Journal of Print and Media Technology Research

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

2025-06-30T18:48:02+00:00

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.

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

2025-06-30T19:00:24+00:00

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.

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

2025-06-30T19:09:14+00:00

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.