Printing Quality Control Research Articles

Color detection of printing based on improved superpixel segmentation algorithm

We propose an improved superpixel segmentation algorithm based on visual saliency and color entropy for online color detection in printed products. This method addresses the issues of low accuracy and slow speed in detecting color deviations in print quality control. The improved superpixel segmentation algorithm consists of three main steps: Firstly, simulating human visual perception to obtain visually salient regions of the image, thereby achieving region-based superpixel segmentation. Secondly, adaptively determining the superpixel size within the salient regions using color information entropy. Finally, the superpixel segmentation method is optimized using hue angle distance based on chromaticity, ultimately achieving a region-based adaptive superpixel segmentation algorithm. Color detection of printed products compares the color mean values of post-printing images under the same superpixel labels, outputting labels with color deviations to identify areas of color differences. The experimental results show that the improved superpixel algorithm introduces color phase distance with better segmentation accuracy, and combines it with human visual perception to better reproduce the color information of printed materials. Using the method described in this article for printing color quality inspection can reduce data computation, quickly detect and mark color difference areas, and provide the degree of color deviation.

Quality control of 3D printing in bioarchaeology: a case study on dimensional assessment of cranial models

In the last few years, 3D printing has gained widespread use in archaeology and cultural heritage fields, from research and conservation to enriching museum experiences. This study focuses on Fused Deposition Modeling (FDM) technology to assess the quality of printed replicas of archaeological human remains. A cranial model was 3D printed (3DP) from Computed Tomography (CT) data of an 8-year-old patient to simulate the remains of an archaeological skull. Eight copies were then printed and subjected to CT scanning to compare them to the original model through an objective measurement method based on image analysis. The proposed method investigates print variability and considers potential sources of error to assess the dimensional compatibility of the model before and after printing. Results showed an increasing error, up to 15 %, with higher levels of model detail. These results are discussed with reference to a metrological approach, highlighting the need for further research into optimizing 3D printing quality control, including through the definition of a standardized protocol to obtain archaeological replicas faithful to the originals.

Non-contact microwave sensor for FDM 3D printing quality control

ABSTRACT In recent years, 3D printing has undergone a transformational journey – from prototyping technology, limited to laboratories, to a production method used in industry – becoming a powerful tool for creating functional objects. Despite this progress, 3D printing faces ongoing challenges related to defect detection and print quality control. We present an innovative, non-contact, fast and cheap microwave sensor for detecting defects in printed components, related to both mechanical errors and conductivity inhomogeneities. We discuss in detail the methodology of the microwave surface mapping technique and the results obtained for several samples printed with popular filaments. Tests show the ability to detect faults with millimetre precision. The simple design of the entire quality control module allows for easy integration with various types of 3D printers, from popular ones used by hobbyists to professional, highly specialised ones.

Investigation on geometric and surface finish quality of 3D concrete printed walls with hollow section

3D concrete printed walls with hollow sections are now widely adopted in 3D concrete printing applications across the construction industry. One of the significant challenges in the printing process is achieving superior surface finishes. Previous research has predominantly focused on the overall geometry of these walls, often neglecting surface finish quality at the intersections of formwork and supporting filaments. This study is dedicated to optimizing the geometric arrangement of supporting filaments and enhancing print quality at these critical intersections. Firstly, two arrangement strategies, the standard approach and the average approach, are introduced to establish high-quality geometric section configurations, with practical demonstrations on both rectangular and arc-shaped walls. Subsequently, the width of concrete filaments is considered to enhance surface finish quality at the intersections. Two print quality control methods, namely the e- Δ control rule and the r- Δ control rule, are then developed. To assess the effectiveness of these arrangement strategies and control methods, configurations of walls with specific dimensions are compared, and printing experiments are conducted. Finally, recommendations for practical application are provided, aimed at improving both the geometric and surface finish quality of 3D concrete printed walls with hollow sections.

Architectural 3D-Printed Structures Created Using Artificial Intelligence: A Review of Techniques and Applications

Artificial Intelligence (AI) and 3D printing (3DP) play considerable roles in what is known as the Fourth Industrial Revolution, by developing data- and machine-intelligence-based integrated production technologies. In architecture, this shift was induced by increasingly complex design requirements, posing important challenges for real-world design implementation, large-scale structure fabrication, and production quality standardization. The study systematically reviews the application of AI techniques in all stages of creating 3D-printed architectural structures and provides a comprehensive image of the development in the field. The research goals are to (1) offer a comprehensive critical analysis of the body of literature; (2) identify and categorize approaches to integrating AI in the production of 3D-printed structures; (3) identify and discuss challenges and opportunities of AI integration in architectural production of 3D-printed structures; and (4) identify research gaps and provide recommendations for future research. The findings indicate that AI is an emerging addition to the 3DP process, mainly transforming it through the real-time adjustment of the design or printing parameters, enhanced printing quality control, or prediction and optimization of key design features. However, the potential of the application of AI in large-scale architectural 3D printing still needs to be explored. Lastly, the study emphasizes the necessity of redefining traditional field boundaries, opening new opportunities for intelligent architectural production.

Printing quality control of cement-based materials under flow and rest conditions

Time-dependent rheological properties of cement-based materials have a significant impact on 3D printing processes, where multiple rheological requirements should be met. A proper high rate of structural build-up is recommended to ensure the buildability and stability of printed elements. However, the loss of workability may occur rapidly, resulting in a significant reduction in print quality. Workability and buildability requirements usually interfere due to the time-dependent rheological behavior of cement-based materials under flow and rest conditions. This research aims to highlight the effects of time-dependent behavior on the printability of cement-based materials. The coupling mechanisms of microstructure development at rest and under shearing conditions are discussed. A new thixotropy index is proposed to quantify the printability window of cement-based materials based on their structuration rates. An experimental study was conducted on printable mortars incorporating a viscosity-modifying agent (VMA) to assess printing quality as a function of the degree of thixotropy. Different types of stability failures were captured and discussed.

Image Analysis Based Evaluation of Print Quality for Inkjet Printed Structures

Inkjet printing for printed electronics is a growing market due to its advantages, including scalability, various usable materials and its digital, pixel based layout design. An important quality factor is the wetting of the ink on the substrate. This article proposes a workflow to evaluate the print quality of specific layouts by means of image analysis. A self-developed image analysis software, which compares a mask with the actual layout, enables a pixel-based analysis of the wetting behavior by the implementation of two parameters called over- and underwetting rate. A comparison of actual and targeted track widths can be performed for the evaluation of different parameters, such as the tested plasma treatment, drop spacing (DS) and substrate temperature. To prove the functionality of the image analyses tool, the print quality of Au structures inkjet printed on cyclic olefin copolymer (COC) substrates was studied experimentally by varying the three previously mentioned parameters. The experimental results showed that the wetting behavior of Au ink deposited on COC substrates influences various line widths differently, leading to higher spreading for smaller line widths. The proposed workflow is suitable for identifying and evaluating multiple tested parameter variations and might be easily adopted for printers for in-process print quality control in industrial manufacturing.

Analysis of Cup Printing Quality Control Using Statistical Process Control Methods and Human Reliability Assessment (Case Study: PT Indo Ceria Plastic Printing)

This research was conducted at PT Indo Ceria Plastic Printing aims to determine the main cause of defective cup printing and to reduce product defects in the production process. Based on the problems faced by the company, namely the high percentage of cup printing defects which eventually led to more and more reject cup printing rates, even the problem of passing the defective cup being sent to the customer’s hands, which made the customer complain about the problem of the number of bad product quality being sent so that they finally submitted a returned product. Therefore, quality control efforts are carried out on cup printing products to find the cause of the defect and find a solution to repair it. The research methods used in solving the problems that occur at PT Indo Ceria Plastic Printing is to use Statistical Process Control methods and Human Reliability Assessment. From the result of research conducted, it is known that the biggest cause of defect in cup printing products is “defect awal start”. From the results of meaning employee performance, the largest HEP value was found, namely, the type of possible error is “pengisian tinta pada mesin” which was 0,6324. So, this factor was the dominant one that resulted in defects and must be repaired immediately.

A quantitative analysis of overspray in Aerosol Jet® printing

As Aerosol Jet® (AJ) printing is becoming more attractive to additive manufacturing, printed electronics, among other applications, reducing or minimizing the amount of ink droplets landing in unintended regions—known as the overspray—has been elevated on the agenda for print quality control and improvement. Many AJ users had discussed the overspray issue associated with AJ printing, while the metrology for quantified evaluation of overspray is still lacking. In this work, the likely physical mechanism for inducing overspray is analyzed along with a set of computational fluid dynamics (CFD) simulations. We then present a 2D image processing method for quantitatively evaluating the severity of overspray in terms of its percent area coverage versus a normalized distance from printed line edge. Our results show that the amount of overspray of AJ printing seems to scale with the printed line width (LW), and usually to become negligible (e.g. percent area coverage of overspray < 1%) beyond 30%–40% of LW from line edges. The overspray is shown to often decrease by increasing the jet velocity and sheath-to-mist ratio. Without loss of generality and for concise illustration, herewith we use only one representative ink to print test samples for the quantitative overspray analysis. The results have been found to bear a resemblance to AJ printed features with many other inks.

Effects of exposure time and printing angle on the curing characteristics and flexural strength of ceramic samples fabricated via digital light processing

The development of photosensitive slurries for additive manufacturing has attracted great interest due to their correlation with the final properties of the fabricated parts. This paper focus on the printing quality control in digital light processing (DLP) 3D printing of advanced ceramics. Systematic experiments were performed to assess the effects of the exposure time and printing angle on the three-point bending strength of the fabricated samples. The exposure time affected the bending strength of the printed zirconia ceramic dramatically. When the weak exposure time is 1 s and the strong exposure time is 13 s, the average bending strength can reach 580 MPa while Weibull modulus can reach 8.84. Meanwhile, the printing angle also affected the bending strength mechanical sample printed at 45° exhibits the worst performance.

Industrial Optical Character Recognition System in Printing Quality Control of Hot-Rolled Coils Identification

This work presents a system designed to detect printing errors and misidentifications on steel coils that could lead to tracking problems and even guide to the delivery of the wrong product to the final client. An optical character recognition system is proposed to extract the printed identification of steel coils from images captured by a fixed camera in an industrial environment. The method considers different digital image processing techniques to deal with the significant lighting and printing variation observed, followed by a segmentation process that extracts and aligns the characters originally printed in an arch form, ending with a classification routine based on a convolutional neural network. The proposed system presents an approach to treat lighting variations in images, covering low contrast, darker and brighter images. Experiment carried out on a data set with approximately 20,000 images achieved an accuracy higher than 98%, supporting the validity of the proposed method.

Development of Professional Competency for Printing Quality Control Personnel Using Training System via Edmodo

Abstract This study aimed to solving problems in providing printing quality control personnel to Thai printing industry. The problems which are mainly concerned including: (1) the lack of competency and ability in authentic performance as well as (2) the lack of capacity in following the professional standard. Therefore, the study employs Edmodo to facilitate the training system. The research procedures included these following processes: (1) reviewing literature, (2) Exploring and evaluating the needs, (3) developing the training system prototype, (4) Evaluating the conceptual framework developed, (5) Drafting the training package through Edmodo, (6) evaluating and Implementing the training system, and (7) Taking the result into improving. The result elucidated that the developed PQC-Training system, after being applied into creating the training package by using the Edmodo website and application, could effectively promote the trainees’ professional competency that was in accordance to requirements of organizations in Thai printing industry.

Printing quality control automation

One of the most important problems in the concept of standardizing the process of offset printing is the control the quality rating of printing and its automation. To solve the problem, a software has been developed taking into account the specifics of printing system components and the behavior in printing process. In order to characterize the distribution of ink layer on the printed substrate the so-called deviation of the ink layer thickness on the sheet from nominal surface is suggested. The geometric data construction the surface projections of the color gamut bodies allows to visualize the color reproduction gamut of printing systems in brightness ranges and specific color sectors, that provides a qualitative comparison of the system by the reproduction of individual colors in a varying ranges of brightness.

The Papers Printing Quality Complex Assessment Algorithm Development Taking into Account the Composition and Production Technological Features

Paper is one of the printing system key components causing the high-quality printed products output. Providing the printing companies with the specified printing properties paper, while simultaneously increasing the paper products range and volume by means of the forecasting methods application and evaluation during the production process, is certainly a relevant problem. The paper presents the printing quality control algorithm taking into consideration the paper printing properties quality assessment depending on the manufacture technological features and composition variation. The information system including raw material and paper properties data and making possible pulp and paper enterprises to select paper composition optimal formulation is proposed taking into account the printing process procedure peculiarities of the paper manufacturing with specified printing properties.

Effect of Electrode Distance on Jetting Behavior of Non-Particle Nano Ag Conductive Ink in Electrohydrodynamic Micro Jet Printing

The effect of electrode distance on jetting behavior of non-particle nanoAg conductive ink during Electrohydrodynamics (EHD) under the direct current voltage is investigated. Experiments results indicate that the height of the meniscus increases while the curve decreases with the increase of electrode distance, and the jetting behavior evolves from pulsate cone jetting to pulsate micro dripping jetting. The low voltage combined with long electrode distance resulted in returning of meniscus to its original shape. With the increase of voltage, the increased electrode distance result in the increase of meniscus deformation and the electrode distance for maintaining the stable jetting was increased. Under the same voltage, the line width increases with the increase of electrode distance. The exceeded long electrode distance and high voltage resulted in jitter of elongated meniscus thus is not beneficial for the printing quality control.

Print Quality Control Management for Papers Containing Optical Brightening Agents

Optical brightening agents (OBAs) or fluorescent whitening agents (FWAs) are chemicals added to paper during the papermaking process to increase the brightness of paper (chemical additives that increase the reflection of blue light (caused by ultraviolet light with a wavelength below 400nm) for the correction of a natural yellow color of paper pulp). Papers with agents for optical brightening are often represented on the market. The aim of this paper is to show that colors reproduced on paper with (Iggesund Incada Silk, 220g/m) and without (Iggesund Incada Silk T, 205g/m) agents for optical brightening, are different during the same printing conditions. Standard ISO 13655 (Spectral Measurement and Colorimetric Computation for Graphic Arts Images) defines the “M” series of illumination, which provides color management in these conditions.

The impact of applying instructional design principles on students’ attitudes towards the learning content

Abstract The aim of this empirical study is to measure the impact of applying instructional design principles on students’ attitudes towards learning content. A course entitled ‘Print Quality Control’ offered in the study plan of the Department of Printing, Publishing and Packaging at the Faculty of Applied Arts, Helwan University in Egypt, was selected for the conduct of this experimental work. The course was taught to Group (A) in spring 2008 academic semester. Students’ attitudes towards the following four variables were measured: ‘clarity of course objectives’, ‘appropriateness of the content to the objectives’, ‘information presentation’ and ’ease of understanding the content’. The results of the study in this phase revealed shortcomings in the four variables, as 68 per cent of the students appreciated the clarity of course objectives, 73.5 per cent the appropriateness of the content to the objectives, 70.5 per cent the information presentation and finally 61.5 per cent the ease of understanding the content. Based on the earlier findings, the course was then updated and two importantn analyses were conducted: the first was analysis of the course learning outcomes, and the second was analysis of the updated content. Thereafter and to fill in the gaps found in the original course, a new course design was developed using media and e-learning development tools, including Adobe Photoshop, Adobe Premiere, Adobe Director, Adobe Flash and Course Genie. This course design was achieved through the application of instructional design principles within a frame of learning theories and the systematic development of the learning materials. The new course design was then validated by ten experts using the BACMAN model and got an average of 4.1 out of 5; it was subsequently published through the Blackboard Learning Management System and taught to Group (B) in spring 2009 academic semester. An analysis of students’ attitudes in Group (B) revealed noticeable improvements in relation to the same variables; 100 per cent of the students appreciated the clarity of course objectives, 100 per cent the appropriateness of the content to the objectives, 83.3 per cent the information presentation and finally 100 per cent the ease of understanding the content.

Exploration of Factors to Influence Solid Density Based on the Xerographic Toner Digital Printing Field

With the rapid development of the printing industry, relying on its flexibility and advantage for short-run printing, the use of digital printing in various areas of the market becomes more widely. Digital print quality evaluation and control is particularly important. Among them, the solid density is an important indicator of print quality evaluation. Using different digital printing methods, the factors to influence the density is different. In this paper, two factors that affect xerographic toner solid density were discussed base on the principle of electrostatic imaging and toner transfer and fusing process. Experiments analyzed different transfer supply voltage conditions on CMYK four-color solid density; and the fusing temperature on CMYK four-color solid density. The results showed that: transfer supply voltage and fusing temperature are influential factors on the four-color solid density.

Modeling ink diffusion within paper to achieve a raggedness ruler for print quality control

Raggedness is one of the most important print quality factors. It is defined as the appearance of geometric distortion of an edge from its ideal position that should be absolutely straight along the length of the line. Raggedness is caused by several phenomena. The non-uniformity absorption of ink, which may be because of the paper roughness or ink quality, may cause various degree of raggedness. Print quality assessments are usually based on comparing a test sample with a reference as a ruler of different quality samples. Therefore, it is important to prepare appropriate rulers for different quality metrics. The present study introduces a new method for modeling of raggedness by simulating ink diffusion within paper. It is assumed that different parts of a paper have different diffusion coefficients, so the ink can randomly diffuse through different paths. These paths can be changed via paper properties and drying time. Using this method and controlling the effective variables it is expected to generate different levels of raggedness. The experimental results show that with the proposed method it is possible to achieve different levels of raggedness, which can be used to generate test targets and raggedness rulers. Also, it can standardize objective and subjective test methods for measuring raggedness.

Компактный микрочип для типирования вируса гриппа А

A universal oligonucleotide hybridazation microchip 6 x 5 spot (4 x 4 mm) for influenza A virus subtyping was suggested, functioning on a principle one spot--one subtype. This microchip with additional printing quality control is a prototype of a biosensor for detection of influenza A virus and typing of 15 subtypes of hemagglutinin and 9 subtypes of neuraminidase.