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Digital assembly and direct fabrication of mechanism based on selective laser melting Author(s): Xubin Su (School of Mechanical & Automotive Engineering, South China University of Technology, Guangzhou, China) ...Show all authors Abstract: Purpose – The purpose of this paper is to obtain more design freedom and realize fast fabrication of mechanism which is the core subsystem of many machines and always consists of several parts with assigned relative motion.

Design/methodology/approach – The mechanism is digitally assembled and later directly fabricated by selective laser melting (SLM) without post‐assembly. The joint is re‐designed to facilitate powdered material removal; the displays and the corresponding support additions are discussed to avoid too many supports within the clearances. Then, a series of universal joint are directly fabricated using SLM machine and a minimum clearance of 0.1 mm is obtained; a crank rocker mechanism is also fabricated and it can achieve the required performances. Findings – The digitally assembled mechanism can be successfully fabricated by SLM technique using metal powdered material. Originality/value – It is well known that the components fabricated by SLM have good mechanical properties. Therefore, it can be expected that more mechanisms with more design freedom will be developed and be used in some practical fields with improvement of fabrication quality. Keywords: Assembly, Advanced manufacturing technologies, Design, Mechanism, Direct fabrication, Selective laser melting, Digital assembly Type: Research paper Publisher: Emerald Group Publishing Limited Copyright: © Emerald Group Publishing Limited 2013 Published by Emerald Group Publishing Limited

Citation: Xubin Su, Yongqiang Yang, Di Wang, Yonghua Chen, (2013) "Digital assembly and direct fabrication of mechanism based on selective laser melting", Rapid Prototyping Journal, Vol. 19 Issue: 3, pp.166172, https://doi.org/10.1108/13552541311312157 Downloads: The fulltext of this document has been downloaded 896 times since 2013

Digital material fabrication using mask‐image‐projection‐based stereolithography Author(s): Chi Zhou (Daniel J. Epstein Department of Industrial and Systems Engineering, University of Southern California, Los Angeles, California, USA) ...Show all authors Abstract: Purpose – The purpose of this paper is to present a mask‐image‐projection‐based stereolithography (MIP‐SL) process that can combine two base materials with various concentrations and structures to produce a solid object with desired material characteristics. Stereolithography is an additive manufacturing process in which liquid photopolymer resin is cross‐linked and converted to solid. The fabrication of digital material requires frequent resin changes during the building process. The process presented in this paper attempts to address the related challenges in achieving such fabrication capability.

Design/methodology/approach – A two‐channel system design is presented for the multi‐material MIP‐SL process. In such a design, a coated thick film and linear motions in two axes are used to reduce the separation force of a cured layer. The material cleaning approach to thoroughly remove resin residue on built surfaces is presented for the developed process. Based on a developed testbed, experimental studies were conducted to verify the effectiveness of the presented process on digital material fabrication. Findings – The proposed two‐channel system can reduce the separation force of a cured layer by an order of magnitude in the bottom‐up projection system. The developed two‐stage cleaning approach can effectively remove resin residue on built surfaces. Several multi‐material designs have been fabricated to highlight the capability of the developed MIP‐SL process. Research limitations/implications – A proof‐of‐concept testbed has been developed. Its building speed and accuracy can be further improved. The tests were limited to the same type of liquid resins. In addition, the removal of trapped air is a challenge in the presented process.

Originality/value – This paper presents a novel and a pioneering approach towards digital material fabrication based on the stereolithography process. This research contributes to the additive manufacturing development by significantly expanding the selection of base materials in fabricating solid objects with desired material characteristics. Keywords: Advanced manufacturing technologies, Polymers, Resins, Additive manufacturing, Multi‐material fabrication, Stereolithography, Digital material Type: Research paper Publisher: Emerald Group Publishing Limited Copyright: © Emerald Group Publishing Limited 2013 Published by Emerald Group Publishing Limited Citation: Chi Zhou, Yong Chen, Zhigang Yang, Behrokh Khoshnevis, (2013) "Digital material fabrication using mask‐image‐projection‐based stereolithography", Rapid Prototyping Journal, Vol. 19 Issue: 3, pp.153165, https://doi.org/10.1108/13552541311312148 Downloads: The fulltext of this document has been downloaded 2456 times since 2013

Comparison of different post processing technologies for SLM generated 316l steel parts Author(s): Lukas Löber (Institute for Materials Science, University of Technology, Dresden, Germany) ...Show all authors Acknowledgements: The authors thank Dr Klemm and Dr Hoffmann for the stimulating discussions about this work. This work has been supported by the European Union and the Free State of Saxonia in the framework of the European Centre for Emerging Materials and Processes, International Graduate School (ECEMP IGS), contract no. 13795/2379. Abstract: Purpose

– The purpose of this paper is to compare different post processing techniques for improving the high surface roughness (SR) characteristic of parts generated by selected laser melting (SLM).

Design/methodology/approach – Test parts were built by SLM and their surface was characterized via SEM and optical measurements. The surface of the as‐generated parts was then modified by grinding, sand blasting and electrolytic and plasma polishing to reduce the SR. Findings – The change of the SR after the different surface treatments was quantified and compared. The effectiveness and usability of the post processing techniques and their combinations were determined. The results indicate that some of the post processes are only usable for simple structures. Research limitations/implications – The amount of abrasion induced by the different surface treatments was not quantified. A major focus of future work should deal with this issue. Practical implications – The surface quality of parts with simple geometry can be enhanced by simple methods such as grinding. Complex parts need more advanced techniques, such as electrolytic polishing. Originality/value – The effect of different post processing techniques for improving the surface roughness of SLM‐generated parts has been analyzed for the first time. This paper can help to improve the SR of parts produced by SLM. Keywords: Surface properties of materials, Steel, Surface roughness measurement, Selective laser melting Type: Research paper Publisher: Emerald Group Publishing Limited Copyright: © Emerald Group Publishing Limited 2013 Published by Emerald Group Publishing Limited Citation: Lukas Löber, Christoph Flache, Romy Petters, Uta Kühn, Jürgen Eckert, (2013) "Comparison of different post processing technologies for SLM generated 316l steel parts", Rapid Prototyping Journal, Vol. 19 Issue: 3, pp.173179, https://doi.org/10.1108/13552541311312166 Downloads: The fulltext of this document has been downloaded 2105 times since 2013 1.

The investigation of the influence of laser re‐melting on density, surface quality and microstructure of selective laser melting parts

Evren Yasa et al., Rapid Prototyping Journal, 2013 2.

Accuracy and density optimization in directly fabricating customized orthodontic production by selective laser melting Yongqiang Yang et al., Rapid Prototyping Journal, 2013

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Selective laser melting of biocompatible metals for rapid manufacturing of medical parts Ben Vandenbroucke et al., Rapid Prototyping Journal, 2013

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Influence of the particle size distribution on surface quality and mechanical properties in AM steel parts A.B. Spierings et al., Rapid Prototyping Journal, 2013

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Effect of preheat and layer thickness on selective laser melting (SLM) of magnesium Monica Mahesh Savalani et al., Rapid Prototyping Journal, 2016 1.

Electrons dynamics control by shaping femtosecond laser pulses in micro/nanofabrication: modeling, method, measurement and application Lan Jiang et al., Light: Science & Applications, 2018

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Plasmonic nano-printing: large-area nanoscale energy deposition for efficient surface texturing Lei Wang et al., Light: Science & Applications, 2017

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Design and Fabrication of Metal Microcup Mould for E-Paper PU Dong-lin1 et al., Chinese Journal of Liquid Crystals and Displays

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Ablative Laser Resurfacing - Postoperative Care R.S. Batra et al., Medscape

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Investigation on the laser ablation of SiC ceramics using micro-Raman mapping technique Chaoli FU et al., Journal of Advanced Ceramics, 2016

Development of CNTs-filled photopolymer for projection stereolithography Author(s): Hengky Eng , (Singapore Institute of Manufacturing Technology, Singapore, Singapore) ...Show all authors Single Sentence Summary: The development of carbon nanotubes (CNTs)-filled photopolymer for projection stereolithography reveals that with the addition of 0.25 wt.% CNTs into the

photopolymer, tensile stress and elongation of the 3D printed parts increase by 70 and 46 per cent, respectively. Abstract: Purpose Polymeric parts produced by 3D stereolithography (SL) process have poorer mechanical properties as compared to their counterparts fabricated via conventional methods, such as injection or compression molding. Adding nanofillers in the photopolymer resin for SL could help improve mechanical properties. This study aims to achieve enhancement in mechanical properties of parts fabricated by SL, for functional applications, by using well-dispersed nanofillers in the photopolymers, together with suitable post-processing.

Design/methodology/approach Carbon nanotubes (CNTs) have high strength and Young’s modulus, making them attractive nanofillers. However, dispersion of CNTs in photopolymer is a critical challenge, as they tend to agglomerate easily. Achieving good dispersion is crucial to improve the mechanical properties; thus, suitable dispersion mechanisms and processes are examined. Solvent exchange process was found to improve the dispersion of multiwalled carbon nanotubes in the photopolymer. The UV-absorbing nature of CNTs was also discovered to affect the curing properties. With suitable post processing, coupled with thermal curing, the mechanical properties of SL parts made from CNTs-filled resin improved significantly. Findings With the addition of 0.25 wt.% CNTs into the photopolymer, tensile stress and elongation of the 3D printed parts increased by 70 and 46 per cent, respectively. With the significant improvement, the achieved tensile strength is comparable to parts manufactured by conventional methods. Practical implications This allows functional parts to be manufactured using SL. Originality/value In this paper, an improved procedure to incorporate CNTs into the photopolymer was developed. Furthermore, because of strong UV-absorption nature of CNTs, curing properties of photopolymer and SL parts with and without CNT fillers were studied. Optimized curing parameters were determined and additional postprocessing step for thermal curing was discovered as an essential step in order to further enhance the mechanical properties of SL composite parts. Keywords: Resins, Composites, Mechanical properties, Stereolithography, UV, Thermal postcure Type: Research Paper Publisher: Emerald Publishing Limited Received: 21 October 2015 Revised:

18 January 2016 Accepted: 09 March 2016 Copyright: © Emerald Publishing Limited 2017 Published by Emerald Publishing Limited Licensed re-use rights only Citation: Hengky Eng, Saeed Maleksaeedi, Suzhu Yu, Yu Ying Clarrisa Choong, Florencia Edith Wiria, Ruihua Eugene Kheng, Jun Wei, Pei-Chen Su, Huijun Phoebe Tham, (2017) "Development of CNTs-filled photopolymer for projection stereolithography", Rapid Prototyping Journal, Vol. 23 Issue: 1, pp.129136, https://doi.org/10.1108/RPJ-10-2015-0148 Downloads: The fulltext of this document has been downloaded 412 times since 2017

Abrasive flow finishing of stereolithography prototypes Author(s): Robert E. Williams (Assistant Professor, Department of Industrial and Management Systems Engineering and the Center for Nontraditional Manufacturing Research at the University of Nebraska‐Lincoln, Nebraska, USA) ...Show all authors Acknowledgements: The authors would like to thank the National Science Foundation (Faculty CAREER Grant No. DMI‐9701941) and Extrude Hone Corporation for their support of this research. This material is also based on work supported by, or in part by, the US Army Research Office under contract/grant number DAAH04‐94‐G‐0339. 3D Systems deserves recognition for providing the SL5180 prototypes. Finally, the authors recognize the help of Eric Clark in preparing this manuscript. Abstract: This research investigated the use of two relatively new technologies, abrasive flow machining (AFM) and stereolithography (SL), to minimize the time to develop a finished prototype. Statistical analysis was used to determine effects of media grit size, media pressure, build style, build orientation and resin type on flatness, material removal rate and surface roughness. Results indicated that media pressure, grit size, and build orientation were significant in at least one of the experiments performed. Scanning electron microscope (SEM) images showed the stair‐stepping effect of the SL process before AFM and the removal of the stair‐stepping after AFM. The SEM images showed a lack of typical AFM flowlines on the surface and suggested that the workpiece material is removed by brittle fracture. Data dependent systems analysis techniques were also used to study the surface roughness profiles.

Keywords: Machining, Prototyping, Surface finishing Type: Research paper Publisher: MCB UP Ltd Copyright: © MCB UP Limited 1998 Published by MCB UP Ltd Citation: Robert E. Williams, Vicki L. Melton, (1998) "Abrasive flow finishing of stereolithography prototypes", Rapid Prototyping Journal, Vol. 4 Issue: 2, pp.5667, https://doi.org/10.1108/13552549810207279 Downloads: The fulltext of this document has been downloaded 986 times since 2013

Influence of layer thickness on mechanical properties in stereolithography Author(s): K. Chockalingam (Thiagarajar College of Engineering, Madurai, India) ...Show all authors Acknowledgements: The authors thank the Management, Principal and the Head of the Department of Mechanical Engineering of Thiagarajar College of Engineering, Madurai, for their co‐operation and encouragement. The authors also thank the Management of M/s Gas Turbine Research Establishment, Bangalore for the permission to carry out the experiments. The authors also thank the anonymous referees for their valuable suggestions. Abstract: Purpose – Mechanical properties such as tensile, yield, impact strengths, and development of residual stresses play an important role intooling applications. The objective of this paper is to investigate the effect of layer thickness – one of the influential process parameters in stereolithography (SL) process, on mechanical properties of SL components.

Design/methodology/approach – Test specimens are constructed as per the ASTM standards for different layer thicknesses in SL 5000 machine, using epoxy resin CIBA tool ® SL5530, a high temperature resistant SL material that is suitable for rapid tooling applications.

Tensile, yield and impact tests are carried out with suitable equipments. Residual stress is analysed using hole drill method.

Findings – The analysis reveals that when the layer thickness is smaller, the strength of the part is higher. Research limitations/implications – Conclusion of this research is drawn based on the analysis of the most widely used three layer thicknesses of 100, 125 and 150 μm. X‐ray diffraction or molecular resonance analysis may be useful to understand the reason for the variation in mechanical properties. Originality/value – This experimental study provides the useful information to the SL machine users in the selection of layer thickness to manufacture rapid tools. Keywords: Process efficiency, Mechanical properties of materials Type: Research paper Publisher: Emerald Group Publishing Limited Copyright: © Emerald Group Publishing Limited 2006 Published by Emerald Group Publishing Limited Citation: K. Chockalingam, N. Jawahar, U. Chandrasekhar, (2006) "Influence of layer thickness on mechanical properties in stereolithography", Rapid Prototyping Journal, Vol. 12 Issue: 2, pp.106113, https://doi.org/10.1108/13552540610652456 Downloads: The fulltext of this document has been downloaded 2731 times since 2013

Influence of layer thickness on mechanical properties in stereolithography Author(s): K. Chockalingam (Thiagarajar College of Engineering, Madurai, India) ...Show all authors Acknowledgements: The authors thank the Management, Principal and the Head of the Department of Mechanical Engineering of Thiagarajar College of Engineering, Madurai, for their

co‐operation and encouragement. The authors also thank the Management of M/s Gas Turbine Research Establishment, Bangalore for the permission to carry out the experiments. The authors also thank the anonymous referees for their valuable suggestions. Abstract: Purpose – Mechanical properties such as tensile, yield, impact strengths, and development of residual stresses play an important role intooling applications. The objective of this paper is to investigate the effect of layer thickness – one of the influential process parameters in stereolithography (SL) process, on mechanical properties of SL components.

Design/methodology/approach – Test specimens are constructed as per the ASTM standards for different layer thicknesses in SL 5000 machine, using epoxy resin CIBA tool ® SL5530, a high temperature resistant SL material that is suitable for rapid tooling applications. Tensile, yield and impact tests are carried out with suitable equipments. Residual stress is analysed using hole drill method. Findings – The analysis reveals that when the layer thickness is smaller, the strength of the part is higher. Research limitations/implications – Conclusion of this research is drawn based on the analysis of the most widely used three layer thicknesses of 100, 125 and 150 μm. X‐ray diffraction or molecular resonance analysis may be useful to understand the reason for the variation in mechanical properties. Originality/value – This experimental study provides the useful information to the SL machine users in the selection of layer thickness to manufacture rapid tools. Keywords: Process efficiency, Mechanical properties of materials Type: Research paper Publisher: Emerald Group Publishing Limited Copyright: © Emerald Group Publishing Limited 2006 Published by Emerald Group Publishing Limited Citation: K. Chockalingam, N. Jawahar, U. Chandrasekhar, (2006) "Influence of layer thickness on mechanical properties in stereolithography", Rapid Prototyping Journal, Vol. 12 Issue: 2, pp.106113, https://doi.org/10.1108/13552540610652456 Downloads:

The fulltext of this document has been downloaded 2731 times since 2013

Modeling effects of oxygen inhibition in mask‐based stereolithography Author(s): Amit S. Jariwala (George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA) Fei Ding (George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA) Aparna Boddapati (School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA) Victor Breedveld (School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA) Martha A. Grover (School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA) Clifford L. Henderson (School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA) David W. Rosen (George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA) Abstract: Purpose – The purpose of this paper is to present a model that can be used to simulate the photopolymerization process in micro‐stereolithography (SL) in order to predict the shape of the cured parts. SL is an additive manufacturing process in which liquid photopolymer resin is cross‐linked and converted to solid with a UV laser light source. Traditional models of SL processes do not consider the complex chemical reactions and species transport occurring during photopolymerization and, hence, are incapable of accurately predicting resin curing behavior. The model presented in this paper attempts to bridge this knowledge gap.

Design/methodology/approach – The chemical reactions involved in the photopolymerization of acrylate‐based monomers were modeled as ordinary differential equations (ODE). This model incorporated the effect of oxygen inhibition and diffusion on the polymerization reaction. The model was simulated in COMSOL and verified with experiments conducted on a mask‐based micro‐SL system. Parametric studies were conducted to investigate the possibilities to improve the accuracy of the model for predicting the edge curvature. Findings – The proposed model predicts well the effect of oxygen inhibition and diffusion on photopolymerization, and the model accurately predicts the cured part height when compared to experiments conducted on a mask‐based SL system. The simulated results also show the characteristic edge curvature as seen in experiments.

Research limitations/implications – A triacrylate monomer was used in the experiments conducted, so results may be limited to acrylate monomers. Shrinkage was not considered when comparing cured part shapes to those predicted using COMSOL. Originality/value – This paper presents a unique and a pioneering approach towards modeling of the photopolymerization reaction in micro‐SL process. This research furthers the development of patent pending film micro‐SL process which can be used for fabrication of custom micro‐optical components. Keywords: Polymerization, Modelling, Oxygen, Chemical kinetics Type: Research paper Publisher: Emerald Group Publishing Limited Copyright: © Emerald Group Publishing Limited 2011 Published by Emerald Group Publishing Limited Citation: Amit S. Jariwala, Fei Ding, Aparna Boddapati, Victor Breedveld, Martha A. Grover, Clifford L. Henderson, David W. Rosen, (2011) "Modeling effects of oxygen inhibition in mask‐based stereolithography", Rapid Prototyping Journal, Vol. 17 Issue: 3, pp.168-175, https://doi.org/10.1108/13552541111124734 Downloads: The fulltext of this document has been downloaded 837 times since 2013