Application of box behnken design to optimize some parameters for flexographic printing process

Flexographic printing is a process that employs a flexible printing form and low viscous ink, often water-based. The flexible printing form is favourable for printing on rough surfaces, but the high surface tension of the ink may cause printability problems.This work has focused on the interaction between paper/paperboard coating and water-based flexographic ink, aimed at increasing the knowledge about the printing process in form of physical/chemical parameters that are important for ink setting. The effects of printing conditions on print quality, such as printing pressure and temperature, have also been in focus.The work has shown that fluids of different polarities, i.e. different dipole moments, behave differently when being absorbed by a coating layer. Due to their chemical compatibility to the coating layer, fluids with large dipole moment fill the pore matrix of the coating to a lesser extent but penetrate further into the coating than fluids with small dipole moments. On the other hand, polarity of the coating layer also affects the print. When printing on coatings with different polarities, higher print densities was obtained on the more polar substrates. As a tentative explanation, it is proposed that the ink builds different layer structures during drying depending on the coating polarity.Print gloss is related to the ink setting which, in turn, is affected by the solvent retaining capacity of the ink. Large water holding capacity allows the ink components to smoothen out before the structure is set, resulting in a higher print gloss. The rheology of inks is affected by temperature; at a higher temperature the viscosity is reduced. The reduction in ink viscosity at higher temperature has been shown to affect the print quality, e.g., print density and dot gain. It is suggested that a thicker layer is immobilised during impression due to the lower viscosity and that it is an explanation of the higher print density at a higher printing temperature.The influence of impression pressure on dot gain has been experimentally evaluated and mathematically modelled with good agreement. The dot gain is shown to respond non-linearly to the applied printing pressure.Studies based on pilot coated and printed paperboards is also reported, and it is shown that the print quality, e.g. print density, print gloss and dot gain, is largely dependent on the type of ink chosen and on the coating characteristics. Higher clay content in the coating resulted in increased dot gain and a decreased mottling.

Ink-jet printing is a non-contact printing, drops are jetted on the substrates to form images through the nozzles at a certain speed. Dot is the smallest unit in printing; the qualities of printing are seriously affected by dot gain. Ink spreading and penetration are discussed in this paper, influences on dot gain in ink-jet printing are studied, the original Young's equation and Washburn formula are theoretically amended, more scientific and rational models and formulas are obtained in the actual process of ink-jet printing, which offers reference standard and theoretical basis to improve the quality of ink-jet printing.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Amit Sharma, Vandana; Study of print contrast and dot gain on gloss coated paper printed by liquid toner and dry toner electrophotography process. AIP Conf. Proc. 27 February 2023; 2427 (1): 020090. https://doi.org/10.1063/5.0101502 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

ABSTRACTInks composed of renewable resources are important for the environment protection. We report preparation of a new type of edible chitosan‐based flexographic ink. The performance of three inks, containing three different molecular weight (MW) chitosan, was analyzed by the different experimental techniques. The Ink viscosity was investigated from the parameters shear rate, time, temperature, and flexographic printing simulation. The printing quality on coated paper was studied by the scratch resistance, contact angle, print fastness, chromatic aberration, and dot gain. Viscosity recovery rate reached 69% after 6 s, and the print fastness was up to 91%. The experimental ΔE is 0.97, the dot gain is 23%, and contact angle is 69° for the best ink. Experimental results indicate that the developed ink is suitable for the flexographic printing with good application prospects. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43997.

Increasing demand on micro-product leads to the development of innovative manufacturing process in nonconventional machining process to these micro-scale applications. In the medical field a huge variety of products can be found in prosthesis, surgery devices and tissue engineering, which required the application of the EDM process to manufacture micro cavities. Now-a-days the materials like Ti-alloy (Ti6Al4V) and 316L Stainless Steel are widely used in biomedical fields, which are very difficult to machine. These materials are also used in additive manufacturing process. Here it presents an experimental study of electro-discharge machining (EDM) of titanium alloy (Ti6Al4V) and 316L Stainless Steel. The objective of this work is to study the effect and optimization of machining process parameters like pulse-on-time, discharge current and duty cycle on process performance parameters such as material removal rate (MRR), tool wear rate (TWR) and Radial over cut (ROC). A Taguchi L9 design of experiment (DOE) has been applied and three levels of process parameters have been taken. The optimization method Grey relational analysis (GRA) method was used to optimize the parameters. The Analysis of Variance (ANOVA) also indicated the percentage contribution of machining parameters that influence response performance parameters. By the GRA method it was found that for Ti-alloy the machining parameter duty cycle (DC) has maximum percentage contribution on the output responses followed by discharge current (I p) and pulse on time (T ON). Similarly for 316L Stainless Steel the machining parameter discharge current (I p) has maximum percentage contribution on the output responses followed by pulse-on-time (T ON) and duty cycle (DC).

Dot gain is called Tone Value Increase (TVI). Low dot gain and rounder dot shape are important properties to obtain a good print. Dot gain is a measure of how much extra weight a given percent dot or tone has gained on the final printed substrate by comparison to the actual dot area on a press plate. Dot gain value depends on many factors. The interactions of paper, ink and press conditions are important determinates for a good print. In addition, the pigment coating process and calendering conditions have a significant effect on the printability of paperboards. Pigment coating formulations including mineral pigments, binders and additives improve the gloss, brightness, opacity and smoothness of the paperboards. As a result, print quality of paperboards increase. A uniform paperboard surface is needed to obtain a high quality surface smoothness after the coating process. High surface smoothness improves the uniformity of the dot shape and size. Pigment coating formulation parameters; pigment selection, binder selection and binder level influence print quality. The aims of this study - pigment selection and ratio - are to determine the effect on dot gain in lithography printing. To this aim, base paperboards were coated using five pigment coating formulations which included different combinations of kaolin, calcium carbonate and titanium dioxide pigment with a styrene\n-butyl acrylate copolymer binder using a bar application. After coating, the samples were air-dried overnight under TAPPI conditions. Then, half of the coated-paperboards were calendered. Tone scales from 1 to 100 % were offset printed using black ink on the uncalendered and calenderedcoated paperboards. Then, from the printed tone scale, the tone area values were measured with the Gretagmacbeth Spectrolino spectrophotometer. These values showed that pigment coating improved the surface optical and physical properties of paperboards. After calendering, the roughness values of coated paperboards decreased. In addition, the obtained dot and line sharpness on calendered-coated paperboards were better than on uncalenderedcoated paperboards. However, the dot gain values of calendered-coated paperboards had fewer dot gains than uncalendered-coated paperboards. It was established that the variation of pigment proportions in the coating formulations had no significant effect on dot gain.

Over the years, computing and information technology in the printing industry has been brought to a very high level. However, the models for assessing and estimating quality by considering print quality parameters are still being researched. This paper presents a mathematical model that was used for the purpose of enabling assessment of the flexographic print quality based on the visual experience of a standard observer. The model facilitates the assessment of print quality parameters’ impact on the visual experience of the high-quality flexographic print. As a part of this assessment process, print quality measurement analysis of each ink (cyan, magenta, yellow and black) was performed by focusing on several print quality parameters; dot gain at 50%, trapping, mottling, optical density and colour gamut. The use of logistic regression analysis in this paper allowed for a definition of nine variables that significantly impact the subjective perception of the total print quality. Methodology presented in this paper can be effectively applied in the scientific and professional practice of graphic design.

Flexographic printing is a common printing method in the packaging field. The printing method is characterized primarily by the flexible printing plate and the low viscosity inks which make it suitable for use on almost any substrate. The object of this study was to obtain further knowledge of the some important mechanisms of flexographic printing and how they influence the print quality. The thesis deals with printing primarily on board and liner but also on newsprint with water-borne ink using a full-scale flexographic central impression (CI) printing press. Several printing trials have been performed with a focus on the chemical interaction between the ink and substrate and the physical contact between the ink-covered printing plate and the substrate. Multicolour printing exposes the substrate to water from the water-containing ink. The emphasis was to investigate the relation between print quality and water-uptake of the paper surface with heat and water. Printing trials was carried out on substrates possessing a hydrophobic, and also a rather hydrophilic surface using a regular commercial water-borne ink. The favorable effect which water or surfactant solution had on the hydrophobic substrate with regard to print mottle could depend on its surface compressibility in combination with the hydrophobic nature of its surface that could affect the wetting properties. Conventional printing involves physical contact between plate and ink and between ink and substrate. A method for measuring the dynamic nip pressure using thin load cells is presented. Print quality was influenced by the plate material. A correction procedure taking into account the size of the sensor was developed in order to estimate the maximum dynamic pressure in the printing nip. An attempt was made to identify essential mechanical and chemical parameters, and also geometrical properties of the plate that affected print quality. Laboratory printing trials were carried out and a multivariate analysis was applied for evaluation of print quality data. The impact of the plate properties on print quality was evident. The essential properties of the plate that influence print quality were the small-scale roughness and long-scale roughness.

Abstract. Problem. For manufacturing enterprises, it is very important to reduce production and logistics costs, and one of the resource-intensive elements of this system is warehousing. Therefore, the need to establish conditions for the efficient use of material and warehouse resources is identified. Goal. The goal is to reduce the total cost of operating the built warehouse system by introducing efficient conditions for the use of resources. Methodology. A structural model of the warehouse system elements has been developed, which takes into account the main features of technological interaction of subsystems for processing incoming, internal and external flows of containers, packaging and finished products. To determine the conditions for efficient use of resources in the functioning of the warehouse system, it is proposed to use the evaluation parameter - the total cost of the warehouse system of a production enterprise. The parameters of external influence are the following intensities of flows determined by the warehouse process of a manufacturing enterprise: input, internal, and output. It is proposed to consider three options for the use of human and material resources. Originality. The article develops forecasting models of a degree type for three proposed three variants of use of material and human resources in functioning of warehouse systems of production enterprises. The obtained dependencies allow obtaining decisionmaking conditions depending on the intensity of incoming, internal and outgoing cargo flows. Practical value. Determining the conditions for using resources at the lowest possible total cost. The least costly option is to use two operators in each warehouse subsystem and one mechanism

Process optimization for the application of carbon from plantain peels in dye abstraction

The scattering of light within paper can affect the tone characteristics of a printed halftone image. A halftone image is formed by variation in the average reflectance, which is determined by the size of the ink dots. Photon migration within the paper from noninked to inked regions tends to increase the photon absorption and thus decrease the halftone reflectance—the dots are effectively larger than their physical size. This effect is known as optical dot gain or as the Yule-Nielson effect. The degree of optical dot gain depends on the distance that the photons migrate within the paper, which in turn depends on the paper's scattering and absorption characteristics, and on the thickness of the paper. We develop a theory that expresses the halftone reflectance in terms of the halftone microstructure—the screen period, dot size, dot shape, and ink transmission—and the effects due to the paper. The paper effects are represented in the theory by a point spread function, which is a conditional probability density that characterizes the photon migration within the paper, and by the paper's reflectance. We construct a model of photon transport within the paper by solving the transport equation using a diffusion approximation, from which we derive a point spread function. We interpret the expanded Murray–Davies model of halftone reflectance in terms of the theory developed here by giving a probabilistic interpretation to optical dot gain. We show that optical dot gain can be related to a single numerical parameter. Using the diffusion point spread function, we show how this parameter is related to the physical quantities that characterize the paper.

In contemporary printing processes, dot gain is a pivotal factor influencing print quality. This phenomenon, characterized by the loss of image details and the potential for chromatic aberration, poses significant challenges to enhancing print quality. Despite extensive research that has been conducted by numerous scholars on dot gain, effective control and correction of this phenomenon in practical printing operations remain an urgent concern. This study utilized newsprint, offset paper, and coated paper as research objects, and employed the least squares method and MATLAB tools to calculate dot gain compensation values through the “coordinate transformation method” and fit the compensation curve of dot gain. The novelty of this research lies in its development of an integrated mathematical modeling approach that combines least squares optimization with coordinate transformation, providing a computationally efficient alternative to traditional inverse function methods. The experimental results demonstrated that the compensation strategy was effective in the mid-tone and dark-tone areas, significantly enhancing printing accuracy and stability. However, in the bright tone area, further optimization of the compensation effect is necessary. The study proposes a dot gain compensation strategy based on the least squares method, providing the printing industry with new ideas and technical support for enhancing printing quality.

Photopolymer plates are expected to produce good area coverage with low dot gain, fine reverses and light halftones. However, the obtained print results often differ depending on plate system used such as type of photopolymer plate, cushion materials and double-sided tape. Thus, the choice of the particular elements used have an impact on the plate system performance, which relevant to dot gain and ink transfer. To determine the performance of the plate system in detail, we need to know plate properties such as surface hardness, elasticity, surface energy including its caliper, the pressure absorbency characteristics of the cushion and the press setting. Thus, a number of checking procedures are introduced to define the effects of the plate system's performance on printing quality. This includes checking material specifications, and the condition of press such as register, anilox roller, doctor blade system and press setting. Experimental design for adhesive label UV flexographic printing thus was proposed and printed jobs had been evaluated. The amount of ink transfer has been measured and the ink transfer model has been established. Then the ink transfer has been analyzing and compare to printed quality of print targets and stepwedges. The results showed that the total amount of ink transfer affected tone gradation, print uniformity, fine reverse and dot gain. While better ink transfer from plate to substrate could affect towards darker edge of fonts of the reverse print, good print uniformity and less gradation. Note that the total dotgain results showed complexity as there were other factors involved such as surface energy, compressibility and surface hardness of printing plate too.

From Rio to Iragua--sustainability versus efficiency and equity for preventive health interventions.

Printing has revolutionized not only the religious and educational world by providing printing on paper but also the commercial world by providing end-to-end solutions for packaging by printing on materials like plastics. Print quality refers to level of details and sharpness of printed products for wider acceptability. Print quality has an important role in maintaining consistency during printing on selected surfaces to provide desired satisfaction. Printability and runnability of substrates, substrate surface characteristics, and printing ink properties are attributes of print quality and are considered important for determining good quality printing. Solid ink density (SID), Hue error, grayness and ink trapping are some of the important measurable printability factors that play an important role in determining the print quality irrespective of substrates. Gravure printing and flexography printing are high-speed printing suitable for printing on flexible substrates so, attempts were made for explore the mutual compatibilities of new-generation printing substrates with established printing processes, which will prove to be a boon in the future by replacing conventional plastics with bio-based biodegradable plastics in printing for packaging and its other applications. So, multi-color printing on selected bio-based biodegradable plastics were explored for determining printability by measuring and maintaining print quality attributes during print runs.