CTP acceptance

The current situation

The high investment costs of CtP systems can only be justified when they are able to offer trouble-free, economical and high quality production. For this to be so, all the components of these complex systems – plates, setter, processor, pre-heater (in some cases) and so on – must be optimally suited to each other. Achieving this is no simple task, especially if the system is not a complete solution from a single supplier or when some staff lack CtP experience.

Demands

When advising printers it often transpires that all that exists is a set of technical specifications with some performance data, but no overall concept. The imaging quality to be produced by the CtP system will therefore only be recorded on the basis of a job or a test forme from the system manufacturer and visually assessed using subjective criteria. In very few cases will it be measured. When, in the course of time, flaws arise in the transmission quality there is no clean, objective and quantitative documentation of the output standard, and clear evidence is then difficult if not impossible to obtain.

Technical acceptance of the CtP system

It therefore makes sense to arrange for a neutral body such as Fogra to carry out a technical acceptance of the CtP system that involves quantitative measurements of its performance. Following a start up phase after installation of around 2 to 3 weeks the actual technical condition is recorded. The Fogra acceptance checks look first of all at focusing and spot size, followed by register checks, with and without plate changes. In order to ensure uniform image quality, it is important that the system is capable of achieving a high degree of consistency, both spatially and over time, across the entire tonal range.

New guidelines for the technical commissioning of CtP systems

The Fogra CtP acceptance test is a technical procedure based on measurements and evaluations of established control elements and test forms. In 2005, the applicable methods, target values and tolerances were officially published by the German Printing And Media Industries Federation in the “Leitfaden zur Abnahme von CtP-Anlagen” (guidelines for the technical commissioning of CtP systems).
In order to account for newer technologies like photopolymer, ablative and process less plates as well as computer to conventional plate systems, Fogra conducted a research project in 2007 to revise and amend the existing guidelines. The revision proofed necessary, in order to satisfy the increasing demands of the printing industry. Furthermore, the diverse CtP technologies sometimes need different methods and tolerances for examination and evaluation.
The new “Richtlinien zur Abnahme von CtP-Anlagen” (Praxis Report No. 80) are expected to be published in August 2008 by Fogra. In agreement with German Printing And Media Industries Federation, the „Leitfaden zur Abnahme von CtP-Anlagen“ will be replaced by the new guidelines published by Fogra.

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Information sheet