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Gorazd Golob

Editor-in-chief
gorazd.golob@jpmtr.org

The news section of the Journal: Topicalities

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Heightmap-based computing of the tool gap for additive manufacturing of paper embossing tools

Jakob Feldmann¹, Dieter Spiehl¹, Edgar Dörsam¹ and Andreas Blaeser²

E-mails: feldmann@idd.tu-darmstadt.de; spiehl@idd.tu-darmstadt.de; doersam@idd.tu-darmstadt.de; blaeser@idd.tu-darmstadt.de 

¹Technical University of Darmstadt, Department of Mechanical and Process Engineering, Institute of Printing Science and Technology, Magdalenenstr. 2, 64289 Darmstadt, Germany

²Technical University of Darmstadt, Department of Mechanical and Process Engineering, Institute for BioMedical Printing Technology, Magdalenenstr. 2, 64289 Darmstadt, Germany 

Abstract

Tools used for embossing paper and cardboard usually consist of two dies, which are inverses of each other. An important design parameter is represented by a defined gap between the fully closed dies. This is achieved by creating one of the two dies with an embossing relief that is displaced by a constant surface-normal offset. To facilitate fast data preparation for additive manufacturing of such embossing tools, a heightmap-based image data processing is developed, although the preparatory steps and resulting data may be also used for conventional manufacturing. The fundamentals of paper embossing tool layout and relief representation in heightmap images are explained and the developed process steps and their calculation bases are discussed. The focus is placed on the derivation of a heightmap with constant normal offset with respect to an input heightmap. For this purpose, image processing algorithms are elucidated to first determine the relief’s surface curvature and use this information to deduce the necessary alteration to receive a derived heightmap. The generated data is reviewed and evaluated regarding its suitability for the production of additively manufactured embossing tools, which is done by examining the data as well as the derived physical dies. 

Keywords: 3D printing, stereolithography, image processing, heightmaps, direct tooling

JPMTR-2204 Original scientific paper | 164
DOI  10.14622/JPMTR-2204
UDC 676.8|7.022-022.4|51-3 

 Received: 2022-03-22
Accepted: 2022-07-15

Use of Bacillus subtilis spores in printing and additive manufacturing as a robust, DNA-based anti-counterfeiting and identification feature: stresses, processing and evaluation

Philipp Wüst¹, Thomas S. Dohmen², Alexander Waal¹, Dieter Spiehl¹, Edgar Dörsam¹, Andreas Blaeser³,⁴ and Johannes Kabisch⁵ 

E-mails: wuest@idd.tu-darmstadt.de; spiehl@idd.tu-darmstadt.de; doersam@idd.tu-darmstadt.de; blaeser@idd.tu-darmstadt.de; johannes.kabisch@ntnu.no 

¹Technical University of Darmstadt, Department of Mechanical and Process Engineering, Institute of Printing Science and Technology, Magdalenenstr. 2, 64289 Darmstadt, Germany  

²Technical University of Darmstadt, Department of Biology, Computer-aided Synthetic Biology, Schnittspahnstr. 12, 64287 Darmstadt, Germany

³Technical University of Darmstadt, Department of Mechanical Engineering, Institute for BioMedical Printing Technology, Magdalenenstr. 2, 64289 Darmstadt, Germany

⁴Technical University of Darmstadt, Centre of Synthetic Biology, Schnittspahnstr. 10, 64287 Darmstadt, Germany

⁵Norwegian University of Science and Technology, Department of Biotechnology and Food Science, Kjemi 3, Gløshaugen, Sem Sælands vei 6, 7034 Trondheim, Norway 

Abstract

Part labeling is a crucial security feature as it can prevent product counterfeiting. Deoxyribonucleic acid (DNA), the information carrier of life, is started to be explored as an engineered information molecule with immense potential in respect to information density and encryption. Most research in this direction is concerned with how to encode binary data into DNA and read the stored information from this DNA. Little to no effort is made on how to apply DNA and the information stored within as an identification label for counterfeit protection. In this study, we explore DNA in various printing processes for its suitability as an anti‑counterfeiting and identification tag. DNA is sensitive to environmental influences, which is why we compare the suitability of free DNA against using the spores of the bacterium Bacillus subtilis as a naturally evolved DNA protective shell. To integrate these two DNA species into products, we aim to use both conventional printing methods and additive manufacturing processes. Foremost we investigate the stresses on the DNA as well as spores, then derive suitable printing techniques and assess the practical application – processing, extraction and subsequent detection via polymerase chain reaction (PCR). The stresses are differentiated into four groups – solvents, UV irradiation, temperature and shear stress, to which both DNA species are exposed and characterized. In actual printing processes several kinds of stresses are combined and thus we test two exemplary and complementary methods. Namely gravure printing as a conventional 2D– and masked stereolithography as a 3D printing method. We were able to show that both free DNA as well as DNA encapsulated in spores can be readily integrated into printing processes and detected using PCR where there are some significant advantages for DNA protected in spores. Consequently, spores, which can be applied economically, fast and in large quantities using printing, offer great potential for counterfeit protection, for example on drug packaging.

Keywords: gravure printing, 3D printing, masked stereolithography, product piracy, counterfeit protection

JPMTR-2214 Original scientific paper | 165
DOI  10.14622/JPMTR-2214
UDC 655.1:582.2-577.2:343.5 

Received: 2021-06-14
Accepted: 2022-09-02

Characterizing the influence of white ink coating weight and print layer film type on chromaticity in gravure printed flexible packaging

Robert J. Eller and Gregory S. D’Amico 

E-mails: rjeppr@rit.edu; gdsppr@rit.edu 

Department of Packaging and Graphic Media Science, Rochester Institute of Technology, 69 Lomb Memorial Drive, Rochester, NY 14623 

Abstract

When printing transparent substrates, a white ink underlayer is frequently required to reproduce saturated colors. Nevertheless, the cost of adding this underlayer makes it a potentially attractive cost reduction opportunity. The primary objective of this study was to investigate the influence of white underlayer coating weight (g/m²) and print layer film type on the chromaticity of reverse printed structures representative of those found in gravure printed flexible packaging. To analyze the influence of white ink coating weight (Ctg Wt) and print layer film type on chromaticity, six design of experiments (DOEs) were conducted. Each DOE explored the relationship between three levels of white ink coating weight and three print layer film types for one ink (Magenta, Cyan, Yellow, Orange, Violet, or Black). The DOE results showed that both coating weight and film type have a statistically significant effect on chromaticity (P < 0.005). For Magenta, Cyan, Yellow and Orange inks, white underlayer coating weight had the dominant effect on chroma (the values of ΔC*_ab typically between 4 and 7) while the effect of print layer film type was relatively minor (the value of ΔC*_ab is typically < 1). For Violet ink, white ink Ctg Wt was still the dominant effect (the value of ΔC*_ab was 7), but print layer film type had a more pronounced effect (the value of ΔC*_ab was 3). The relationship between coating weight and chroma over the range from 0.49 g/m² to 1.95 g/m² was linear for all inks (R2 > 0.99). Finally, when printing Magenta, Cyan, or Orange ink a coating weight reduction of 1 g/m² (from 1.95 g/m² to 0.98 g/m²) resulted in a color shift of the ΔE₀₀ ~2.5, and a 1.5 g/m² reduction (from 1.95 g/m² to 0.49 g/m²) resulted in a color shift of ΔE₀₀ ~3.5. Yellow, the weakest ink, was more affected (the ΔE₀₀ ~4 for 1 g/m², and ΔE₀₀ ~5 for 1.5 g/m²), while Violet, a hue where the human visual system has less sensitivity to chroma differences, was less affected (the ΔE₀₀ ~1.5 for 1 g/m², and ΔE₀₀ ~2 for 1.5 g/m²). For achromatic Black ink, lightness (L*) was chosen as the response variable. Although white ink Ctg Wt and print layer film type had statistically significant effects on L*, the differences attributable to these effects were at or below the threshold of visual detection. 

Keywords: white ink underlayer, color saturation, ΔE₀₀, rotogravure

JPMTR-2212 Research paper | 166
DOI  10.14622/JPMTR-2212
UDC 762:774.8-035.67-026.61 

Received: 2022-06-03
Accepted: 2022-07-20

Authentification of Indian paper currency using digital image processing

Sonia Sarkar and Arun Kiran Pal 

E-mails: sonia140897@gmail.com; arunkiranpal@gmail.com 

Department of Printing Engineering, Jadavpur University, Salt Lake Campus, Block-LB, Plot-8, Sector-III, Salt Lake, Kolkata-700106, India 

Abstract

Counterfeit currency notes create serious threat to the economy as it reduces the value of genuine currency and ham-pers the financial system due to inflation. Hence to limit the circulation of fake currency notes a system needs to be designed which can authenticate a banknote more efficiently. The aim of this present investigation is to differentiate between real and fake currency notes by considering various elements of digital image processing (IP). This methodology when applied on MATLAB software gives a striking contrast between the real and fake Indian currency notes. The advantage of this technique is that the currency image can be captured by any type of simple scanner or digital camera in any lighting condition as well as can recognize the currency note from any direction and angle. From the output of the MATLAB programming the clear disparities obtained between genuine and counterfeit banknotes helps to detect a fake currency note very efficiently. The proposed approach for processing Indian currencies using IP seems to be a very simple and novel method and also open up entirely new application area for comparison of genuine and fake notes that have not previously been feasible or cost effective. 

Keywords: Indian currency notes, counterfeit, compare, MATLAB programming

JPMTR-2213 Case study | 167
DOI  10.14622/JPMTR-2213
UDC 336.74(540)004.93:343.5 

 Received: 2022-06-07
Accepted: 2022-07-15

Assessing and fostering media literacy education among undergraduate students: the competence in information retrieval and usability

Lalduhzuali, Amit Kumar, Dibanjyoti Buragohain and Manashjyoti Deka 

E-mails: maduhipachuau82@gmail.com; amit85kr@gmail.com; dibanrocks@gmail.com; manashdeka18@gmail.com 

Department of Library & Information Science, Mizoram University, Aizawl – 796004, India 

Abstract

The purpose of the present study is to provide the insight into media literacy awareness and practice among undergraduate students of Arts and Science disciplines at Pachhunga University College, Aizawl, followed by the emphasis on student’s skills of using the application of various media platforms for academic purposes. The random (purposive) sampling method has been used for collecting the required information. Many research studies have been conducted in the past with information literacy as the primary research topic. However, a review of the literature revealed that just a few studies have been conducted using media literacy as a primary focus. Consequently, this research contributes new knowledge to this less explored area of research. Paper concludes with suggestions to strengthen the awareness of media literacy among users. 

Keywords: information literacy, media literacy, electronic media, print media, digital media

JPMTR-2202 Case study | 168
DOI  10.14622/JPMTR-2202
UDC 371.8|37.014:004.773:005.336 

Received: 2022-03-08
Accepted: 2022-07-18