Heidelberg CD74 ink rollers question

[IvoDobrev]

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?

 

[Jack liston]

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.

 

[turbotom1052]

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.

 

[mrheidelberg]

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.

In the UK this is known as shore hardness, with the instrument to measure known as a Durometer.

 

[Adil]

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