The ink and dampening roller train is the circulatory system of a sheetfed press — and the easiest area to disguise on a used machine: rubber rollers can be reground, chrome surfaces hide scratches, and intermediate-roller aging is invisible at first glance. Anchor the inspection on three things — diameter, color code and surface material — and use the classic Heidelberg CD102/SM102 roller configuration as the reference. Ten minutes is enough to expose a roller train that has been swapped or worn past its life: 19 rollers in the ink train, 5 in the dampening train, each with a checkable identity.
- Ink train: 15 numbered rollers, of which 4 are plate-contacting ink form rollers — No.1 φ60 mm white, No.2 φ72 mm blue, No.3 φ66 mm red, No.4 φ80 mm yellow, all rubber; outside the main line sit 4 more φ85 mm polyamide rollers.
- Dampening train, five rollers in series: water pan roller φ108 mm (rubber) → metering roller φ98 mm (chrome-plated) → intermediate roller φ56 mm (polyamide) → form dampening roller φ78 mm (rubber) → oscillating roller φ85.1 mm (rough chrome surface).
- Material means function: rubber surfaces transfer ink and water and touch the plate, chrome surfaces meter the film, polyamide rollers only bridge intermediate positions and never contact the plate.
- Three inspection moves: measure diameters with a caliper, match color codes to positions to catch swaps, and rake both chrome surfaces under a light for scratches while checking rubber for glazing and cracks.
Color code plus diameter: the first line of roller identity
The white, blue, red and yellow rings on the ink form rollers are an assembly identity system: all four diameters differ (φ60/72/66/80 mm) and pair one-to-one with a color, so a misplaced or substituted roller gives itself away on the spot. A diameter clearly below nominal means repeated regrinding or overall aging; a faded or re-glued color ring is a warning that rollers may have been shuffled.
The dampening five: chrome surfaces decide water-film uniformity
The φ108 mm pan roller picks up solution from the tray, the φ98 mm chrome metering roller sets the film thickness, the φ85.1 mm rough-chrome oscillating roller distributes it across the width, and the φ78 mm rubber form roller lays it onto the plate. Inspect both chrome surfaces under a raking light: scratches, rust spots or impact dents on the metering or oscillating roller break film uniformity at once — the print shows scumming or weak, washed-out plates — and such damage cannot be serviced away, only re-rollered.
Polyamide intermediates: the hidden wear nobody checks
The φ56 mm and φ68 mm ink transfer rollers and the φ56 mm dampening intermediate roller are all polyamide. They never touch the plate, so their aging goes unnoticed — yet once the surface yellows, glazes and loses its wetting balance, ink-water balance keeps drifting: scumming soon after wash-up, weak color the moment water is increased. Wipe with a white cloth and feel by hand; slipping or powdering intermediates belong in the re-roller budget.
Bottom line: roller-train inspection is not black magic — color code matches position, diameter matches nominal, chrome free of scratches, rubber free of glazing and cracks, intermediates not aged. Run these five checks and the true condition of the ink and water system is on the table, which is exactly the leverage you need in price talks.
