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Article
Publication date: 20 June 2016

Thomas Niendorf, Florian Brenne, Mirko Schaper, Andre Riemer, Stefan Leuders, Wilfried Reimche, Dieter Schwarze and Hans J. Maier

As additive manufacturing techniques, such as selective laser melting, allow for straightforward production of parts on basis of simple computer-aided design files only…

541

Abstract

Purpose

As additive manufacturing techniques, such as selective laser melting, allow for straightforward production of parts on basis of simple computer-aided design files only, unauthorized replication can be facilitated. Thus, identification and tracking of individual parts are increasingly vital in light of globalized competition. This paper aims to overcome the susceptibility of additive manufacturing techniques for product piracy by establishing a method for introducing and reading out product identification markers not visible by naked-eye inspection.

Design/methodology/approach

Lasers of different nominal power were used for altering the solidification mechanisms during processing in distinct areas of the samples. The resulting local microstructural characteristics and mechanical properties, respectively, were determined by scanning electron microscopy and hardness measurements. The applicability of an advanced eddy current technique for reading out local differences in electro-magnetic properties was examined.

Findings

The findings show that distinct microstructural features are obtained in dependence of the locally applied laser power. These features manifest themselves not only in terms of grain morphology, texture and hardness but also induce changes in the local electro-magnetic properties. The inscribed pattern can be non-destructively visualized by using an advanced eddy current technique.

Originality/value

Conventional copy protection basically consists in supplementary labelling or surface modification. In the present study, a new method is proposed for additively manufactured parts, overcoming the drawbacks of the former methods through process-induced microstructure manipulation. Slight alterations in the electro-magnetic material properties can be detected by advanced eddy current method allowing for identification of arbitrary and inimitable component information in additively manufactured parts.

Details

Rapid Prototyping Journal, vol. 22 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Available. Open Access. Open Access
Article
Publication date: 1 January 2019

Siraj K. K. and Azzah Al Maskari

The main purpose of this study was to evaluate students’ perception of blended learning instructional design in a Higher Education Institution (HEI) in the Sultanate of Oman. A…

4730

Abstract

The main purpose of this study was to evaluate students’ perception of blended learning instructional design in a Higher Education Institution (HEI) in the Sultanate of Oman. A course in a bachelor degree was offered using blended learning instructional mode, and students’ feedback was obtained on the impact of blended learning. The study was conducted in Ibra College of Technology, one of the seven colleges under the Ministry of Manpower in the Sultanate of Oman. A course in Business Strategy and HR Management was offered during Summer 2016 using a combination of traditional and online instructional design. A structured questionnaire was administered at the end of the semester to solicit feedback from students. The results of the study highlighted a positive attitude among students towards blended learning courses. The research stressed the requirements for proper infrastructure, training and development initiatives for staff and students, shift to a more focused practical assessment methods to measure the graduate attributes. Student engagement, learner autonomy, connection of learning to real life environments and flexibility all appeared to benefit from the blended learning course.

Details

Learning and Teaching in Higher Education: Gulf Perspectives, vol. 15 no. 2
Type: Research Article
ISSN: 2077-5504

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Article
Publication date: 15 February 2021

Lan Li, Tan Pan, Xinchang Zhang, Yitao Chen, Wenyuan Cui, Lei Yan and Frank Liou

During the powder bed fusion process, thermal distortion is one big problem owing to the thermal stress caused by the high cooling rate and temperature gradient. For the purpose…

497

Abstract

Purpose

During the powder bed fusion process, thermal distortion is one big problem owing to the thermal stress caused by the high cooling rate and temperature gradient. For the purpose of avoiding distortion caused by internal residual stresses, support structures are used in most selective laser melting (SLM) process especially for cantilever beams because they can assist the heat dissipation. Support structures can also help to hold the work piece in its place and reduce volume of the printing materials. The mitigation of high thermal gradients during the manufacturing process helps to reduce thermal distortion and thus alleviate cracking, curling, delamination and shrinkage. Therefore, this paper aims to study the displacement and residual stress evolution of SLMed parts.

Design/methodology/approach

The objective of this study was to examine and compare the distortion and residual stress properties of two cantilever structures, using both numerical and experimental methods. The part-scale finite element analysis modeling technique was applied to numerically analyze the overhang distortions, using the layer-by-layer model for predicting a part scale model. The validation experiments of these two samples were built in a SLM platform. Then average displacement of the four tip corners and residual stress on top surface of cantilever beams were tested to validate the model.

Findings

The validation experiments results of average displacement of the four tip corners and residual stress on top surface of cantilever beams were tested to validate the model. It was found that they matched well with each other. From displacement and residual stress standpoint, by introducing two different support structure, two samples with the same cantilever beam can be successfully printed. In terms of reducing wasted support materials, print time and high surface quality, sample with less support will need less post-processing and waste energy.

Originality/value

Numerical modeling in this work can be a very useful tool to parametrically study the feasibility of support structures of SLM parts in terms of residual stresses and deformations. It has the capability for fast prediction in the SLMed parts.

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Article
Publication date: 18 April 2016

Maciej Mazur, Martin Leary, Matthew McMillan, Joe Elambasseril and Milan Brandt

Additive manufacture (AM) such as selective laser melting (SLM) provides significant geometric design freedom in comparison with traditional manufacturing methods. Such freedom…

3837

Abstract

Purpose

Additive manufacture (AM) such as selective laser melting (SLM) provides significant geometric design freedom in comparison with traditional manufacturing methods. Such freedom enables the construction of injection moulding tools with conformal cooling channels that optimize heat transfer while incorporating efficient internal lattice structures that can ground loads and provide thermal insulation. Despite the opportunities enabled by AM, there remain a number of design and processing uncertainties associated with the application of SLM to injection mould tool manufacture, in particular from H13/DIN 1.2344 steel as commonly used in injection moulds. This paper aims to address several associated uncertainties.

Design/methodology/approach

A number of physical and numerical experimental studies are conducted to quantify SLM-manufactured H13 material properties, part manufacturability and part characteristics.

Findings

Findings are presented which quantify the effect of SLM processing parameters on the density of H13 steel components; the manufacturability of standard and self-supporting conformal cooling channels, as well as structural lattices in H13; the surface roughness of SLM-manufactured cooling channels; the effect of cooling channel layout on the associated stress concentration factor and cooling uniformity; and the structural and thermal insulating properties of a number of structural lattices.

Originality/value

The contributions of this work with regards to SLM manufacture of H13 of injection mould tooling can be applied in the design of conformal cooling channels and lattice structures for increased thermal performance.

Details

Rapid Prototyping Journal, vol. 22 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 16 March 2015

Christian Lindemann, Thomas Reiher, Ulrich Jahnke and Rainer Koch

This paper aims to present a methodology to help end-users to find appropriate part candidates for the use of the additive manufacturing (AM) technology. These shall be capable of…

2578

Abstract

Purpose

This paper aims to present a methodology to help end-users to find appropriate part candidates for the use of the additive manufacturing (AM) technology. These shall be capable of bringing AM into their businesses. The concept furthermore includes approaches for redesigning current available parts and helps to estimate the economic implications of the use of the technology.

Design/methodology/approach

The approach starts to discuss general economic aspects for the successful use of AM. While describing the introduction of new technologies into existing businesses, the importance of an appropriate part selection for AM is pointed out. A methodology for a part selection process is presented, and the different criteria are developed. An approach for a redesign of the selected parts, including the gathering of requirements, is given based on different sample parts. A variation of criteria to include measures for product piracy is highlighted.

Findings

The methodology has proven applicability in several research and industry projects in aerospace applications. Independent part selections from experts analyzed within a project of the European Space Agency had a 90 per cent overlap with the results. It allows companies with only basic AM knowledge to start a part screening for applicable AM candidates in their own company with a reasonable effort.

Originality/value

The methodology for the redesign process helps to identify the main functions of the products targeted and the relevant environment, so one can benefit from the various advantages that AM has to offer. The selection methodology helps to ask the right questions and to reduce the effort.

Details

Rapid Prototyping Journal, vol. 21 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 25 October 2019

Laura Boniotti, Stefano Foletti, Stefano Beretta and Luca Patriarca

Additive manufacturing (AM) enables the production of lightweight parts with complex shapes and small dimensions. Recent improvements in AM techniques have allowed a significant…

644

Abstract

Purpose

Additive manufacturing (AM) enables the production of lightweight parts with complex shapes and small dimensions. Recent improvements in AM techniques have allowed a significant growth of AM for industrial applications. In particular, AM is suitable for the production of materials shaped in lattice, which are very attractive for their lightweight design and their multi-functional properties. AM parts are often characterised by geometrical imperfections, residual porosity, high surface roughness which typically lead to stress/strain localisations and decreasing the resistance of the structure. This paper aims to focus on the study of the effects of geometrical irregularities and stress concentrations derived from them.

Design/methodology/approach

In this paper, several technique were combined: 3D tomography, experimental tests, digital image correlation and finite elements (FE) models based on both the as-designed and the as-manufactured geometries of lattice materials. The Digital Image Correlation technique allowed to measure local deformations in the specimen during the experimental test. The micro-computed tomography allowed to reconstruct the as-manufactured geometries of the specimens, from which the geometrical quality of the micro-structure is evaluated to run FE analyses.

Findings

Experimental and numerical results were compared by means of a stress concentration factor. This factor was calculated in three different specimens obtained from three-different printing processes to compare and understand their mechanical properties. Considering the as-designed geometry, it is not possible to model geometrical imperfections, and a FE model based on an as-manufactured geometry is needed. The results show that the mechanical properties of the printed samples are directly related to the statistical distribution of the stress concentration factor.

Originality/value

In this work, several techniques were combined to study the mechanical behaviour of lattice micro-structures. Lattice materials obtained by different selective laser melting printing parameters show different mechanical behaviours. A stress concentration factor can be assumed as a measure of the quality of these mechanical properties.

Details

Rapid Prototyping Journal, vol. 26 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

Available. Open Access. Open Access
Article
Publication date: 6 September 2022

Agnieszka Chmielewska, Bartlomiej Adam Wysocki, Elżbieta Gadalińska, Eric MacDonald, Bogusława Adamczyk-Cieślak, David Dean and Wojciech Świeszkowski

The purpose of this paper is to investigate the effect of remelting each layer on the homogeneity of nickel-titanium (NiTi) parts fabricated from elemental nickel and titanium…

1907

Abstract

Purpose

The purpose of this paper is to investigate the effect of remelting each layer on the homogeneity of nickel-titanium (NiTi) parts fabricated from elemental nickel and titanium powders using laser powder bed fusion (LPBF). In addition, the influence of manufacturing parameters and different melting strategies, including multiple cycles of remelting, on printability and macro defects, such as pore and crack formation, have been investigated.

Design/methodology/approach

An LPBF process was used to manufacture NiTi alloy from elementally blended powders and was evaluated with the use of a remelting scanning strategy to improve the homogeneity of fabricated specimens. Furthermore, both single melt and up to two remeltings were used.

Findings

The results indicate that remelting can be beneficial for density improvement as well as chemical and phase composition homogenization. Backscattered electron mode in scanning electron microscope showed a reduction in the presence of unmixed Ni and Ti elemental powders in response to increasing the number of remelts. The microhardness values of NiTi parts for the different numbers of melts studied were similar and ranged from 487 to 495 HV. Nevertheless, it was observed that measurement error decreases as the number of remelts increases, suggesting an increase in chemical and phase composition homogeneity. However, X-ray diffraction analysis revealed the presence of multiple phases regardless of the number of melt runs.

Originality/value

For the first time, to the best of the authors’ knowledge, elementally blended NiTi powders were fabricated via LPBF using remelting scanning strategies.

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Article
Publication date: 26 July 2021

Rajae Jemghili, Abdelmajid Ait Taleb and Mansouri Khalifa

Although many researchers have widely studied additive manufacturing (AM) as one of the most important industrial revolutions, few have presented a bibliometric analysis of the…

619

Abstract

Purpose

Although many researchers have widely studied additive manufacturing (AM) as one of the most important industrial revolutions, few have presented a bibliometric analysis of the published studies in this area. This paper aims to evaluate AM research trends based on 4607 publications most cited from year 2010 to 2020.

Design/methodology/approach

The research methodology is bibliometric indicators and network analysis, including analysis based on keywords, citation analysis, productive journal, related published papers and authors indicators. Two free available software were employed VOSviewer and Bibexcel.

Findings

Keywords analysis results indicate that among the AM processes, Selective Laser Melting and Fused Deposition Modeling techniques, are the two processes ranked on top of the techniques employed and studied with 35.76% and 20.09% respectively. The citation analysis by VOSviewer software, reveals that the medical applications field and the fabrication of metal parts are the areas that interest researchers greatly. Different new research niches, as pharmaceutical industry, digital construction and food fabrication are growing topics in AM scientific works. This study reveals that journals “Materials & design”, “Advanced materials”, “Acs applied materials & interfaces”, “Additive manufacturing”, “Advanced functional materials” and “Biofabrication” are the most productive and influential in AM scientific research.

Originality/value

The results and conclusions of this work can be used as indicators of trends in AM research and/or as prospects for future studies in this area.

Details

Rapid Prototyping Journal, vol. 27 no. 7
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 11 March 2024

Luisa Fernanda Manrique Molina, William Fernando Durán and Carlos Augusto Valencia

The purpose of this study is to generate knowledge about assessment methods in blended business education, which have become increasingly important to establish sustainable…

72

Abstract

Purpose

The purpose of this study is to generate knowledge about assessment methods in blended business education, which have become increasingly important to establish sustainable assessment practices that support knowledge acquisition for undergraduate students in business administration at a Colombian university.

Design/methodology/approach

For the analysis, a two groups comparison was performed using a nonequivalent control group design with a sample of 420 students. As this study wants to find insights to improve the knowledge on assessment topics in marketing research (MR) education, it was focused on the students from the business administration program. This study also uses individual scores from the state test as prior cognitive scores and the high school classification provided by the National Ministry of Education in Colombia (2012).

Findings

It was found that the variables that best predict performance on the MR course examinations were the mathematics skills and reading comprehension scores on the state test. The study also showed a better performance of female students on both assessment methods. There were no significant differences between the assessment methods or among the high school levels.

Research limitations/implications

One of the limitations of this study is the limited number of items on the tests. Additionally, the authors recommend conducting an analysis of the differences between the testing items to provide a detailed explanation of students’ performance when comparing computer-based testing and paper-and-pencil testing.

Practical implications

Further design of teaching material and assessments online and offline, based on local and regional marketing problems, is suggested. As the current text and readings are more oriented to the English-speaking contexts, most of the problems presented are oriented to multinational companies and brands.

Social implications

Insights into the skills required for future jobs provide valuable guidance (World Economic Forum, 2020). Essential skills for emerging roles, like data scientists, can find robust support within the MR course. To further enrich in-class and online exercises with Excel and SPSS, Colombian educators can leverage data sets obtained from sources like the national statistics office and international market intelligence databases available through the university’s library, including Passport and Statista. Engaging with authentic data sets provides students with a more profound understanding of practical applications in MR.

Originality/value

This approach facilitates the identification of key variables, such as assessment and cognitive abilities in math and reading, which predict students’ knowledge acquisition in MR. It not only offers insights into the relevant factors influencing learning in MR but also provides valuable feedback. Additionally, it suggests potential avenues for future research in this field.

Details

Journal of International Education in Business, vol. 17 no. 2
Type: Research Article
ISSN: 2046-469X

Keywords

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Article
Publication date: 3 July 2020

Ruben B.O. Acevedo, Klaudia Kantarowska, Edson Costa Santos and Marcio C. Fredel

This paper aims to generate a review of available techniques to measure Residual Stress (RS) in Ti6Al4V components made by Ti6Al4V.

898

Abstract

Purpose

This paper aims to generate a review of available techniques to measure Residual Stress (RS) in Ti6Al4V components made by Ti6Al4V.

Design/methodology/approach

State of the art; literature review in the field of Residual Stress measurement of Ti6Al4V parts made by selective laser melting (SLM).

Findings

Different Residual Stress measurement techniques were detailed, regarding its concept, advantages and limitations. Regarding all researched references, hole drilling (semi destructive) and X-ray diffraction (nondestructive) were the most cited techniques for Residual Stress measurement of Ti6Al4V parts made by SLM.

Originality/value

An extensive analysis of RS measurement techniques for Ti6Al4V parts made by SLM.

Details

Rapid Prototyping Journal, vol. 29 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

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