On the effect of irradiance on dimensional accuracy in multijet fusion additive manufacturing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mattia Mele ◽  
Giampaolo Campana ◽  
Gian Luca Monti
Keyword(s):  
Additive Manufacturing ◽  
Dimensional Accuracy ◽  
Crystallinity Degree ◽  
Content Type ◽  
Powder Bed ◽  
Polyamide 12 ◽  
Part Density ◽  
The Relationship ◽  
Am Processes

Purpose The amount of radiated energy is known to be a crucial parameter in powder-bed additive manufacturing (AM) processes. The role of irradiance in the multijet fusion (MJF) process has not been addressed by any previous research, despite the key role of this process in the AM industry. The aim of this paper is to explore the relationship between irradiance and dimensional accuracy in MJF. Design/methodology/approach An experimental activity was carried out to map the relationship between irradiance and dimensional accuracy in the MJF transformation of polyamide 12. Two specimens were used to measure the dimensional accuracy on medium and small sizes. The experiment was run using six different levels of irradiance. For each, the crystallinity degree and part density were measured. Findings Irradiance was found to be directly proportional to part density and inversely proportional to crystallinity degree. Higher irradiance leads to an increase in the measured dimensions of parts. This highlights a predominant role of the crystallisation degree and uncontrolled peripherical sintering, in line with the previous literature on other powder-bed AM processes. The results demonstrate that different trends can be observed according to the range of sizes.

A review of melt extrusion additive manufacturing processes: II. Materials, dimensional accuracy, and surface roughness

2015 ◽  
Vol 21 (3) ◽  
pp. 250-261 ◽  
Author(s):  
Brian N. Turner ◽  
Scott A Gold
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Product Design ◽  
Fused Deposition Modeling ◽  
Dimensional Accuracy ◽  
Design Parameters ◽  
Content Type ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
Am Processes

Purpose – The purpose of this paper is to critically review the literature related to dimensional accuracy and surface roughness for fused deposition modeling and similar extrusion-based additive manufacturing or rapid prototyping processes. Design/methodology/approach – A systematic review of the literature was carried out by focusing on the relationship between process and product design parameters and the dimensional and surface properties of finished parts. Methods for evaluating these performance parameters are also reviewed. Findings – Fused deposition modeling® and related processes are the most widely used polymer rapid prototyping processes. For many applications, resolution, dimensional accuracy and surface roughness are among the most important properties in final parts. The influence of feedstock properties and system design on dimensional accuracy and resolution is reviewed. Thermal warping and shrinkage are often major sources of dimensional error in finished parts. This phenomenon is explored along with various approaches for evaluating dimensional accuracy. Product design parameters, in particular, slice height, strongly impact surface roughness. A geometric model for surface roughness is also reviewed. Originality/value – This represents the first review of extrusion AM processes focusing on dimensional accuracy and surface roughness. Understanding and improving relationships between materials, design parameters and the ultimate properties of finished parts will be key to improving extrusion AM processes and expanding their applications.

scholarly journals A functional modeling approach for quality assurance in metal additive manufacturing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Gijeong Seo ◽  
Md. RU Ahsan ◽  
Yousub Lee ◽  
Jong-Ho Shin ◽  
Hyungjun Park ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Additive Manufacturing ◽  
Functional Design ◽  
Holistic View ◽  
Design Models ◽  
Content Type ◽  
Powder Bed ◽  
Critical Issues ◽  
New Research ◽  
Am Processes

Purpose Due to the complexity of and variations in additive manufacturing (AM) processes, there is a level of uncertainty that creates critical issues in quality assurance (QA), which must be addressed by time-consuming and cost-intensive tasks. This deteriorates the process repeatability, reliability and part reproducibility. So far, many AM efforts have been performed in an isolated and scattered way over several decades. In this paper, a systematically integrated holistic view is proposed to achieve QA for AM. Design/methodology/approach A systematically integrated view is presented to ensure the predefined part properties before/during/after the AM process. It consists of four stages, namely, QA plan, prospective validation, concurrent validation and retrospective validation. As a foundation for QA planning, a functional workflow and the required information flows are proposed by using functional design models: Icam DEFinition for Function Modeling. Findings The functional design model of the QA plan provides the systematically integrated view that can be the basis for inspection of AM processes for the repeatability and qualification of AM parts for reproducibility. Research limitations/implications A powder bed fusion process was used to validate the feasibility of this QA plan. Feasibility was demonstrated under many assumptions; real validation is not included in this study. Social implications This study provides an innovative and transformative methodology that can lead to greater productivity and improved quality of AM parts across industries. Furthermore, the QA guidelines and functional design models provide the foundation for the development of a QA architecture and management system. Originality/value This systematically integrated view and the corresponding QA plan can pose fundamental questions to the AM community and initiate new research efforts in the in-situ digital inspection of AM processes and parts.

scholarly journals Analysis of Density, Roughness, and Accuracy of the Atomic Diffusion Additive Manufacturing (ADAM) Process for Metal Parts

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4122 ◽  
Author(s):  
Manuela Galati ◽  
Paolo Minetola
Keyword(s):  
Additive Manufacturing ◽  
Layer Thickness ◽  
Dimensional Accuracy ◽  
Raw Material ◽  
Atomic Diffusion ◽  
Powder Bed ◽  
Metal Parts ◽  
Unique System ◽  
Am Processes ◽  
Metal Additive

Atomic Diffusion Additive Manufacturing (ADAM) is a recent layer-wise process patented by Markforged for metals based on material extrusion. ADAM can be classified as an indirect additive manufacturing process in which a filament of metal powder encased in a plastic binder is used. After the fabrication of a green part, the plastic binder is removed by the post-treatments of washing and sintering (frittage). The aim of this work is to provide a preliminary characterisation of the ADAM process using Markforged Metal X, the unique system currently available on the market. Particularly, the density of printed 17-4 PH material is investigated, varying the layer thickness and the sample size. The dimensional accuracy of the ADAM process is evaluated using the ISO IT grades of a reference artefact. Due to the deposition strategy, the final density of the material results in being strongly dependent on the layer thickness and the size of the sample. The density of the material is low if compared to the material processed by powder bed AM processes. The superficial roughness is strongly dependent upon the layer thickness, but higher than that of other metal additive manufacturing processes because of the use of raw material in the filament form. The accuracy of the process achieves the IT13 grade that is comparable to that of traditional processes for the production of semi-finished metal parts.

Role of burnout on job level, job satisfaction, and task performance

2017 ◽  
Vol 38 (5) ◽  
pp. 630-645 ◽  
Author(s):  
Won Ho Kim ◽  
Young-An Ra ◽  
Jong Gyu Park ◽  
Bora Kwon
Keyword(s):  
Job Satisfaction ◽  
Task Performance ◽  
Organizational Context ◽  
Content Type ◽  
Job Level ◽  
Mediating Role ◽  
Final Sample ◽  
The Relationship ◽  
And Task

Purpose The purpose of this paper is to examine the mediating role of burnout (i.e. exhaustion, cynicism, professional inefficacy) in the relationship between job level and job satisfaction as well as between job level and task performance. Design/methodology/approach The final sample included 342 Korean workers from selected companies. The authors employed the Hayes (2013) PROCESS tool for analyzing the data. Findings The results showed that all three subscales of burnout (i.e. exhaustion, cynicism, professional inefficacy) mediate the relationship between job level and job satisfaction. However, only two mediators (i.e. cynicism, professional inefficacy) indicated the mediating effects on the association between job level and task performance. Originality/value This research presented the role of burnout on the relationships between job level, job satisfaction, and task performance especially in South Korean organizational context. In addition to role of burnout, findings should prove helpful in improving job satisfaction and task performance. The authors provide implications and limitations of the findings.

Impact of perceived corporate social responsibility on attitudes and behaviors of pharmacists working in MNCs

Humanomics ◽  
2017 ◽  
Vol 33 (4) ◽  
pp. 453-469 ◽  
Author(s):  
Muhammad Khaleel ◽  
Shankar Chelliah ◽  
Sana Rauf ◽  
Muhammad Jamil
Keyword(s):  
Corporate Social Responsibility ◽  
Organizational Commitment ◽  
Supervisory Support ◽  
Content Type ◽  
Attitudes And Behaviors ◽  
Perceived Supervisory Support ◽  
And Behaviors ◽  
Corporate Social ◽  
The Relationship

Purpose This study aims to find out how corporate social responsibility (CSR) initiatives are perceived by pharmacists and how it influences employees’ organizational commitment and organizational citizenship behavior (OCB) and role of perceived supervisor support in the study. Design/methodology/approach Pharmacists of different hierarchical levels from five multinational pharmaceutical industries in Pakistan were selected as study samples. Data were collected from 136 pharmacists working in Punjab Region. PLS-SEM was used to test the hypotheses. Findings The results from this study found that CSR was a predictor of affective organizational commitment (AOC) and OCB. AOC fully mediates the relationship between CSR and OCB. While perceived supervisory support did not moderate the relationship between AOC and OCB. Pharmaceutical firms can promote commitment toward organization and OCBs by initiating CSR activities. Research limitations/implications This research is one of the innovative studies that empirically examine the predicting role of CSR and moderating role of perceived supervisory support on employees’ attitude and behaviors in the pharmaceutical companies’ context. Moreover, this research will also help the management by adopting CSR activities as core element in shaping employees attitudes and behaviors. Originality/value It is a significant study shifting the focus of research into organizational behavior context and further influences employee’s attitudes and behavior because of perceived CSR in the pharmacy industry.

Toward Metamodels for Composable and Reusable Additive Manufacturing Process Models

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Paul Witherell ◽  
Shaw Feng ◽  
Timothy W. Simpson ◽  
David B. Saint John ◽  
Pan Michaleris ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Metal Powder ◽  
Manufacturing Process ◽  
Process Model ◽  
Model Development ◽  
Process Models ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Future Work ◽  
Am Processes

In this paper, we advocate for a more harmonized approach to model development for additive manufacturing (AM) processes, through classification and metamodeling that will support AM process model composability, reusability, and integration. We review several types of AM process models and use the direct metal powder bed fusion AM process to provide illustrative examples of the proposed classification and metamodel approach. We describe how a coordinated approach can be used to extend modeling capabilities by promoting model composability. As part of future work, a framework is envisioned to realize a more coherent strategy for model development and deployment.

Overconfidence of vocational education students when entering higher education

2015 ◽  
Vol 57 (4) ◽  
pp. 429-447 ◽  
Author(s):  
Mark P. Bowden ◽  
Subhash Abhayawansa ◽  
John Bahtsevanoglou
Keyword(s):  
Higher Education ◽  
Self Efficacy ◽  
Further Education ◽  
Small Sample ◽  
First Year ◽  
Education Students ◽  
Content Type ◽  
The Relationship ◽  
Practical Implications

Purpose – There is evidence that students who attend Technical and Further Education (TAFE) prior to entering higher education underperform in their first year of study. The purpose of this paper is to examine the role of self-efficacy in understanding the performance of students who completed TAFE in the previous year in a first year subject of microeconomics in a dual sector university in Melbourne, Australia. Design/methodology/approach – The study utilises data collected by surveys of 151 students. Findings – A student’s self-efficacy is positively associated with their marks in a first year subject of microeconomics. However, the relationship between final marks and self-efficacy is negative for those students who attended TAFE in the previous year suggesting that they suffer from the problem of overconfidence. When holding self-efficacy constant, using econometric techniques, TAFE attendance is found to be positively related to final marks. Research limitations/implications – The findings are exploratory (based on a small sample) and lead to a need to conduct cross institutional studies. Practical implications – The research points to the need for early interventions so that TAFE students perform well in their first year of higher education. It also points to potential issues in the development of Victorian Certificate of Applied Learning (VCAL) programs. Originality/value – To the best of the authors’ knowledge, this is the first paper to examine the inter-related impact of attendance at TAFE in the previous year and self-efficacy on the subsequent academic performance of TAFE students.

Managing different forms of distances in Dutch healthcare organizations

2015 ◽  
Vol 29 (7) ◽  
pp. 1080-1097
Author(s):  
Annemiek Stoopendaal
Keyword(s):  
Design Methodology ◽  
Healthcare Organization ◽  
Ethnographic Study ◽  
Healthcare Organizations ◽  
Content Type ◽  
Daily Work ◽  
Healthcare Executives ◽  
Governance Practices ◽  
The Relationship

Purpose – Dichotomous “gap” thinking about professionals and managers has important limits. The purpose of this paper is to study the specific ontology of “the gap” in which different forms of distances are defined. Design/methodology/approach – In order to deepen the knowledge of the actual day-to-day tasks of Dutch healthcare executives an ethnographic study of the daily work of Dutch healthcare executives and an ontological exploration of the concept “gap” was provided. The study empirically investigates the meaning given to the concept of “distance” in healthcare governance practices. Findings – The study reveals that healthcare executives have to fulfil a dual role of maintaining distance and creating proximity. Coping with different forms of distances seems to be an integral part of their work. They make use of four potential mechanisms to cope with distance in their healthcare organization practices. Originality/value – The relationship between managers and professionals is often defined as a dichotomous gap. The findings in this research suggest a more dynamic picture of the relationship between managers and professionals than is currently present in literature. This study moves “beyond” the gap and investigates processes of distancing in-depth.

The dimensional linkage between public service motivation and innovative behavior in public sector institutions; the mediating role of psychological empowerment

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Muhammad Asim Rafique ◽  
Yumei Hou ◽  
Muhammad Adnan Zahid Chudhery ◽  
Nida Gull ◽  
Syed Jameel Ahmed
Keyword(s):  
Public Sector ◽  
Public Service ◽  
Psychological Empowerment ◽  
Public Service Motivation ◽  
Innovative Behavior ◽  
Content Type ◽  
Mediating Role ◽  
Relationship Of ◽  
The Relationship

PurposeInnovations are imperative for organizational growth and sustainability. This study focuses on the employees' innovative behavior, a source of organizational innovations, which has received substantial attention from the researchers. Based on the psychological empowerment theory, the study exposes the effect of the various dimensions of public service motivation (PSM) on employees' innovative behavior (IB) in public sector institutions especially in the context of developing countries such as Pakistan. Moreover, the study also investigates the mediating role of psychological empowerment (PSE) between the dimensions of PSM and IB.Design/methodology/approachThis study used the cross-sectional research design. By using random sampling, the adapted survey questionnaires were used to collect data from 346 faculty members of public sector universities located in provincial capitals of Pakistan. A partial least square–structural equation modeling (PLS-SEM) tool was used to assess the proposed hypotheses through SMART-PLS software.FindingsResults revealed that attraction to policymaking (APM), compassion (COM), self-sacrifice (SS) have a significant impact on employees' PSE and their innovative behavior, while the relationship of commitment to the public interest (CPI) with PSE and IB was found insignificant. Moreover, PSE partially mediated the relationship between PSM dimensions and employees' IB.Originality/valueThere was a scarcity of research on IB especially in public sector institutions such as academia. This study theoretically contributed to the literature by providing a refined picture in assessing the proposed relationship of the constructs. This is also one of the original studies that examine the relationship between the dimensions of PSM and IB.

The role of robotics in additive manufacturing: review of the AM processes and introduction of an intelligent system

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
J. Norberto Pires ◽  
Amin S. Azar ◽  
Filipe Nogueira ◽  
Carlos Ye Zhu ◽  
Ricardo Branco ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Intelligent System ◽  
Material Selection ◽  
High Strength Steels ◽  
Industrial Applications ◽  
Layer By Layer ◽  
Content Type ◽  
Functional Components

Purpose Additive manufacturing (AM) is a rapidly evolving manufacturing process, which refers to a set of technologies that add materials layer-by-layer to create functional components. AM technologies have received an enormous attention from both academia and industry, and they are being successfully used in various applications, such as rapid prototyping, tooling, direct manufacturing and repair, among others. AM does not necessarily imply building parts, as it also refers to innovation in materials, system and part designs, novel combination of properties and interplay between systems and materials. The most exciting features of AM are related to the development of radically new systems and materials that can be used in advanced products with the aim of reducing costs, manufacturing difficulties, weight, waste and energy consumption. It is essential to develop an advanced production system that assists the user through the process, from the computer-aided design model to functional components. The challenges faced in the research and development and operational phase of producing those parts include requiring the capacity to simulate and observe the building process and, more importantly, being able to introduce the production changes in a real-time fashion. This paper aims to review the role of robotics in various AM technologies to underline its importance, followed by an introduction of a novel and intelligent system for directed energy deposition (DED) technology. Design/methodology/approach AM presents intrinsic advantages when compared to the conventional processes. Nevertheless, its industrial integration remains as a challenge due to equipment and process complexities. DED technologies are among the most sophisticated concepts that have the potential of transforming the current material processing practices. Findings The objective of this paper is identifying the fundamental features of an intelligent DED platform, capable of handling the science and operational aspects of the advanced AM applications. Consequently, we introduce and discuss a novel robotic AM system, designed for processing metals and alloys such as aluminium alloys, high-strength steels, stainless steels, titanium alloys, magnesium alloys, nickel-based superalloys and other metallic alloys for various applications. A few demonstrators are presented and briefly discussed, to present the usefulness of the introduced system and underlying concept. The main design objective of the presented intelligent robotic AM system is to implement a design-and-produce strategy. This means that the system should allow the user to focus on the knowledge-based tasks, e.g. the tasks of designing the part, material selection, simulating the deposition process and anticipating the metallurgical properties of the final part, as the rest would be handled automatically. Research limitations/implications This paper reviews a few AM technologies, where robotics is a central part of the process, such as vat photopolymerization, material jetting, binder jetting, material extrusion, powder bed fusion, DED and sheet lamination. This paper aims to influence the development of robot-based AM systems for industrial applications such as part production, automotive, medical, aerospace and defence sectors. Originality/value The presented intelligent system is an original development that is designed and built by the co-authors J. Norberto Pires, Amin S. Azar and Trayana Tankova.

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