Model-Based Ink Key Presetting for Offset Presses.

The purpose of this study is to develop an ink key presetting system which can analytically preset ink keys and ratchets and can thus greatly shorten the make-ready time. A steady-state inking system model, comprising the roller train, vibrator, overall system gain, and density-thickness relationship, was developed for this purpose. In the presetting process, the plate coverage is first estimated from a digital plate file or a plate scanner. Via the inking system model, ink key openings are further estimated. Finally, ink keys and ratchets are set automatically through an electronic interface. In addition to being a standalone tool, this presetting system will be used to provide the initial settings and ink consumption information for an on-going closed-loop color control project.