Sports betting has become more prevalent, visible and socially accepted in Western liberal societies than ever before. This normalisation of gambling on sports has been fuelled by…
Abstract
Sports betting has become more prevalent, visible and socially accepted in Western liberal societies than ever before. This normalisation of gambling on sports has been fuelled by deregulation, the omnipresence of advertising and the growing dependency of elite sports on sponsorship revenue streams from the gambling industry. That said, much remains to be uncovered about the mechanisms through which this normalisation of gambling occurs in sports. This chapter focuses on the role of sports clubs in Belgium and the Netherlands, drawing on empirical insights from two related studies that examine the oft-neglected salience of integrity as a key factor shaping gambling-related policy and practice at the organisational level. This sets the stage for a critical research agenda that can support the denormalisation of gambling, and the deconstruction of dominant discourses that frame sports betting as a fun, risk-free social practice.
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K.H. Low, K.F. Leong, C.K. Chua, Z.H. Du and C.M. Cheah
There are many applications for rapid prototyping systems and application in the biomedical field is an important domain. Uses selective laser sintering (SLS) in this study to…
Abstract
There are many applications for rapid prototyping systems and application in the biomedical field is an important domain. Uses selective laser sintering (SLS) in this study to build porous cylindrical disc matrices for use as drug delivery devices (DDD). Studies the part‐bed temperature to ascertain its influence over the porosity of the disc matrices. They are found to have an inverse linear relationship. Also investigates the dense walls, the inherent consequences of building porous structures with the SLS, in the disc matrix as they have a direct impact on the performance of the DDD. Discusses the size constraint of the disc matrix due to the limitations of the SLS process. Also investigates the possibility of creating disc matrices of varying porosity. Experimental results demonstrate that SLS is viable in producing DDDs that have variable porosity and micro‐features.
S.‐J.J. Lee, E. Sachs and M. Cima
Emerging technologies commonly known as “rapid prototyping” fabricate solid objects directly from computer models by building parts in thin layers. Three‐dimensional printing is…
Abstract
Emerging technologies commonly known as “rapid prototyping” fabricate solid objects directly from computer models by building parts in thin layers. Three‐dimensional printing is one such process that creates engineering prototypes and tooling by joining powder particles selectively on a layer‐by‐layer basis. The powder‐based approach offers tremendous flexibility in geometry and materials, but it makes layer position accuracy a fundamental concern for dimensional control in the vertical direction. Ideally, each powder layer is generated at a vertical position that remains fixed, at a prescribed distance with respect to a machine reference. However, compressive loads imparted to a stack of layers (by the weight of subsequent layers, for example) may cause the layers to displace downward. Develops a model for layer displacement using experimental data for compressibility and applied load. Compares predictions made from the model to measured displacements, and the predictions successfully captured the relative magnitudes of actual errors at various positions within layered powder beds. Position changes were most severe in the middle regions of the powder beds, with diminishing magnitude towards the top and bottom. Uses aluminium oxide powder in two different sizes (approximately of 10‐micron and 30‐micron diameter) and two different shapes (platelet and spherical) in the studies. The average measured displacement in a 76.2mm deep bed ranged from 23 microns for a 30‐micron platelet‐shaped powder to over 260 microns for a 9‐micron platelet‐shaped sample.
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Grant Marchelli, Renuka Prabhakar, Duane Storti and Mark Ganter
This purpose of this paper is to provide an overview of the steps and processes behind successfully adapting novel materials, namely virgin glass and recycled glass, to…
Abstract
Purpose
This purpose of this paper is to provide an overview of the steps and processes behind successfully adapting novel materials, namely virgin glass and recycled glass, to three‐dimensional printing (3DP).
Design/methodology/approach
The transition from 3DP ceramic systems to glass systems will be examined in detail, including the necessary modifications to binder systems and printing parameters. The authors present preliminary engineering data on shrinkage, porosity, and density as functions of peak firing temperature, and provide a brief introduction to the complexities faced in realizing an adequate and repeatable firing method for 3D printed glass.
Findings
Shrinkage behavior for the 3D printed recycled glass showed significant anisotropy, especially beyond peak firing temperatures of 730°C. The average shrinkage ratios for the slow‐ and fast‐axes to the Z‐axis were 1:1.37 and 1:2.74, respectively. These extreme differences can be attributed to the layer‐by‐layer production method and binder burn‐off. At 760°C, the apparent porosity reached a minimum of 0.36 percent, indicative of asymptotic behavior that approaches a fully dense 3DP glass specimen. At low firing temperatures, the bulk density was similar to water, but increased to a maximum of 2.41 g/cm3. This indicates that 3DP recycled glass can behave similarly to common glass with accepted published bulk densities ranging from 2.4‐2.8 g/cm3.
Research limitations/implications
Heating schedule analysis and optimization may reduce geometric variations, therefore, the firing method should be investigated in greater depth.
Originality/value
This paper provides a guide to successfully adopting glass to commercially available 3DP hardware. This research has also enabled rapid prototyping of recycled glass, a monumental step towards a sustainable future for 3DP.
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Yun Bai and Christopher B Williams
The purpose of this paper is to explore the use of binder jetting to fabricate high-purity copper parts. The ability to fabricate geometrically complex copper shapes would have…
Abstract
Purpose
The purpose of this paper is to explore the use of binder jetting to fabricate high-purity copper parts. The ability to fabricate geometrically complex copper shapes would have implications on the design and manufacture of components for thermal management systems and structural electronics.
Design/methodology/approach
To explore the feasibility of processing copper via binder jetting, the authors followed an established material development process that encompasses powder selection and tuning process parameters in printing and thermal cycles. Specifically, the authors varied powder size and sintering cycles to explore their effects on densification.
Findings
Three differently sized copper powders were successfully printed, followed by sintering in a reducing atmosphere. It was found that a 15-μm-diameter powder with a sintering cycle featuring a 1,080°C maximum temperature provides the most dense (85 per cent) and pure (97 per cent) final copper parts of the parameters tested.
Research limitations/implications
Due to powder-based additive manufacturing techniques’ inherent limitations in powder packing and particle size diameter, there are difficulties in creating fully dense copper parts. To improve thermal, electrical and mechanical properties, future work will focus on improving densification.
Originality/value
The paper demonstrates the first use of binder jetting to fabricate copper artifacts. The resulting copper parts are denser than what is typically found in binder jetting of metal powders (without infiltration); significant opportunity remains to further optimize the manufacturing process by introducing novel techniques to tailor the material properties for thermal/electrical applications.
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Ramakrishna Vasireddi and Bikramjit Basu
The purpose of this paper is to investigate the possibility to construct tissue-engineered bone repair scaffolds with pore size distributions using rapid prototyping techniques…
Abstract
Purpose
The purpose of this paper is to investigate the possibility to construct tissue-engineered bone repair scaffolds with pore size distributions using rapid prototyping techniques.
Design/methodology/approach
The fabrication of porous scaffolds with complex porous architectures represents a major challenge in tissue engineering and the design aspects to mimic complex pore shape as well as spatial distribution of pore sizes of natural hard tissue remain unexplored. In this context, this work aims to evaluate the three-dimensional printing process to study its potential for scaffold fabrication as well as some innovative design of homogeneously porous or gradient porous scaffolds is described and such design has wider implication in the field of bone tissue engineering.
Findings
The present work discusses biomedically relevant various design strategies with spatial/radial gradient in pore sizes as well as with different pore sizes and with different pore geometries.
Originality/value
One of the important implications of the proposed novel design scheme would be the development of porous bioactive/biodegradable composites with gradient pore size, porosity, composition and with spatially distributed biochemical stimuli so that stem cells loaded into scaffolds would develop into complex tissues such as those at the bone–cartilage interface.
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Nataraj Poomathi, Sunpreet Singh, Chander Prakash, Arjun Subramanian, Rahul Sahay, Amutha Cinappan and Seeram Ramakrishna
In the past decade, three-dimensional (3D) printing has gained attention in areas such as medicine, engineering, manufacturing art and most recently in education. In biomedical…
Abstract
Purpose
In the past decade, three-dimensional (3D) printing has gained attention in areas such as medicine, engineering, manufacturing art and most recently in education. In biomedical, the development of a wide range of biomaterials has catalysed the considerable role of 3D printing (3DP), where it functions as synthetic frameworks in the form of scaffolds, constructs or matrices. The purpose of this paper is to present the state-of-the-art literature coverage of 3DP applications in tissue engineering (such as customized scaffoldings and organs, and regenerative medicine).
Design/methodology/approach
This review focusses on various 3DP techniques and biomaterials for tissue engineering (TE) applications. The literature reviewed in the manuscript has been collected from various journal search engines including Google Scholar, Research Gate, Academia, PubMed, Scopus, EMBASE, Cochrane Library and Web of Science. The keywords that have been selected for the searches were 3 D printing, tissue engineering, scaffoldings, organs, regenerative medicine, biomaterials, standards, applications and future directions. Further, the sub-classifications of the keyword, wherever possible, have been used as sectioned/sub-sectioned in the manuscript.
Findings
3DP techniques have many applications in biomedical and TE (B-TE), as covered in the literature. Customized structures for B-TE applications are easy and cost-effective to manufacture through 3DP, whereas on many occasions, conventional technologies generally become incompatible. For this, this new class of manufacturing must be explored to further capabilities for many potential applications.
Originality/value
This review paper presents a comprehensive study of the various types of 3DP technologies in the light of their possible B-TE application as well as provides a future roadmap.
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Weiwei Wu, Zhouzhou Wang, Shuang Ding, Aiping Song and Dejia Zhu
The effects of infiltrant-related factors during post-processing on mechanical performance are fully considered for three-dimensional printing (3DP) technology. The factors…
Abstract
Purpose
The effects of infiltrant-related factors during post-processing on mechanical performance are fully considered for three-dimensional printing (3DP) technology. The factors contain infiltrant type, infiltrating means, infiltrating frequency and time interval of infiltrating.
Design/methodology/approach
A series of printing experiments are conducted and the parts are processed with different conditions by considering the above mentioned four parameters. Then the mechanical performances of the parts are tested from both macroscopic and microscopic papers. In the macroscopic view, the compressive strength of each printed part is measured by the materials testing machine – Instron 3367. In the microscopic view, scanning electron microscope and energy dispersion spectrum are used to obtain microstructure images and element content results. The pore size distributions of the parts are measured further to illustrate that if the particles are bound tightly by infiltrant. Then, partial least square (PLS) is used to conduct the analysis of the influencing factors, which can solve the small-sample problem well. The regression analysis and the influencing degree of each factor are explored further.
Findings
The experimental results show that commercial infiltrant has an outstanding performance than other super glues. The infiltrating action will own higher compressive strength than the brushing action. The higher infiltrating frequency and inconsistent infiltrating time interval will contribute to better mechanical performance. The PLS analysis shows that the most important factor is the infiltrating method. When compare the fitted value with the actual value, it is clear that when the compressive strength is higher, the fitting error will be smaller.
Practical implications
The research will have extensive applicability and practical significance for powder-based additive manufacturing.
Originality/value
The impact of the infiltrating-related post-processing on the performance of 3DP technology is easy to be ignored, which is fully taken into consideration in this paper. Both macroscopic and microscopic methods are conducted to explore, which can better explain the mechanical performance of the parts. Furthermore, as a small-sample method, PLS is used for influencing factors analysis. The variable importance in the projection index can explain the influencing degree of each parameter.
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Mukesh K. Agarwala, Vikram R. Jamalabad, Noshir A. Langrana, Ahmad Safari, Philip J. Whalen and Stephen C. Danforth
Commercial solid freeform fabrication (SFF) systems, which have been developed for fabrication of wax and polymer parts for form and fit and secondary applications, such as moulds…
Abstract
Commercial solid freeform fabrication (SFF) systems, which have been developed for fabrication of wax and polymer parts for form and fit and secondary applications, such as moulds for casting, etc., require further improvements for use in direct processing of structural ceramic and metal parts. Defects, both surface as well as internal, are undesirable in SFF processed ceramic and metal parts for structural and functional applications. Process improvements are needed before any SFF technique can successfully be commercialized for structural ceramic and metal processing. Describes process improvements made in new SFF techniques, called fused deposition of ceramics (FDC) and metals (FDMet), for fabrication of structural and functional ceramic and metal parts. They are based on an existing SFF technique, fused deposition modelling (FDM) and use commercial FDM systems. The current state of SFF technology and commercial FDM systems results in parts with several surface and internal defects which, if not eliminated, severely limit the structural properties of ceramic and metal parts thus produced. Describes systematically, in detail, the nature of these defects and their origins. Discusses several novel strategies for elimination of most of these defects. Shows how some of these strategies have successfully been implemented to result in ceramic parts with structural properties comparable to those obtained in conventionally processed ceramics.
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Hadi Miyanaji, Niknam Momenzadeh and Li Yang
This study aims to experimentally investigate the effect of the powder material characteristics on the qualities of the binder jetting additive manufacturing parts both before and…
Abstract
Purpose
This study aims to experimentally investigate the effect of the powder material characteristics on the qualities of the binder jetting additive manufacturing parts both before and after post processing (sintering).
Design methodology/approach
Three different types of the 316L stainless steel powder feedstock with various mean particle sizes and size distributions were studied. The influence of the powder particle size distributions and pore sizes on the powder bed packing densities and on the dynamics of the binder droplet-powder bed interactions were characterized. In addition, the surface roughness and densities of these parts both in the green state and after sintering were studied.
Findings
The results revealed the significant role of the powder feedstock characteristics on the liquid binder/powder bed interaction and consequently on the dimensional accuracies of the green parts. It was observed that the parts printed with the smaller mean particle sizes resulted in better surface finish and higher final densities after sintering. Furthermore, the hardness of the sintered parts produced with smaller powder particles exhibited higher values compared to the parts fabricated with the larger particles. On the other hand, larger particle sizes are advantageous for various green part qualities including the dimensional accuracies, green part densities and surface roughness.
Originality/value
This study establishes more comprehensive correlations between the powder feedstock characteristics and various quality criteria of the printed binder jetting components in both green and sintered states. These correlation are of critical importance in choosing the optimal process parameters for a given material system.