June 2025

Download the full issue: 4-24

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Daniel Bohn

EDITOR-IN-CHIEF

The news section of the Journal: Topicalities

Click on titles to download full articles:

Development of a 3D-formed and thin-film backlit HMI

Gunter Huebner,Katrin Mayer, Wolfgang Kaefer and Klaus Schmidt

E-mails: huebner@hdm-stuttgart.de, mayerkatrin243@gmail.com, wolfgang.kaefer@marquardt.com, klaus.schmidt@motherson.com

Institut für Innovative Anwendungen der Drucktechnologien (IAD),
Hochschule der Medien, Nobelstr. 10, 70569 Stuttgart, Germany

Marquardt GmbH,
Schlossstr. 16, 78604 Rietheim-Weilheim, Germany

Motherson DRSC Deutschland GmbH,
Lindenstrasse 10-12, 96317 Kronach-Neuses, Germany

Abstract

During three subsequent research projects in co-operation with industrial partners, thin printed touch sensors were developed and investigated. In the first project the touch sensors employing the capacitive or piezoelectric principle were screen-printed as thin-film sheets of transparent polycarbonate. In the second project, these thin-film sheets were 3D-formed through thermoforming and over-moulding process. In the third project, a thin-film light source was printed onto the backside of the transparent sensors. The backlighting was achieved using either electroluminescence or an innovative technique of micro-LEDs suspended in a printed varnish, a proprietary method developed by the company NthDegree.

Keywords: screen-printing micro-LED lighting touch sensors Human Machine Interface (HMI) 3D forming

JPMTR-2411 Research paper | 195
DOI 10.14622/JPMTR-2411
UDC 621.395.623:621.383.8

 

Received: 2024-09-23
Accepted: 2025-02-19

 

Optimization and forecasting models of the sublimation printing process on textile materials

Vyacheslav Repeta, Yurii Petriv and Yurii Kukura

Emails:  viacheslav.b.repeta@lpnu.uayurii.a.kukura@lpnu.ua yurii.i.petriv@lpnu.ua

Institute of Printing Art and Media Technologies, 
Lviv Polytechnic National University, 
Ukraine, Lviv, Bandera St., 12, 79013 

Abstract

The paper presents the results of the analysis of the sublimation printing process on fabrics by the Taguchi method and forecasting the process quality using the fuzz y logic principles. Imprints obtained in different technological modes and on textiles with different absorbency. Based on the results of the analysis, it was established that the temperature and the material absorption capacity have the greatest influence on the optical density of imprints. Using the Taguchi method it was determined that the optimal parameters of the printing process to achieve high optical density are the material moving speed of 18 m/h, the temperature of the printing process of 215 °C and the textile absorption of 19 mm. Taking into account that the influence of the material moving speed in the range of 18–32 m/h showed to be insignificant, two factors were selected to forecast the process quality: the temperature and the material absorption capacity. The formed fuzz y knowledge base made it possible to construct forecasting models of the influence of these two factors on CMYK ink printing process quality. The comparison of the simulated values of optical density with the values that were obtained experimentally shows the adequacy of the models for CMK colours. Significantly higher optical density deviations are observed for the yellow colour (Y), which indicates a less controlled thermal transferprocess. This is also indicated by the value of the signal-to-noise ratio, which is minimal for yellow.

Keywords: sublimation printing process factors optimization Taguchi method fuzzy logic forecasting model

JPMTR-2413 Review paper | 196
DOI 10.14622/JPMTR-2413
UDC 677.84:655.39:658.562:519.22:519.87:004.822 (045)

Received: 2024-01-18
Accepted: 2025-01-29

 

Separating the effects of maximum pressure and printing nip length on flexographic print quality

Cecilia Rydefalk, Sofia Thorman, Anton Hagman  and Artem Kulachenko 

Emails: rydefalk@kth.se

Department of Engineering Mechanics,
KTH Royal Institute of Technology, Sweden

Department of Sustainable Materials & Packaging,
RISE Research Institutes of Sweden, Sweden

 

Abstract

When adjusting the impression in a printing press both the maximum pressure induced and the contact length between the print form and the substrate are simultaneously altered. In the present study, lab printing was performed with controlled load cases. The load cases were chosen to achieve varying nip lengths or maximum pressure. A lab-scale printing press was augmented with a pressure sensor that measures the width of the print over a square area. By altering the print forms and the force settings in the machine, the print nip pressure pulse was controlled. Printing was performed in both solid tone and halftone, and the printed result was evaluated for mottle, density, and dot-gain. By increasing the maximum pressure, the color density increases. By increasing the nip length at a fixed maximum pressure, the color density decreases. The variation within the settings in the present study is small and appears to originate from the split pattern. The change in the nip exit angle with increased nip length is sufficient to alter the ink split point and, thereby, the density. A higher maximum pressure can instead enable a higher ink transfer.

Keywords: flexography, lab printing, mottle, print density, ink transfer

JPMTR-2415 Original scientific paper | 197
DOI 10.14622/JPMTR-2415 
UDC 677.84:655.39:658.562:519.22:519.87:004.822 (045)

Received: 2025-01-08
Accepted: 2025-04-17