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Jürgen Gemeinhardt

Jürgen Gemeinhardt

Head of department
Printing techniques

E-mail
gemeinhardt
transparent 11x15@fogra.org

Telephone
+49 89. 431 82 - 256


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Current research projects (in the field "conventional printing technologies")

32.169
Reduction of 'Picture Framing' in sheet-fed offset printing through the appropriate choice of materials and application parameters

Timescale: 01.01.2016 to 31.12.2017
Funding:
Programme of the Federal Ministry of Economic Affairs and Energy for the support of "Industrielle Gemeinschaftsforschung (IGF)" via the German Federation of Industrial Research Associations (AiF)

Deposits outside the paper format, frequently referred to as 'Picture Framing', are now a problem for many sheet-fed offset printing companies. These particles can lead to an unwanted build-up on the blanket as well as on the impression cylinder, and the wash-up cycles that this makes necessary have a significant impact on the viability of print production. However, to date, there have been no suitable proposed solutions or preventive measures. Affected printers therefore have no alternative but to resort a process of individual trial and error in order to discover the best combinations of materials and press settings.
The aim of this research project is to achieve a better understanding of the mechanisms that lead to 'Picture Framing' and to draw up specific remedies by identifying and quantifying the parameters that have a significant influence. Particular attention will be paid to the damping budget, which will be checked for the first time in detail to see if it is correlated in any way with the phenomenon. The starting assumption is that this will be a key quantity both in relation to the occurrence and also the possible reduction of such disruptive build-up.

 

42.028
Modelling quantitative parameters in sheetfed offset printing on the basis of measurable paper properties

Timescale: 01.02.2016 to 30.04.2018
Funding:
Programme of the Federal Ministry of Economic Affairs and Energy for the support of "Industrielle Gemeinschaftsforschung (IGF)" via the German Federation of Industrial Research Associations (AiF)
Partner: Bundesverband Druck und Medien e.V.

This research project is intended to precisely identify the paper-related properties that influence solid colouring and tone value increase and for these to then be submitted as a proposal for adoption in ISO 15397. This standard specifies the paper properties to be communicated between manufacturers and printers and therefore offers one way of monitoring incoming materials so that potential printing problems can be picked up in advance. Quantifying the interrelationships should also make it possible to adopt appropriate press pre-sets for solid colouring and to make suitable adjustments to the tone value increase in the CTP RIP for the paper that is being used.
Results obtained as part of the planned research project should also make clear the extent to which it is possible to assign special substrates such as board, bulky papers or uncoated grades with compressed and smooth surfaces to the pre-existing types of paper. The key criterion for this will be the ability to achieve the specified solid colouring using typical offset printing ink layer thicknesses, whilst deviating tone value increase could be corrected for in practice in the RIP by means of the new algorithms that will be determined. It is possible that additional paper categories may need to be defined, and these could be introduced into the standardization process as a proposed amendment. The classification should be based on the properties of the materials that are found to be responsible for the achievable solid densities.

 

80.008
The foundations for graphic standardization in the manufacture of plastic cards

Timescale: 01.04.2015 to 30.09.2017
Funding:
Programme of the Federal Ministry of Economic Affairs and Energy for the support of "Industrielle Gemeinschaftsforschung (IGF)" via the German Federation of Industrial Research Associations (AiF)

ISO 12647-2 governs the process colour (CMYK) solid colourings, tone value increases and tolerances in offset printing. It is supplemented by ProcessStandard Offset (PSO), which has been developed by the Bundesverband Druck und Medien e.V. (German Printing and Media Industries Federation) and Fogra. The latter describes an industrialized and standardized procedure for the production of printed matter in accordance with ISO 12647-2. ProcessStandard Offset allows production quality to be assured from data capture right up to the finished print. Printing processes are monitored, controlled and checked using suitable means for testing and monitoring methods, such as colour and density measurement devices and appropriate test elements (eg. control strips). However, ISO 12647-2 and ProcessStandard Offset only cover paper as a substrate. For some time, the international standards committee that is responsible for 'plastic cards', ISO/IEC JTC 1/SC 17 WG1 ('Cards and Personal Identification') has also been discussing guidelines for colour values and tolerances on plastic cards. However, proposals for further work resulting in definitive data sets have been suspended due to the lack of the basic information required for these discussions.
Previous investigations showed that with matt core films there were no film-related differences in the tone value transfer on the core films, prints on glossy core films exhibit tone value increases that are ca. 5% less, the colour location of the core films has an impact on the colour location of the prints and that as a result of the lamination the tone value increases by up to 10 % and colour changes of up to ΔE*ab = 8 occur. Current investigations confirm these underlying effects for the laminates and furthermore make clear the influence of the measurement aperture of the colour measurement device on the colour locations. Colour measurement results obtained with a measurement device with an 11 mm measurement aperture, served as the basis for an initial standardization proposal, but this still lacked a statistical validation. On the basis of colour measurements made with large measurement apertures, colour shifts between prints and laminates appear to be relatively uniform and the compensation undertaken should be material independent.
On the other hand, when colour measurement data are obtained using colour measurement devices that are typical of the printing industry (apertures < 4 mm) there are apparently clear differences in the quantitative colour characterizations for different combinations of core and overlay films.
These differing results are probably largely due to differences in the lateral spread of the reflected light within the transparent overlay.
In order to render small aperture colour measurement devices, which are already widely distributed in the printing industry, usable for the colour characterization of laminated cards, it would be desirable to be able to simulate the measurements for large apertures from the measurements obtained using small apertures. In order to do so the ways in which such key characteristics of the overlay film as refractive index, absorption behaviour, thickness and roughness, the core film roughness and the roughness of the interface between overlay and core films influence small aperture colour measurements should be determined and then incorporated into a simulation method.
A further, more detailed understanding of colour changes with ageing would be very helpful for assessing the usable lifespan of cards.

Contact: Dr. Uwe Bertholdt



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