Emerald | Rapid Prototyping Journal | Table of Contents http://www.emeraldinsight.com/1355-2546.htm Table of contents from the most recently published issue of Rapid Prototyping Journal Journal en-gb Tue, 12 Aug 2014 00:00:00 +0100 2013 Emerald Group Publishing Limited editorial@emeraldinsight.com support@emeraldinsight.com 60 Emerald | Rapid Prototyping Journal | Table of Contents http://www.emeraldinsight.com/common_assets/img/covers_journal/rpjcover.gif http://www.emeraldinsight.com/1355-2546.htm 120 157 Editorial http://www.emeraldinsight.com/journals.htm?issn=1355-2546&volume=20&issue=5&articleid=17116009&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - Editorial<B>Design/methodology/approach</B> - Editorial<B>Findings</B> - Editorial<B>Originality/value</B> - Editorial Article literatinetwork@emeraldinsight.com (R. Ian Campbell) Tue, 12 Aug 2014 00:00:00 +0100 Microstructure study on selective laser melting yttria stabilized zirconia ceramic with near IR fiber laser http://www.emeraldinsight.com/journals.htm?issn=1355-2546&volume=20&issue=5&articleid=17116020&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - This paper explores selective laser melting of yttria stabilized zirconia ceramic by a 1µm wavelength fiber laser, and investigates the influence of different laser powers and different scanning velocities on the microstructure, the relative density, the deformation of ceramic sample, the micro-hardness, and it analyses the crystal structure transformation during the fabrication. <B>Design/methodology/approach</B> - During the fabrication, the 5mm×5mm×5mm YSZ ceramic samples are fabricated by RP machine MCP realizer SLM 250, density and microscopic photographs shows the ceramic melting situation. The density of cubic sample with different laser power and different scanning velocities is measured by Archimedes method, The microstructure of samples and powder is observed by SEM. The micro-hardness is measured by the Vickers microhardness equipment, and the crystal structure transition is research by XRD.<B>Findings</B> - It’s possible to melt YSZ powder completely with near IR fiber laser, and the relative density of 5mm×5mm×5mm cubic sample is 88%, the micro-hardness could reach 1209±262HV500. And the influence of laser power on the volume deformation is more sensitive than the scanning speed at the same energy density. The small pores and the obvious orderly cracks can be observed in the cross section of sample, the uneven distribution of laser energy input is the main reason of the formation of orderly cracks. The transformation from monoclinic and cubic crystal to tetragonal crystal occurred during the melting process. Heat treatment (1400?-30min) cannot significantly improve the density of the sample, but it can restore the color of ceramic.<B>Research limitations/implications</B> - Particularly serious due to the deformation of the ceramic material, so we can not prepare a large ceramic samples and measure its macroscopic mechanical properties.<B>Originality/value</B> - This paper manufactures YSZ ceramic sample by sls technology with a 1µm wavelength fiber laser, and preliminary studies the microscopic structure, distribution of laser parameters and crystal transformation. Article literatinetwork@emeraldinsight.com (Qi LIU, Bo SONG, Hanlin LIAO) Tue, 12 Aug 2014 00:00:00 +0100 Cyber-enabled Manufacturing Systems for Additive Manufacturing http://www.emeraldinsight.com/journals.htm?issn=1355-2546&volume=20&issue=5&articleid=17116030&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The technology of additive manufacturing (AM) or solid freeform fabrication has received considerable attention in recent years. Several public and private interests are exploring AM to find solutions to manufacturing problems and to create new opportunities. For AM to be commercially accepted, it must make products reliably and predictably. AM processes must achieve consistency and be reproducible. <B>Design/methodology/approach</B> - An approach we have taken is to foster a basic research program in cyber-enabled manufacturing systems (CeMS) for additive manufacturing. The long-range goal of the program is to achieve the level of control over AM processes for industrial acceptance and wide-use of the technology. This program will develop measurement, sensing, manipulation and process control models and algorithms for AM by harnessing principles underpinning cyber-physical systems (CPS) and fundamentals of physical processes. <B>Findings</B> - This paper describes the challenges facing AM and the CeMS program goals to meet them. It also presents preliminary results of studies in thermal modeling and process models.<B>Originality/value</B> - The development of CeMS concepts for additive manufacturing should address issues such as part quality and process dependability, which are key for successful application of this disruptive rapid manufacturing technology. Article literatinetwork@emeraldinsight.com (Khershed P. Cooper, Ralph F. Wachter) Tue, 12 Aug 2014 00:00:00 +0100 Tensile Strength of Functionally Graded and Wafer Layered Structures produced by Direct Metal Deposition http://www.emeraldinsight.com/journals.htm?issn=1355-2546&volume=20&issue=5&articleid=17116064&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - This paper aims to investigate the changes in tensile properties of novel functionally graded materials and wafer structures created by Direct Metal Deposition (DMD) additive manufacturing technology.<B>Design/methodology/approach</B> - Laser assisted direct metal deposition was used to create two innovative sets of metallic structures - the functionally graded and wafer layered structures - using pairs of six different engineering alloys in different combinations. These alloys were selected due to their high popularity within a diverse range of industries and engineering applications. The laser assisted DMD was selected as a suitable technique to create these complex structures because of its capability to deposit more than one alloy powder at a time. After creation of these structures, their tensile strength was tested in a series of tensile tests and the results were compared with those of single alloy samples.<B>Findings</B> - It was observed that the mechanical properties of FGM and wafer structure samples were clearly different from those of the single alloy samples, a fact which creates a whole pool of opportunities to development of new materials or structures with desired mechanical properties that cannot be achieved in single alloy parts. <B>Originality/value</B> - The study demonstrates the application of the DMD process to produce unique structures and materials, which would be high in demand in engineering applications, where metallic parts are exposed to high loads and excessive tensile stresses may adversely affect the performance of such parts. Article literatinetwork@emeraldinsight.com (Mehdi Soodi, Syed Hasan Masood, Milan Brandt) Tue, 12 Aug 2014 00:00:00 +0100 Inhibition of phase transformation from ß- to a-tricalcium phosphate with addition of Poly (L-lactic acid) in selective laser sintering http://www.emeraldinsight.com/journals.htm?issn=1355-2546&volume=20&issue=5&articleid=17116069&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The paper aims to fabricate a TCP scaffold with an interconnected porous structure via selective laser sintering (SLS). To inhibit the phase transformation from ß- to a-TCP in fabrication process of porous scaffolds, a small amount (1 wt%) of poly (L-lactic acid) (PLLA) is added into ß-TCP powder to introduce the transient liquid phase.<B>Design/methodology/approach</B> - The paper opted for the transient liquid phase of melting PLLA to decrease the sintering temperature in SLS. Meanwhile, the densification of ß-TCP is enhanced with a combined effect of the capillary force caused by melting PLLA and the surface energy of ß-TCP particles. Moreover, the PLLA will gradually decompose and completely disappear with laser irradiation.<B>Findings</B> - The testing results show the addition of PLLA enables the scaffolds to achieve a higher ß-TCP content of 77±1.49 wt% compared with the scaffold sintered from ß-TCP powder (60±1.65 wt%), when the laser energy density is 0.4 J/mm2. The paper provides the mechanism of PLLA inhibition on the phase transformation from ß- to a-TCP. And the optimum sintering parameters are obtained based on experimental results, which are used to prepare a TCP scaffold with interconnected porous structure via SLS.<B>Research limitations/implications</B> - This paper shows that the laser energy density is an important sintering parameter that can provide the means to control the micro-porous structure of the scaffold. If the laser energy density is too low, the densification is not enough. On the other hand, If the laser energy density is too high, the microcracks are observed which are attributed to the volume expansion during the phase transformation from ß- to a-TCP. So, the laser energy density must be optimized.<B>Originality/value</B> - The paper provides a feasible method for fabricating TCP artificial bone scaffold with good biological and mechanical properties. Article literatinetwork@emeraldinsight.com (Cijun Shuai, Jingyu Zhuang, Shuping Peng, Xuejun Wen) Tue, 12 Aug 2014 00:00:00 +0100 An integrated decision making model for Multi-Attributes Decision Making (MADM) problems in Additive Manufacturing process planning http://www.emeraldinsight.com/journals.htm?issn=1355-2546&volume=20&issue=5&articleid=17116027&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The purpose of this paper is to propose an integrated decision making model for Multi-Attributes Decision Making (MADM) problems in Additive Manufacturing process planning, as well as for related MADM problems in other research areas.<B>Design/methodology/approach</B> - This research analyzed the drawbacks of former methods and then proposed two sub decision making models, ‘deviation model’ and ‘similarity model’. The former sub model aimed to measure the deviation extent of each alternative to the aspired goal based on analyzing Euclidean distance between them. While the latter sub model applying Grey Incidence analysis was used to measure the similarity between alternatives and the expected goal by investigating the curve shape of each alternative. Afterwards, an integrated model based on the aggregation of the two sub models was proposed and verified by numerical example and simple case studies.<B>Findings</B> - The calculating results of the cited numerical example and the comparison to former related research showed that this proposed model is more practical and reasonable than former methods applied in MADM problems of AM. In addition, the proposed model can be also applied in other fields where exists MADM problems.<B>Originality/value</B> - This proposed integrated model not only considers the deviation extent of alternatives to the aspired goal, but also investigated the similarity between alternatives and the expected goal. The similarity analysis compensates the drawbacks of traditional ‘distance-based’ models or methods that can’t distinguish alternatives which have the same distance-based index value. Article literatinetwork@emeraldinsight.com (Yicha ZHANG, Alain Bernard) Tue, 12 Aug 2014 00:00:00 +0100 A Method to Represent Heterogeneous Materials for Rapid Prototyping – The Matryoshka Approach http://www.emeraldinsight.com/journals.htm?issn=1355-2546&volume=20&issue=5&articleid=17116034&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The purpose of this paper is to present a new method for representing heterogeneous materials using nested STL shells, based in particular on the density distributions of human bones.<B>Design/methodology/approach</B> - Nested STL shells, called Matryoshka models, are described based upon their namesake Russian nesting dolls. In this approach polygonal models, such as STL shells, are "stacked" inside one another to represent different material regions. The Matryoshka model addresses the challenge of representing different densities and different types of bone when reverse engineering from medical images. The Matryoshka model is generated via an iterative process of thresholding the Hounsfield Unit (HU) data from a computed tomography (CT) scan, thereby delineating regions of progressively increasing bone density. These nested shells can represent regions starting with the medullary (bone marrow) canal, up through and including the outer surface of the bone.<B>Findings</B> - The Matryoshka approach introduced can be used to generate accurate models of heterogeneous materials in an automated fashion, avoiding the challenge of hand-creating an assembly model for input to multi-material additive or subtractive manufacturing.<B>Originality/value</B> - This paper presents a new method for describing heterogeneous materials: in this case, the density distribution in a human bone. The authors show how the Matryoshka model can be used to plan harvesting locations for creating custom rapid allograft bone implants from donor bone. An implementation of a proposed harvesting method is demonstrated, followed by a case study using Subtractive Rapid Prototyping to harvest a bone implant from a human tibia surrogate. Article literatinetwork@emeraldinsight.com (Shuangyan Lei, Matthew Charles Frank, Donald D. Anderson, Thomas D. Brown) Tue, 12 Aug 2014 00:00:00 +0100 Options for additive rapid prototyping methods (3D printing) in MEMS technology. http://www.emeraldinsight.com/journals.htm?issn=1355-2546&volume=20&issue=5&articleid=17116050&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - Additive rapid prototyping technologies such as stereolithography (SLA), fused deposition modeling (FDM) and selective laser sintering (SLS), all commonly known as 3D printing methods, are reviewed and compared with the resolution requirements of the traditional MEMS fabrication methods. <B>Design/methodology/approach</B> - In the 3D print approach, the entire assembly, parts and prototypes are built using various plastic and metal materials directly from the software file input, completely bypassing any additional processing steps. The review highlights their potential place in the overall process flow to reduce the complexity of traditional microfabrication and long processing cycles needed to test multiple prototypes before the final design is set. <B>Findings</B> - Additive manufacturing is a promising manufacturing technique in micro-device technology. <B>Practical implications</B> - In the current state of 3D printing, microfluidic and lab-on-a-chip devices for fluid handling and manipulation appear to be the most compatible with the 3D print methods, given their fairly coarse minimum feature size of 50-500 ?m. Future directions in the 3D materials and method development are identified, such as adhesion and materials compatibility studies of the 3D print materials, wafer-level printing, conductive materials development and others. One of the most important goals should be the drive towards finer resolution and layer thickness (1-10 ?m) to stimulate the use of the 3D printing in a wider array of MEMS devices. <B>Originality/value</B> - The review combines two discrete disciplines, microfabrication and additive manufacturing (AM), and shows how microfabrication and micro-device commercialization may benefit from employing methods developed by the AM community. Article literatinetwork@emeraldinsight.com (Victor Lifton, Gregory Lifton, Steve Simon) Tue, 12 Aug 2014 00:00:00 +0100 Characterization of Sintered Hydroxyapatite samples produced by 3D printing http://www.emeraldinsight.com/journals.htm?issn=1355-2546&volume=20&issue=5&articleid=17116071&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - This study is part of a project concerned with the fabrication of calcium phosphates implants by 3D printing. However, before considering a more complex structure, like scaffolds or implants, a thorough knowledge of the role played by the sintering temperature on physical and mechanical the properties of porous hydroxyapatite (HA) is necessary.<B>Design/methodology/approach</B> - The characteristics of sintered HA samples have be analyzed by means of x-ray diffraction, SEM and uniaxial compression tests. The 3D printing parameters used to produce the HA samples were those who led to higher accuracy and mechanical stability. <B>Findings</B> - Sintering temperature and powder morphology are critical factors influencing densification behavior, porosity, phase stability, mechanical strength and tangent modulus of the HA samples produced by 3D printing. This study allowed to conclude about the 3D printing parameters to be use to produce porous hydroxyapatite specimens with the required integrity and dimensional accuracy, and the optimal post-processing sintering temperature which led to the best results in terms of porosity, microstructure, phase stability of HA and mechanical properties. <B>Originality/value</B> - This paper provides a method to evaluate the manufacturability of calcium phosphate models produced by 3D printing. Article literatinetwork@emeraldinsight.com (Inês Pires, Bárbara Gouveia, Jorge Rodrigues, Ruben Fonte) Tue, 12 Aug 2014 00:00:00 +0100 Conversion of a GIS surface data directly to a 3D STL part for terrain modelling http://www.emeraldinsight.com/journals.htm?issn=1355-2546&volume=20&issue=5&articleid=17116021&show=abstract <strong>Abstract</strong><br /><br /><B>Purpose</B> - The GIS data available for a terrain is the data of its surface. It doesn’t have information for a solid model. The data needs to be converted into a 3D solid model for making physical models by Additive Manufacturing (AM). This work aims to convert surface data directly to a 3D STL part. <B>Design/methodology/approach</B> - A methodology has been developed to make the wall and base of the part and tessellates the part with triangles. A program has been written which gives output of the part in STL (STereoLithography) file format. The elevation data is interpolated and any singularity present is removed. Extensive search techniques are used.<B>Findings</B> - AM technologies are increasingly being used for terrain modelling. However, there is not enough work done to convert the surface data into 3D solid model. The present work aids in this area.<B>Practical implications</B> - The methodology removes data loss associated with intermediate file formats. Terrain models can be created in less time and less cost. Intricate geometries of terrain can be created with ease and great accuracy.<B>Originality/value</B> - The work allows direct and automated conversion of GIS surface data into a 3D STL part. It removes intermediate steps and any data loss associated with intermediate file formats. Article literatinetwork@emeraldinsight.com (Sanat Agrawal, Deon John de Beer, Yashwant Kumar Modi) Tue, 12 Aug 2014 00:00:00 +0100