The Typical Inking System

At the heart of most large sheetfed presses lies the inking system, or inker. This critical assembly, typically comprising at least ten rollers, precisely meters and transfers ink to the printing plate. Its primary components are detailed below and illustrated in Figure 3-7.

Ink fountain - This pan holds the ink supply.

Ductor or ductor roller - A transfer roller that moves alternately between contacting the ink fountain roller and the first roller of the inking system, which is often an oscillator.

Oscillators or vibrators - These gear- or chain-driven rollers perform two motions: rotation and side-to-side oscillation. This action distributes and smoothes the ink while erasing image patterns from the form roller.

Intermediate rollers - Positioned between the ductor and form roller, these friction- or gravity-driven (surface-driven) rollers transfer and condition the ink. They are often termed distributors if contacting two rollers, or riders if contacting a single roller like an oscillator.

Form rollers - A set of three to four rollers, usually of differing diameters, that directly contact the printing plate to transfer ink onto it.

The entire series of rollers, excluding the ink fountain and fountain roller, is collectively known as the roller train. This train consists of alternating hard and soft rollers. Hard rollers are typically steel covered with copper, ebonite, or nylon. Resilient rollers—including the ductor, intermediate, and form rollers—are frequently constructed from synthetic rubber compounds like PVC (polyvinyl chloride), Buna-N (a copolymer of butadiene and acrylonitrile), or polyurethane. These materials are applied to a steel shaft.

This integration supports broader industry goals of reducing waste and enhancing automation in the pressroom.