Ink Fountain Metering - Ball Movement?

SteveSuffRIT

Well-known member
Hi Industry, educator wanting to correctly inform students (terms & definitions) about different types of press ink metering systems, mostly for sheetfed offset litho. I know some webs, like coldset newspaper are ductorless.
Specifically, would like to create a list showing how global ink sweep or stroke is achieved for different presses (Heide, Komori, KBA, Manroland, etc).
On our Ryobi 2800 & 3200 (~AB Dick) duplicators, ball roller is intermittent and adjustable distance, the ductor is fixed.
For "real" production presses does ink fountain ball roller spin continuously or intermittently?
How is the contact dwell time being adjusted, by the ball or the ductor?
What is being adjusted, turning stroke speed/time or distance?
What is normal/typical ductor cycle, 1:1, 2:1 (normal), adjustable to X:1 for light area plate coverage?
Is preference for less blade keys and more ball/ductor sweep?
 

alibryan

Well-known member
Q) For production presses does ink fountain ball roller spin continuously or intermittently?
A) Modern presses are continuous
Q) How is the contact dwell time being adjusted, by the ball or the ductor?
A) Dwell (contact) time isn’t adjustable. The amount of ink picked up is determined by the speed of the ball when ductor is in contact with it (length of stroke).
Q) What is normal/typical ductor cycle, 1:1, 2:1 (normal), adjustable to X:1 for light area plate coverage?
A) 3 sheets per duct (3:1) but may be adjustable up to 30 sheets per duct.
Q) Is preference for less blade keys and more ball/ductor sweep?
A) Operator preference. But with modern press software, typically the ball speed is predetermined and ink keys move to match image requirements.
 

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