Search results

This paper aims to study the effects of part orientation during the 3D printing process, particularly to the case of using continuous digital light processing (cDLP) technology.

The effects of print orientation on the print accuracy of microstructural features were assessed using microCT imaging and mechanical properties of cDLP microporous scaffolds were characterized under simple compression and complex biaxial loading. Resin viscosity was also quantified to incorporate this factor in the printing discussion.

The combined effect of print resin viscosity and the orientation and spacing of pores within the structure alters how uncrosslinked resin flows within the construct during cDLP printing. Microstructural features in horizontally printed structures exhibited greater agreement to the design dimensions than vertically printed constructs. While cDLP technologies have the potential to produce mechanically isotropic solid constructs because of bond homogeneity, the effect of print orientation on microstructural feature sizes can result in structurally anisotropic porous constructs.

This work is useful to elucidate on the specific capabilities of 3D printing cDLP technology. The orientation of the part can be used to optimize the printing process, directly altering parameters such as the supporting structures required, print time, layering, shrinkage or surface roughness. This study further detailed the effects on the mechanical properties and the print accuracy of the printed scaffolds.

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.

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

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.

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.

This paper aims to investigate the views of employees on the motives behind frequently reported fraudulent activities at the workplace. Using the fraud triangle theory (FTT) as the theoretical lens, the study examines the effect of pressure, opportunity and rationalization on fraudulent acts by employees at the workplace.

The study follows a correlational quantitative approach using questionnaires as the main data collection tool. A total of 243 valid responses from employees working in different state-owned enterprises in Ghana were used in the empirical analysis. The hypothesized relationships of the study were tested using the partial least square-structural equation modelling technique.

The results from the structural analysis showed that pressure, rationalization and opportunity are important in explaining why employees engage in fraudulent activities at the workplace.

The findings do not only provide empirical support for the applicability of the FTT in the Ghanaian context but most importantly offer some useful insights into the fraud discourse from the public sector workers’ perspective.

This paper aims to formulate a new metal working fluid (MWF) composition including some eco-friendly emulsifiers, corrosion inhibitor, biocide, and non- edible vegetable oil (castor oil) as the base oil. To achieve this aim, five MWFs with different hydrophilic–lipophilic balance (HLB) value as 10, 9.5, 9, 8.5 and 8 were prepared to identify the optimum HLB value that gives a highly stable oil-in-water emulsion. The performance of castor oil based MWF was evaluated using tool chip tribometer and drill dynamometer. The surface morphology of steel disc and friction pin was performed using scanning electron microscope (SEM) and 3D profilometer. The results revealed that the use of the prepared cutting fluid (E1) caused the cutting force to decrease from 500 N for dry high-speed steel sample to 280N, while the same value for a commercial cutting fluid (COM) was recorded as 340 N at drilling speed and cutting feed force as 1120 rpm and 4 mm/min., respectively.

A castor oil-based metalworking fluid was prepared using nonionic surfactants. The composition of the metalworking fluid was further optimized by adding performance-enhancing additives. The performance of castor oil based MWF was analyzed using Tool chip tribometer and Drill dynamometer. The surface morphology of steel ball and a disc was done using 3D profilometer and SEM.

Studies revealed that castor oil-based MWF having Monoethanolamine (MEA) as corrosion inhibitor was found to be highly stable. The drilling dynamometer and tool chip tribometer studies showed that castor oil-based MWF performance was comparable to that of commercial MWF.

This study aims to explore the performance of the castor oil based metalworking fluid (MWF) using tool chip tribometer and drill dynamometer.

The conventional MWFs are petroleum derives and are unsustainable. Use of non-edible plant-based oils for preparing the MWF will not only be conserved environment but also add value addition to agricultural crops.

The social Implications is aiming to decrease the environmental impact that results from the using of mineral cutting fluids.

The originality of this work is to replace the mineral oil and synthetic oil based cutting fluids with more eco-friendly alternatives one. In addition, the investigation will focus on developing functional additives required for cutting fluids which are environmentally benign.

The curved and tribologically highly stressed surfaces of bearing components pose a major challenge for steel alloys or tribological resistant coatings like tetrahedral amorphous carbon (ta-C) coatings which in particular have an increased risk of delamination due to the significantly increased residual stresses. A possibility to prevent coating failure is the use of dopants while maintaining or even increasing tribological properties. This study aims to compare the tribological behavior of several doped diamond-like-carbon coatings with an undoped ta-C coating under varying slip conditions and Hertzian pressure up to 1800 MPa.

For this purpose, the tribological behavior was studied using of a ball-on-disc tribometer and a two-disc test rig under mixed/boundary conditions. The tests were conducted with coated specimens against uncoated 100Cr6 steel. Additionally, the influence of lubrication additives was studied due to the use of two fully formulated PAO-based oils, one without and one with molybdenum containing additives. The friction was measured in situ, and the wear was analyzed trough laser scanning microscopy and tactile measurement.

It was shown that the use of doped ta-C coatings exhibited a tendency for a more favorable tribological behavior compared to undoped ta-C coatings, with no general dependence on the lubricants used. The use of the most suitable coatings reduced the wear of the steel counter-body considerably.

To the best of the authors’ knowledge, this is the first approach of testing the tribological behavior of these doped ta-C coatings, developed for friction efficiency, in dependency on lubrication additives under the given load collective. The approach is relevant to determine whether the friction reduction and the wear inhibition of these coatings are suitable for higher contact pressures and load cycles.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2022-0336/

This paper aims to investigate the prevalence of asset misappropriation at the workplace and examines the dominant factors that influence individuals to misappropriate assets at the workplace. Relying on the most recent theory on fraud (the stimulus/pressure, capability, opportunity, rationalization and ego (S.C.O.R.E. model) as the theoretical basis, the study examines the effect of pressure, rationalization, capability, opportunity/strength of internal control system and ego on asset misappropriation at the workplace while controlling for the effect of ethical values.

A total of 883 valid responses from individuals working in various organizations in Ghana were collected by means of a self-administered questionnaire. The hypothesized relationships of the study were tested by means of a structural model analysis using the partial least square based structural equation modelling technique.

Results from the structural model analysis demonstrate that individuals misappropriate assets at their workplace due to pressures they face, their ability to rationalize their actions as not wrong, their capabilities and their egos. The results, however, indicate that the extent to which an individual will misappropriate asset depends, to a large extent, on the person’s perception of the strength of internal control mechanisms at the workplace. The findings of the study make significant contributions to the fraud discourse.

Theoretically, the study is among the first to provide empirical support for the applicability of the S.C.O.R.E. model in the fraud literature. Again, this study extends knowledge on occupational fraud literature by examining an area that has received the least research attention: asset misappropriation. The study also highlights the important role of internal controls in reducing the occurrence of asset misappropriation at the workplace.

This paper aims to present a model of the employability confidence of graduates using employability skills. The purpose of the study is twofold: to identify to what extent self-perceived employability skills (input employability) influence the employability confidence of students/graduates (output employability) and to identify if there are determinant relationships between categories of employability skills.

The researchers for this study built and tested an employability confidence model which included seven constructs. Six focussed on employability skills “professional skills, transferable individual skills, transferable social skills, personal qualities, job seeking skills and corporate work-related skills”, while the last one focussed on employability confidence, seen as the students’/graduates’ self-reliance for getting and maintaining a job. The model was refined using structural equation modelling (with SmartPLS 3 SEM software) and was tested by empirically, analysing a sample of participants studying business.

The results illustrated that four categories of skills (personal qualities, professional skills, job seeking skills and transferable social skills) have a positive and significant influence on students’/graduates’ employability confidence, while individual transferable skills and corporate-related skills do not have a significant influence on employability confidence.

The study contributed to the exiting literature by proposing a new model and measurement instrument that links input employability (individual employability skills) with output employability (employability confidence). The model emphasizes the complete range of individual employability skills, the types of skills that are in the control of the individual. It also contributed by collecting data from a less studied country and region, Romania, that can be considered relevant for Central and Eastern Europe due to similar economic, political, cultural and historical characteristics.

From a practical point of view, the results can be of interest to individuals, to universities and the teaching staff, to organizations and their human resource specialists, and to public administrators, as they all can act to support the development of individual employability skills, thereby helping to increase the employability confidence of individuals.

The study contributed to the exiting literature not only by proposing a new conceptual model to analyse employability confidence but also by collecting data from a less studied region, Romania, that can be considered relevant for Central and Eastern Europe due to similar economic, political, cultural and historical characteristics.

This study aims to share experiences of an easy to adapt service-learning approach in a graduate course on life cycle assessment (LCA). Specifically, it reports on how students helped the university’s cafeteria to assess meals by conducting an LCA for 25 meals and identifying environmental hotspots.

A descriptive case study of a graduate course at Ulm University is presented. The course included lectures and problem-based exercises, both theoretical and software assisted. A course evaluation was conducted during the course and one year after completion to poll improvement potentials, as well as its impacts on students’ everyday life.

It was found that although it was the first LCA for all students, the resulting LCA information of 25 different meals were homogeneous, comparable to the scientific literature and beneficial to the cafeteria’s sustainable development strategy. The concept of service-learning had a higher impact on students’ motivation than a good grade and active-learning is explicitly requested by students. The course design sensitized students to the real-life problems of LCA and made their consumption patterns more elaborate and ecological. Furthermore, this digitization of higher education could be carried out with only minor changes in the present COVID-19 pandemic situation.

As the subject of service-learning in natural sciences is still expandable, this study presents an easy to adapt case study on how to integrate such an approach into university curricula dominated by traditional learning. To the best of the authors’ knowledge, this case study presents the first published LCA university course explicitly describing and evaluating a service-learning approach. The topic touches the everyday lives of students, allows comparisons between different student groups, is easily scalable to different group sizes and credits, and supports learning both how to study in small groups and cooperation between groups to ensure comparability of LCA results.

This paper aims to address the coating and compound analysis of diamond-like carbon (DLC) on steel, to understand the frictional behavior in tribological gear systems presented in paper Part I. Here, the Ti and Zr modified DLC coating architectures are analyzed regarding their chemical, mechanical and thermophysical properties. The results represent a systematic analysis of the thermal insulating effect in tribological contact of DLC coated gears.

The approach was to evaluate the effect of the substitution of Zr through Ti at the reference coating ZrCg to TiCg and the effect on thermophysical properties. Furthermore, the influence of different carbon and hydrogen contents on the coating and compound properties was analyzed. Therefore, different discrete Ti or Zr containing DLC coatings were deposited on an industrial coating machine. Thereby the understanding of the microstructure and chemical composition of the reference coatings is increased.

Results prove comparable mechanical properties of metal modified DLC independent of differences in chemical compositions. Moreover, the compound adhesion between TiC_g/16MnCr5E was improved compared to ZrC_g/16MnCr5E. The effect of hydrogen content Ψ and carbon content x_c on the thermophysical properties is limited by Ψ = 18 at.% and x_c = 90 at.%.

The findings of the combined papers Part I and II show a high potential for industrial application of DLC on gears. Based on the results DLC coatings and gears can be tailored to each other.

Systematic analysis of DLC coatings were conducted to evaluate the effect of titanium, carbon and hydrogen on thermophysical properties.