Design and optimization of projection stereolithography additive manufacturing system with multi-pass scanning

2021 ◽  
Vol 27 (3) ◽  
pp. 636-642
Author(s):  
Qin Qin ◽  
Jigang Huang ◽  
Jin Yao ◽  
Wenxiang Gao
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing System ◽  
Content Type ◽  
Design And Optimization ◽  
Compensation Algorithm ◽  
The Poor ◽  
Building Area ◽  
Projection Stereolithography ◽  
Stitching Errors

Purpose Scanning projection-based stereolithography (SPSL) is a powerful technology for additive manufacturing with high resolution as well as large building area. However, the surface quality of stitching boundary in an SPSL system has been rarely studied, and no positive settlement was proposed to address the poor stitching quality. This paper aims to propose an approach of multi-pass scanning and a compensation algorithm for multi-pass scanning process to address the issue of poor stitching quality in SPSL systems. Design/methodology/approach The process of multi-pass scanning is realized by scanning regions repeatedly, and the regions can be cured simultaneously because of the very short repeat exposure time and very fast scanning. Then, the poor stitching quality caused by the non-simultaneous curing can be eliminated. Also, a compensation algorithm is designed for multi-pass scanning to reduce the stitching errors. The validity of multi-pass scanning is verified by curing depth test, while the performance of multi-pass scanning as well as proposed compensation algorithm is demonstrated by comparing with that of a previous SPSL system. Findings The results lead to a conclusion that multi-pass scanning with its compensation algorithm is an effective approach to improve the stitching quality of an SPSL system. Practical implications This study can provide advice for researchers to achieve the satisfactory surface finish with SPSL technology. Originality/value The authors proposed a process of multi-pass scanning as well as a compensation algorithm for SPSL additive manufacturing (system to improve the stitching quality, which has rarely been studied in previous work.

Managed care Medicaid

2017 ◽  
Vol 11 (2) ◽  
pp. 198-210 ◽  
Author(s):  
William Trombetta
Keyword(s):  
Health Care ◽  
Managed Care ◽  
Health Care Delivery ◽  
Care Delivery ◽  
Care Quality ◽  
Market Segment ◽  
Economic Aspects ◽  
Content Type ◽  
The Poor

Purpose Providing health care to the poor is evolving in the new US marketplace. The Affordable Care Act has set goals enhancing access to health care, lowering costs and improving patient outcomes. A key segment in this evolution is the most vulnerable health-care population of all: Medicaid. This paper aims to provide a general review of how providing health care to Medicaid patients is changing including how socio-economic aspects of this vulnerable population affects the quality of the health care provided. Design/methodology/approach The paper is entirely secondary research; no primary research has been conducted. Findings Managed care Medicaid provides a risk-based model to treating a vulnerable health-care market segment. The jury is still out on whether managed care Medicaid (MCM) is improving health-care quality and saving cost, but the provision of health care to the Medicaid segment is definitely shifting from a fee-for-service model to value based payment. Very recent developments of new health-care delivery approaches present a positive outlook for improving quality and containing costs going forward. Research limitations/implications At this stage, whether or not MCM saves money or provides better health-care quality to this vulnerable population is a work in progress. Health-care marketing can impact socio-economic aspects of health care for the poor. There is a need to follow up on the positive results being documented in demonstration health-care delivery models. Practical implications At this point, there has been no long-term study of whether managed care Medicaid offers better quality of health care and cost savings. The research to date suggest that the quality of health-care delivery to the poor is improving at a lower cost to payers. Social implications Medicaid patients are an underserved market segment. Managed care Medicaid offers a new model that has the potential to provide quality care at acceptable cost. Critical to this vulnerable market segment is the need to integrate socio-economic aspects of the population with the delivery of health care. Originality/value There has been very little discussion of Medicaid overall in the marketing literature, much less any discussion of managed care Medicaid.

scholarly journals The flexibility of industrial additive manufacturing systems

2018 ◽  
Vol 38 (12) ◽  
pp. 2313-2343 ◽  
Author(s):  
Daniel R. Eyers ◽  
Andrew T. Potter ◽  
Jonathan Gosling ◽  
Mohamed M. Naim
Keyword(s):  
Additive Manufacturing ◽  
Operations Management ◽  
Manufacturing Systems ◽  
Manufacturing System ◽  
Detailed Examination ◽  
Multiple Sources ◽  
Content Type ◽  
Commercial Practice ◽  
Systems Perspective ◽  
Manufacturing Operations

Purpose Flexibility is a fundamental performance objective for manufacturing operations, allowing them to respond to changing requirements in uncertain and competitive global markets. Additive manufacturing machines are often described as “flexible,” but there is no detailed understanding of such flexibility in an operations management context. The purpose of this paper is to examine flexibility from a manufacturing systems perspective, demonstrating the different competencies that can be achieved and the factors that can inhibit these in commercial practice. Design/methodology/approach This study extends existing flexibility theory in the context of an industrial additive manufacturing system through an investigation of 12 case studies, covering a range of sectors, product volumes, and technologies. Drawing upon multiple sources, this research takes a manufacturing systems perspective that recognizes the multitude of different resources that, together with individual industrial additive manufacturing machines, contribute to the satisfaction of demand. Findings The results show that the manufacturing system can achieve seven distinct internal flexibility competencies. This ability was shown to enable six out of seven external flexibility capabilities identified in the literature. Through a categorical assessment the extent to which each competency can be achieved is identified, supported by a detailed explanation of the enablers and inhibitors of flexibility for industrial additive manufacturing systems. Originality/value Additive manufacturing is widely expected to make an important contribution to future manufacturing, yet relevant management research is scant and the flexibility term is often ambiguously used. This research contributes the first detailed examination of flexibility for industrial additive manufacturing systems.

Brazil's private higher education will face shake-up

2016 ◽  
Keyword(s):  
Higher Education ◽  
Private Education ◽  
Poor Quality ◽  
Drop Out ◽  
Private Higher Education ◽  
State Universities ◽  
Education Students ◽  
Content Type ◽  
The Poor

Subject The outlook for higher education. Significance In the context of the worst recession since the 1930s, Brazilian higher education students are reconsidering their financial priorities. This has brought instability to the previously expanding market for private higher education, one of the most promising sectors during the years of economic expansion between the mid-2000s and early 2010s. Impacts A 50% cut in government-subsidised loans to students will further reduce Brazil's potential to improve its human capital. Shares in large private higher education conglomerates are recovering but are below their peak valuations reached in the early 2010s. The poor quality of much private education will gradually force improvements or loss of students to state universities. In turn, poor secondary education and high drop-out rates will remain obstacles to better-quality higher education.

Humming noise reduction of ceiling fan in the mass production applying DMAIC-six sigma approach

2020 ◽  
Vol 18 (1) ◽  
pp. 106-121
Author(s):  
Rubel Ahammed ◽  
Md. Zahid Hasan
Keyword(s):  
Six Sigma ◽  
Hypothesis Test ◽  
Process Condition ◽  
Poor Quality ◽  
Air Gap ◽  
Content Type ◽  
The Poor ◽  
And Control ◽  
Six Sigma Approach

Purpose Success and business reputation depend upon the quality of products where product quality depends upon the capability of a process, yield value and sigma score, etc. Poor quality of ceiling fan and mass rejection from quality check resulted in an alarming amount of cost for rework. As a result, the fulfillment of the production target was getting difficult day by day. The main purpose of this research is to identify the crucial causes for humming noise of ceiling fans and control it to a tolerable level so that maximum quality can be achieved. Design/methodology/approach The poor quality of ceiling fans was determined from the Pareto analysis of the define, measure, analyze, improve and control model which was humming noise during running and further actions were undertaken regarding the reduction of the humming noise. Project charter was formed before initiating the measure phase to study the suppliers, inputs, processes, outputs and customers diagram with process parameters and existing noise data were collected from random samples to determine the rolled throughput yield (94.95% existing) and existing sigma score which value of 3.14 and also the poor value (1.05) of process potential index implied that the process condition was below standard (<1.33) and need to be improved badly. Then root causes analysis and relationship diagram was prepared to identify the possible causes and with the design of experiments and correlation analysis, it was clear that the air gap between the stator and rotor was the main culprit behind the humming noise. Findings The minimum value of air gap was determined from boxplot analysis which was 0.2 mm–0.225 mm and the corresponding mean, the minimum and maximum value of sound level in dB (37.5–40.3 dB) for 0.225 mm air gap with the watt consumption (83 w) from the hypothesis test for the corresponding air gap. Finally, the updated sigma score and process capability analysis were performed with control charts to show the comparison after applying the DMAIC-six sigma methodology. The final sigma score was 5.1 which indicates a significant improvement of the process with the capability of saving US$23,438/year caused by the poor quality of ceiling fans. Practical implications Only quantitative values of the causes behind the humming noise were possible to identify. Other trivial many causes elimination might improve the sigma score closer to 6.00. The final sigma score that was achieved from this research was sustainable. Originality/value A structural approach with proper data analysis and application of various tools to detect the actual cause behind the humming noise of ceiling fans with numerical value has not been found in any literature. This research study can be a valuable asset for ceiling fan mass producers.

scholarly journals Robotic additive manufacturing system for dynamic build orientations

2020 ◽  
Vol 26 (4) ◽  
pp. 659-667
Author(s):  
Nicholas R. Fry ◽  
Robert C. Richardson ◽  
Jordan H. Boyle
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Design Methodology ◽  
Degrees Of Freedom ◽  
Manufacturing System ◽  
Print Quality ◽  
Orientation Relationships ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Build Orientation

Purpose This paper aims to present a multi-axis additive robot manufacturing system (ARMS) and demonstrate its beneficial capabilities. Design/methodology/approach ARMS was constructed around two robot arms and a fused filament fabrication (FFF) extruder. Quantitative experiments are conducted to investigate the effect of printing at different orientations with respect to gravity, the effect of dynamically changing build orientation with respect to the build tray when printing overhanging features, the effect of printing curved parts using curved, conformal layers. These capabilities are combined to print an integrated demonstrator showing potential practical benefits of the system. Findings Orientation with respect to gravity has no effect on print quality; dynamically changing build orientation allows overhangs up to 90° to be cleanly printed without support structures; printing an arch with conformal layers significantly increases its strength compared to conventional printing. Research limitations/implications The challenge of automatic slicing algorithms has not been addressed for multi-axis printing. It is shown that ARMS could eventually enable printing of fully-functional prototypes with embedded components. Originality/value This work is the first to prove that the surface roughness of an FFF part is independent of print orientation with respect to gravity. The use of two arms creates a novel system with more degrees of freedom than existing multi-axis printers, enabling studies on printing orientation relationships and printing around inserts. It also adds to the emerging body of multi-axis literature by verifying that curved layers improve the strength of an arch which is steeply curved and printed with the nozzle remaining normal to the curvature.

Additive manufacturing technology in dental education

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sven Maricic ◽  
Daniela  Kovacevic Pavicic ◽  
Barbara Ptacnik ◽  
Romina Prziklas Druzeta
Keyword(s):  
Additive Manufacturing ◽  
New Technologies ◽  
Dental Education ◽  
Dental Students ◽  
Additive Technologies ◽  
Additive Technology ◽  
Educational Model ◽  
Content Type ◽  
Computer Aided

Purpose This study aims to develop a specialized and economically feasible educational model using a combination of conventional approach and additive technology with a precision that proves to be sufficient for educational use. With the use of computer-aided design/computer-aided manufacturing models in educational stages, the possibility of infectious diseases transmission can be significantly reduced. Design/methodology/approach The proposed process involves the planning and development of specialized anatomical three-dimensional (3D) models and associated structures using omnipresent additive technologies. A short survey was conducted among dental students about their knowledge of applying additive technologies in dental medicine and their desire to implement such technologies into existing curricula. Findings The results revealed how an educational 3D model can be developed by optimizing the mesh parameters to reduce the total number of elements while maintaining the quality of the geometric structure. The survey results demonstrated that the willingness to adapt to new technologies is increasing (p < 0.001) among students with a higher level of education. A series of recent studies have indicated that the lack of knowledge and the current skill gap remain the most significant barriers to the wider adoption of additive manufacturing. Practical implications An economically feasible, realistic anatomical educational model in the field of dental medicine was established. Additive technology is a key pillar of new specialized-knowledge digital skills for the enhancement of dental training. Originality/value The novelty of this study is the introduction of a 3D technology for promoting an economically feasible model, without compromising the quality of dental education.

Comparing environmental impacts of additive manufacturing vs traditional machining via life-cycle assessment

2015 ◽  
Vol 21 (1) ◽  
pp. 14-33 ◽  
Author(s):  
Jeremy Faludi ◽  
Cindy Bayley ◽  
Suraj Bhogal ◽  
Myles Iribarne
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Additive Manufacturing ◽  
Environmental Impacts ◽  
Surface Finish ◽  
Numerical Control ◽  
Cutting Fluid ◽  
Content Type ◽  
Electricity Use

Purpose – The purpose of this study is to compare the environmental impacts of two additive manufacturing machines to a traditional computer numerical control (CNC) milling machine to determine which method is the most sustainable. Design/methodology/approach – A life-cycle assessment (LCA) was performed, comparing a Haas VF0 CNC mill to two methods of additive manufacturing: a Dimension 1200BST FDM and an Objet Connex 350 “inkjet”/“polyjet”. The LCA’s functional unit was the manufacturing of two specific parts in acrylonitrile butadiene styrene (ABS) plastic or similar polymer, as required by the machines. The scope was cradle to grave, including embodied impacts, transportation, energy used during manufacturing, energy used while idling and in standby, material used in final parts, waste material generated, cutting fluid for CNC, and disposal. Several scenarios were considered, all scored using the ReCiPe Endpoint H and IMPACT 2002+ methodologies. Findings – Results showed that the sustainability of additive manufacturing vs CNC machining depends primarily on the per cent utilization of each machine. Higher utilization both reduces idling energy use and amortizes the embodied impacts of each machine. For both three-dimensional (3D) printers, electricity use is always the dominant impact, but for CNC at maximum utilization, material waste became dominant, and cutting fluid was roughly on par with electricity use. At both high and low utilization, the fused deposition modeling (FDM) machine had the lowest ecological impacts per part. The inkjet machine sometimes performed better and sometimes worse than CNC, depending on idle time/energy and on process parameters. Research limitations/implications – The study only compared additive manufacturing in plastic, and did not include other additive manufacturing technologies, such as selective laser sintering or stereolithography. It also does not include post-processing that might bring the surface finish of FDM parts up to the quality of inkjet or CNC parts. Practical implications – Designers and engineers seeking to minimize the environmental impacts of their prototypes should share high-utilization machines, and are advised to use FDM machines over CNC mills or polyjet machines if they provide sufficient quality of surface finish. Originality/value – This is the first paper quantitatively comparing the environmental impacts of additive manufacturing with traditional machining. It also provides a more comprehensive measurement of environmental impacts than most studies of either milling or additive manufacturing alone – it includes not merely CO2 emissions or waste but also acidification, eutrophication, human toxicity, ecotoxicity and other impact categories. Designers, engineers and job shop managers may use the results to guide sourcing or purchasing decisions related to rapid prototyping.

scholarly journals Towards developing service quality index for zakat institutions

2017 ◽  
Vol 8 (3) ◽  
pp. 326-333 ◽  
Author(s):  
Norazlina Abd. Wahab ◽  
Zairy Zainol ◽  
Mahyuddin Abu Bakar
Keyword(s):  
Service Quality ◽  
Conceptual Model ◽  
Relevant Literature ◽  
Content Type ◽  
Distribution Of Wealth ◽  
Muslim Countries ◽  
The Poor ◽  
The Rich ◽  
The Needy

Purpose This paper aims to present a conceptual model on service quality of zakat institutions that are responsible for collecting, managing and distributing zakat in Malaysia. Zakat is an Islamic religious “tax” charged on the rich and well-to-do members of the community for distribution to the poor and the needy as well as other beneficiaries based on certain established criteria according to the Qur’an. The main aim of zakat is to protect the socio-economic welfare of the poor and the needy. Design/methodology/approach The paper reviews and synthesizes the relevant literature on service quality. The paper then proposed a conceptual model to study the service quality of zakat institutions. Findings The paper identifies the appropriate methods to examine the extent of service quality of zakat institutions. Such evaluations are crucial for organizations like zakat institutions to function effectively to achieve the noble objectives of socio-economic justice through proper distribution of wealth. Originality/value This paper presents a conceptual model of service quality of zakat institutions which would be useful for further empirical research in this area. The findings are not only relevant and applicable to Malaysia but also to other Muslim countries.

scholarly journals A bibliometric analysis of research in design for additive manufacturing

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Martins Ugonna Obi ◽  
Patrick Pradel ◽  
Matt Sinclair ◽  
Richard Bibb
Keyword(s):  
Additive Manufacturing ◽  
Bibliometric Analysis ◽  
Knowledge Development ◽  
Design For Additive Manufacturing ◽  
Global Knowledge ◽  
Content Type ◽  
Subject Areas ◽  
Manufacturing Knowledge ◽  
Bibliometric Approach

Purpose The purpose of this paper is to understand how Design for Additive manufacturing Knowledge has been developing and its significance to both academia and industry. Design/methodology/approach In this paper, the authors use a bibliometric approach to analyse publications from January 2010 to December 2020 to explore the subject areas, publication outlets, most active authors, geographical distribution of scholarly outputs, collaboration and co-citations at both institutional and geographical levels and outcomes from keywords analysis. Findings The findings reveal that most knowledge has been developed in DfAM methods, rules and guidelines. This may suggest that designers are trying to learn new ways of harnessing the freedom offered by AM. Furthermore, more knowledge is needed to understand how to tackle the inherent limitations of AM processes. Moreover, DfAM knowledge has thus far been developed mostly by authors in a small number of institutional and geographical clusters, potentially limiting diverse perspectives and synergies from international collaboration which are essential for global knowledge development, for improvement of the quality of DfAM research and for its wider dissemination. Originality/value A concise structure of DfAM knowledge areas upon which the bibliometric analysis was conducted has been developed. Furthermore, areas where research is concentrated and those that require further knowledge development are revealed.

Non-destructive quality control methods in additive manufacturing: a survey

2020 ◽  
Vol 26 (4) ◽  
pp. 777-790 ◽  
Author(s):  
Paschalis Charalampous ◽  
Ioannis Kostavelis ◽  
Dimitrios Tzovaras
Keyword(s):  
Quality Control ◽  
Additive Manufacturing ◽  
Complex Objects ◽  
Destructive Testing ◽  
Content Type ◽  
Wide Range ◽  
Manufacturing Procedure ◽  
Direct Energy ◽  
Non Destructive

Purpose In recent years, additive manufacturing (AM) technology has been acknowledged as an efficient method for producing geometrical complex objects with a wide range of applications. However, dimensional inaccuracies and presence of defects hinder the broad adaption of AM procedures. These factors arouse concerns regarding the quality of the products produced with AM and the utilization of quality control (QC) techniques constitutes a must to further support this emerging technology. This paper aims to assist researchers to obtain a clear sight of what are the trends and what has been inspected so far concerning non-destructive testing (NDT) QC methods in AM. Design/methodology/approach In this paper, a survey on research advances on non-destructive QC procedures used in AM technology has been conducted. The paper is organized as follows: Section 2 discusses the existing NDT methods applied for the examination of the feedstock material, i.e. incoming quality control (IQC). Section 3 outlines the inspection methods for in situ QC, while Section 4 presents the methods of NDT applied after the manufacturing process i.e. outgoing QC methods. In Section 5, statistical QC methods used in AM technologies are documented. Future trends and challenges are included in Section 6 and conclusions are drawn in Section 7. Findings The primary scope of the study is to present the available and reliable NDT methods applied in every AM technology and all stages of the process. Most of the developed techniques so far are concentrated mainly in the inspection of the manufactured part during and post the AM process, compared to prior to the procedure. Moreover, material extrusion, direct energy deposition and powder bed processes are the focal points of the research in NDT methods applied in AM. Originality/value This literature review paper is the first to collect the latest and the most compatible techniques to evaluate the quality of parts produced by the main AM processes prior, during and after the manufacturing procedure.

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