Nip pressure

[sornchai]

Hello,
I have a question about adjusting nip pressure of the inking roller and the dampening roller. Between chrome roller and rubber roller in the dampening if roller nip is bigger than specification , will it transferred more water than smaller nip ? Between fiber roller and rubber roller in the inking if the roller nip is bigger than specification , will it transferred more ink than smaller nip?
Sorry for my english

 

[SteveSuffRIT]

Wider strip is more pressure.
More pressure is less transfer between nip.
What is "Fiber" roller? It's not a molleton cotton cloth?
Do you have a diagram of rollers to show?

 

[Cornishpastythighs]

Always keep an eye on your rubber roller Durometer as this will affect the metering of water through the nip

 

[sornchai]

Wider strip is more pressure.
More pressure is less transfer between nip.
What is "Fiber" roller? It's not a molleton cotton cloth?
Do you have a diagram of rollers to show?

Thank you Steve. Fiber roller is rilsan so more pressure between rilsan and rubber be less transfer?

 

[SteveSuffRIT]

I'm not familiar with a "fiber" rilsan roller?
In my earlier reply, I thought you might have an old style cotton cloth molleton roller or paper sleeve in the dampener?
The only rough texture (fiber) rollers I know are soft rubber, like a "Hickey Picker" form roller.
Regardless, to answer your original post question, I would reduce the water feed rate to make the nonimage areas of plate print dirty (dry-up, catchup), stop, then make your roller pressure adjustment. If on restarting, the plate now cleans up, that adjustment provided more water.

 

[smalloffsetpressexperts]

A Rilsan roller (also called a Rilsan-coated roller) is a specialized industrial roller used primarily in offset printing presses. It consists of a metal core coated with Rilsan®, a high-performance polyamide 11 (PA11) polymer powder that's thermally fused to the surface, creating a tough, durable protective layer.Key Features and BenefitsMaterial: Rilsan is a bio-based nylon derived from castor oil, trademarked by Arkema. It's applied as a fine powder and fused for a hard-wearing coating (typically 1–2.5 mm thick).
Common uses: In ink distribution, oscillation (vibration), or transfer rollers on machines from manufacturers like Heidelberg, MAN Roland, Komori, and Goss. These rollers often replace older copper-, chrome-, ebonite-, or rubber-coated versions.
Advantages:Exceptional resistance to abrasion, wear, friction, corrosion, inks, solvents, chemicals, and high temperatures.

 

[Cornishpastythighs]

A Rilsan roller (also called a Rilsan-coated roller) is a specialized industrial roller used primarily in offset printing presses. It consists of a metal core coated with Rilsan®, a high-performance polyamide 11 (PA11) polymer powder that's thermally fused to the surface, creating a tough, durable protective layer.Key Features and BenefitsMaterial: Rilsan is a bio-based nylon derived from castor oil, trademarked by Arkema. It's applied as a fine powder and fused for a hard-wearing coating (typically 1–2.5 mm thick).
Common uses: In ink distribution, oscillation (vibration), or transfer rollers on machines from manufacturers like Heidelberg, MAN Roland, Komori, and Goss. These rollers often replace older copper-, chrome-, ebonite-, or rubber-coated versions.
Advantages:Exceptional resistance to abrasion, wear, friction, corrosion, inks, solvents, chemicals, and high temperatures.

No experience of using Rilsan in a Dampening unit, have used mainly Ceramic or Chrome. Have used Rilsan a lot in the inking system as a distributor roller. We switched to Ebonite as Rilsan was very expensive and took a long time to turnaround and Ebonite recovering could be obtained locally, we found Ebonite to be a good substitute.

 

[SheetSqueezer]

Rubber ink rollers to ink distributor roller (any material) = 4mm - 5mm
Rubber ink rollers to plate = 3mm - 5mm but always slightly less than distributor roller setting
Rubber damp rollers to damp distributor roller (any material) = 3mm - 5mm
Rubber damp rollers to plate = 4mm - 6mm and most don’t need to be less than distributor roller setting as they are usually gear driven.

Refer to operator’s manual for recommended individual roller settings throughout but some slight (experienced) adjustment to those can be used, if/when necessary.

A thicker nip can sometimes reduce transfer but helps when there is swelling on ends or roller is not uniform across. A thinner nip (as long as there is enough) can sometimes help transfer but roller needs to be uniform across.

 

[smalloffsetpressexperts]

Rollers in the dampening unit (blue rollers in the inking unit diagram):
Various roller materials are used in the dampening unit. The dip roller (purple) and the dampening roller are coated with rubber, the metering roller (dark blue) is coated with chrome, and the remaining dampening rollers can be coated with chrome, rubber, and/or Rilsan. All dampening rollers are designed to be water-friendly.
Is this a coater?

 

[SteveSuffRIT]

Was last post supposed to include a color-coded graphic of rollers?
I'm still confused about original post using the term "fiber" roller?
I assume it meant "textured" finish, not the composition material.

 

[smalloffsetpressexperts]

Sorry my bad it was a cut/paste text with a small diagram. I was pointing out the many types of dampening system's.
Why not send a jpg or png of the roller that has us all baffled