical" time period between replacements of the rollers?
    Unfortunately the operators of the printing press have two different opinions.
    The rollers are with good looking surface without any cracks.
    What we have to check just to be sure.
    Is it recommended to measure the hardness of the gum surface or we have to check the diameters according to the manual?
    What should be the difference?
     
  2. Jack liston

    Jack liston Senior Member

    Joined:
    Sep 2019
    Messages:
    346
    Location:
    Connecticut
    You need to check the roller stripes if you can not maintain the setting you must change/ if rollers are to hard you will have water and ink issues.
     
  3. turbotom1052

    turbotom1052 Senior Member

    Joined:
    Oct 2008
    Messages:
    1,111
    Location:
    Vermont
    Besides checking for the obvious cracks, you should also be looking to be sure the roller diameters are within spec. It's not uncommon for rollers if not set properly to swell on the ends. If the ends are of a larger diameter than the center you might consider monitoring that going forward. Then as mentioned by Jack you will want to check the hardness of the rollers. This is known as durometer. They make a gauge thats used to measure the durometer of rollers. If the rollers durometer is out of spec you will have problems.
     
  4. mrheidelberg

    mrheidelberg Senior Member

    Joined:
    Jan 2008
    Messages:
    761
    Location:
    United Kingdom
    In the UK this is known as shore hardness, with the instrument to measure known as a Durometer.
     
    asem alsafady likes this.

  5. Adil

    Adil Senior Member

    Joined:
    Nov 2021
    Messages:
    1,383
    Location:
    Casablanca
    Hi sor

    the points to be checked on the caoutchouc offset rollers are the hardness in shore degrees (generally the dampening rollers must have a hardness of 25°shore and the inking rollers must have a hardness of 30°shore) also it is necessary to control the diameter of the roller according to the catalog and the appearance of the rubber they must not be glossy (smooth)
    Good luck
     
Loading...