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Article
Publication date: 1 December 2000

Jeng‐Ywan Jeng, Jia‐Chang Wang and Tsung Te Lin

The key principle of the jet deposition rapid prototyping (RP) system is to deliver material through a jet and deposit the liquefied material onto a platform to build a…

Abstract

The key principle of the jet deposition rapid prototyping (RP) system is to deliver material through a jet and deposit the liquefied material onto a platform to build a physical model. Model Maker (MM) RP system is one of the jet deposition processes with the smallest slice thickness and better model accuracy. In order to maintain thinner layer thickness and model accuracy, a cutter is employed to plane off the deposited surface. The fabrication speed for MM models is extremely low because of the employment of the tiny jet and the cutting operation. The model interior filling does not affect the model accuracy very much but it does significantly affect the fabrication speed. Hence, a new flexible layer fabrication method is proposed in this paper to separate the fabrication processes of the profile and the interior, respectively, in order to maintain model accuracy and thinner slice thickness, and to accelerate the fabrication speed.

Details

Rapid Prototyping Journal, vol. 6 no. 4
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 May 2009

Yu‐Shan Chen and Bi‐Yu Chen

The purpose of this paper is to use data envelopment analysis (DEA) to evaluate the efficiency of the wafer fabrication industry in Taiwan.

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1093

Abstract

Purpose

The purpose of this paper is to use data envelopment analysis (DEA) to evaluate the efficiency of the wafer fabrication industry in Taiwan.

Design/methodology/approach

The input variables are total assets, operation costs, and operation expenditures, and the output variable is net sales. This study uses the Pearson correlation to indicate positively correlation between input and output variables, applies DEA to analyze the efficiency scores, and utilizes Mann‐Whitney U‐test to compare the efficiency score of stock exchange market group (SEM group) with that of over‐the‐counter market group (OTC group). Moreover, this paper explores the efficiency performance over different periods by use of the Malmquist productive Index (MPI).

Findings

This study indicates that Taiwan Semiconductor Manufacturing Corporation (TSMC) has the most relative efficiency in the wafer fabrication industry of Taiwan. In addition, this study finds out the average constant returns to scale (CRS) efficiency of the Taiwanese wafer fabrication industry from 1999 to 2003 is 84.98 per cent, and the average CRS efficiencies of all nine wafer fabrication companies are over 70 per cent. This study finds out that net sales and scale efficiency of SEM group are higher than those of OTC group. Moreover, this study shows that the main inefficient causes of four companies of SEM group except TSMC and Nanya are from the inefficiency of variable returns to scale efficiency, while the main inefficient causes of all companies of OTC group are from the inefficiency of scale efficiency. Finally, according the results of the MPI in this study, the wafer fabrication industry should introduce the new technology to improve its technology change effect.

Originality/value

This study provides a valuable reference for wafer fabrication companies not only in reviewing their efficiency, but also in enhancing their operational performance.

Details

Journal of Manufacturing Technology Management, vol. 20 no. 4
Type: Research Article
ISSN: 1741-038X

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Article
Publication date: 16 January 2009

Gul Polat

The purpose of this paper is to assess the impacts of implementing different combinations of various organizational changes on the economics of rebar supply chains in the…

Abstract

Purpose

The purpose of this paper is to assess the impacts of implementing different combinations of various organizational changes on the economics of rebar supply chains in the special conditions of a project environment, where on‐site fabrication of rebar is considered to be more economical than off‐site fabrication practice.

Design/methodology/approach

A range of recently published works (2005‐2006) seem to confirm that on‐site fabrication of rebar results in less cost to the contractor compared with off‐site fabrication in a special project environment. However, those analyses did not take into account two main cost components (i.e. storage cost and waiting cost) owing to the lack of such information, and they were based on a number of assumptions regarding current managerial capabilities, which may likely be enhanced through implementing various organizational changes. This study overcame these shortcomings of the recent studies through restoring the formerly developed simulation model to mimic the materials management system actually used by a contractor, and running this system by plugging in realistic input values associated with both those cost components and organizational changes.

Findings

The paper reveals that while fabricating rebar off site is more economical than fabricating it on site when the storage and waiting costs were taken into account in the current state of the construction industry, and the lowest total cost of rebar can be achieved by implementing organizational changes in the on‐site fabrication practice.

Originality/value

This paper is a very useful source of information for practitioners and researchers because it indicates that off‐site fabrication practice is only beneficial to builders if they have the ability to exploit it, and if the cultural and business environment enables that exploitation.

Details

Construction Innovation, vol. 9 no. 1
Type: Research Article
ISSN: 1471-4175

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Article
Publication date: 1 December 2004

Wei Sun, Tao Jiang and Feng Lin

A processing algorithm for freeform fabrication of heterogeneous structures is presented. The algorithm was developed based on the heterogeneous fabrication structural…

Abstract

A processing algorithm for freeform fabrication of heterogeneous structures is presented. The algorithm was developed based on the heterogeneous fabrication structural model, which was constructed from the STL based multi‐material volume regions and with material identifications. The reasoning Boolean operation based modelling approach was used to construct the heterogeneous CAD assembly and to output the needed STL format. Procedures for generating the database hierarchy and the storage of the heterogeneous structural model, and derivation for developing the processing algorithm for layered fabrication of heterogeneous structure are presented. The developed algorithm was applied to a heterogeneous structure consisting of two discrete material volumes, and the detailed processing path is described.

Details

Rapid Prototyping Journal, vol. 10 no. 5
Type: Research Article
ISSN: 1355-2546

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Abstract

Purpose

Additive manufacturing (AM) or solid freeform fabrication (SFF) technique is extensively used to produce intrinsic 3D structures with high accuracy. Its significant contributions in the field of tissue engineering (TE) have significantly increased in the recent years. TE is used to regenerate or repair impaired tissues which are caused by trauma, disease and injury in human body. There are a number of novel materials such as polymers, ceramics and composites, which possess immense potential for production of scaffolds. However, the major challenge is in developing those bioactive and patient-specific scaffolds, which have a required controlled design like pore architecture with good interconnectivity, optimized porosity and microstructure. Such design not only supports cell proliferation but also promotes good adhesion and differentiation. However, the traditional techniques fail to fulfill all the required specific properties in tissue scaffold. The purpose of this study is to report the review on AM techniques for the fabrication of TE scaffolds.

Design/methodology/approach

The present review paper provides a detailed analysis of the widely used AM techniques to construct tissue scaffolds using stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), binder jetting (BJ) and advanced or hybrid additive manufacturing methods.

Findings

Subsequently, this study also focuses on understanding the concepts of TE scaffolds and their characteristics, working principle of scaffolds fabrication process. Besides this, mechanical properties, characteristics of microstructure, in vitro and in vivo analysis of the fabricated scaffolds have also been discussed in detail.

Originality/value

The review paper highlights the way forward in the area of additive manufacturing applications in TE field by following a systematic review methodology.

Details

Rapid Prototyping Journal, vol. 27 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 29 April 2020

Karen Lee Bar-Sinai, Tom Shaked and Aaron Sprecher

The purpose of the paper is to advance remote robotic fabrication through an iterative and pedagogical protocol for shaping architectural grounds. Advancements in…

Abstract

Purpose

The purpose of the paper is to advance remote robotic fabrication through an iterative and pedagogical protocol for shaping architectural grounds. Advancements in autonomous robotic tools enable to reach increasingly larger scales of architectural and landscape construction and operate in remote and inaccessible sites. In parallel, the relation of architecture to its environment is significantly reconsidered, as the building industry's contribution to the environmental stress increases. In response, new practices emerge, addressing the reshaping and modulation of environments using digital tools. The context of extra-terrestrial architecture provides a ground for exploring these issues, as future practice in this domain relies on the use of remote autonomous means for repurposing local matter. As a result, the novelty in robotic construction laboratories is tied to innovation in architectural pedagogy.

Design/methodology/approach

This paper puts forth a pedagogical protocol and iterative framework for digital groundscaping using robotic tools. The framework is demonstrated through an intensive workshop led by the authors. To situate the discussion, digital groundscaping is linked to several conditions that characterize practice and relate to pedagogy. These conditions include the experimental dimension of knowledge in digital fabrication, the convergence of knowledge as part of the blur between the fields of architecture and landscape architecture and the bridging of heterogeneous knowledge sets (virtual and physical), which robotic fabrication on natural terrains entails.

Findings

The outcomes of the workshop indicate that iterative processes can assist in applying autonomous design protocols on remote grounds. The protocols were assessed in light of the roles of technological tools, design iterations and material agency in the robotic fabrication.

Originality/value

The paper concludes with observations linking the iterative protocol to new avenues in architectural pedagogy as means of advancing the capacity to digitally design, modulate and transform natural grounds.

Details

Archnet-IJAR: International Journal of Architectural Research, vol. 14 no. 3
Type: Research Article
ISSN: 2631-6862

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Article
Publication date: 10 July 2020

Swapnil Vyavahare, Shailendra Kumar and Deepak Panghal

This paper aims to focus on an experimental study of surface roughness, dimensional accuracy and time of fabrication of parts produced by fused deposition modelling (FDM…

Abstract

Purpose

This paper aims to focus on an experimental study of surface roughness, dimensional accuracy and time of fabrication of parts produced by fused deposition modelling (FDM) technique of additive manufacturing. The fabricated parts of acrylonitrile butadiene styrene (ABS) material have pyramidal and conical features. Influence of five process parameters of FDM, namely, layer thickness, wall print speed, build orientation, wall thickness and extrusion temperature is studied on response characteristics. Furthermore, regression models for responses are developed and significant process parameters are optimized.

Design/methodology/approach

Comprehensive experimental study is performed using response surface methodology. Analysis of variance is used to investigate the influence of process parameters on surface roughness, dimensional accuracy and time of fabrication in both outer pyramidal and inner conical regions of part. Furthermore, a multi-response optimization using desirability function is performed to minimize surface roughness, improve dimensional accuracy and minimize time of fabrication of parts.

Findings

It is found that layer thickness and build orientation are significant process parameters for surface roughness of parts. Surface roughness increases with increase in layer thickness, while it decreases initially and then increases with increase in build orientation. Layer thickness, wall print speed and build orientation are significant process parameters for dimensional accuracy of FDM parts. For the time of fabrication, layer thickness and build orientation are found as significant process parameters. Based on the analysis, statistical non-linear quadratic models are developed to predict surface roughness, dimensional accuracy and time of fabrication. Optimization of process parameters is also performed using desirability function.

Research limitations/implications

The present study is restricted to the parts of ABS material with pyramidal and conical features only fabricated on FDM machine with delta configuration.

Originality/value

From the critical review of literature it is found that some researchers have made to study the influence of few process parameters on surface roughness, dimensional accuracy and time of fabrication of simple geometrical parts. Also, regression models and optimization of process parameters has been performed for simple parts. The present work is focussed on studying all these aspects in complicated geometrical parts with pyramidal and conical features.

Details

Rapid Prototyping Journal, vol. 26 no. 9
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 16 January 2009

Jae‐Won Choi, Ryan B. Wicker, Seok‐Hyun Cho, Chang‐Sik Ha and Seok‐Hee Lee

The paper's aim is to explore a method using light absorption for improving manufacturing of complex, three‐dimensional (3D) micro‐parts with a previously developed…

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2947

Abstract

Purpose

The paper's aim is to explore a method using light absorption for improving manufacturing of complex, three‐dimensional (3D) micro‐parts with a previously developed dynamic mask projection microstereolithography (MSL) system. A common issue with stereolithography systems and especially important in MSL is uncontrolled penetration of the ultraviolet light source into the photocrosslinkable resin when fabricating down‐facing surfaces. To accurately fabricate complex 3D parts with down‐facing surfaces, a chemical light absorber, Tinuvin 327™ was mixed in different concentrations into an acrylate‐based photocurable resin, and the solutions were tested for cure depths and successful micro‐part fabrication.

Design/methodology/approach

Tinuvin 327 was selected as the light absorber based on its high absorption characteristics (∼0.4) at 365 nm (the filtered light wavelength used in the MSL system). Four concentrations of Tinuvin 327 in resin were used (0.00, 0.05, 0.10, and 0.15 percent (w/w)), and cure depth experiments were performed. To investigate the effects of different concentrations of Tinuvin 327 on complex 3D microstructure fabrication, several microstructures with overhanging features such as a fan and spring were fabricated.

Findings

Results showed that higher concentrations of Tinuvin 327 reduced penetration depths and thus cure depths. For the resin with 0.15 percent (w/w) of the Tinuvin 327, a cure depth of ∼30 μm was achieved as compared to ∼200 μm without the light absorber. The four resin solutions were used to fabricate complex 3D microstructures, and different concentrations of Tinuvin 327 at a given irradiance and exposure energy were required for successful fabrication depending on the geometry of the micro‐part (concentrations of 0.05 and 0.1 percent (w/w) provided the most accurate builds for the fan and spring, respectively).

Research limitations/implications

Although two different concentrations of light absorber in solution were required to demonstrate successful fabrication for two different micro‐part geometries (a fan and spring), the experiments were performed using a single irradiance and exposure energy. A single solution with the light absorber could have possibly been used to fabricate these micro‐parts by varying irradiance and/or exposure energy, although the effects of varying these parameters on geometric accuracy, mechanical strength, overall manufacturing time, and other variables were not explored.

Originality/value

This work systematically investigated 3D microstructure fabrication using different concentrations of a light absorber in solution, and demonstrated that different light absorption characteristics were required for different down‐facing micro‐features.

Details

Rapid Prototyping Journal, vol. 15 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 30 May 2008

Evan Malone, Megan Berry and Hod Lipson

The paper's aim is to show the development of materials and methods which allow freeform fabrication of macroscopic Zn‐air electrochemical batteries. Freedom of geometric…

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1535

Abstract

Purpose

The paper's aim is to show the development of materials and methods which allow freeform fabrication of macroscopic Zn‐air electrochemical batteries. Freedom of geometric design may allow for new possibilities in performance optimization.

Design/methodology/approach

The authors have formulated battery materials which are compatible with solid freeform fabrication (SFF) while retaining electrochemical functionality. Using SFF processes, they have fabricated six Zn‐air cylindrical batteries and quantitatively characterized them and comparable commercial batteries. They analyze their performance in light of models from the literature and they also present SFF of a flexible two‐cell battery of unusual geometry.

Findings

Under continuous discharge to 0.25 V/cell with a 100 Ω load, the cylindrical cells have a specific energy and power density in the range of 40‐70 J/g and 0.4‐1 mW/cm2, respectively, with a mass range of 8‐18 g. The commercial Zn‐air button cells tested produce 30‐750 J/g and 7‐9 mW/cm2 under the same conditions, and have a mass range of 0.2‐2 g. The two‐cell, flexible Zn‐air battery produces a nominal 2.8 V, open‐circuit.

Research limitations/implications

The freeform‐fabricated batteries have ∼10 percent of the normalized performance of the commercial batteries. High‐internal contact resistance, loss of electrolyte through evaporation, and inferior catalyst reagent quality are possible causes of inferior performance. Complicated material preparation and battery fabrication processes have limited the number of batteries fabricated and characterized, limiting the statistical significance of the results.

Practical implications

Performance enhancement will be necessary before the packaging efficiency and design freedom provided by freeform‐fabricated batteries will be of practical value.

Originality/value

The paper demonstrates a multi‐material SFF system, material formulations, and fabrication methods which together allow the fabrication of complete functional Zn‐air batteries. It provides the first quantitative characterization of completely freeform‐fabricated Zn‐air batteries and comparison to objective standards, and shows that highly unusual, functional battery designs incorporating flexibility, multiple cells, and unusual geometry may be freeform fabricated.

Details

Rapid Prototyping Journal, vol. 14 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 May 2001

Feng Lin, Wei Sun and Yongnian Yan

A mathematical model to predict the layered process error and an optimization algorithm to define the fabricating orientation based on the minimum process error for…

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1065

Abstract

A mathematical model to predict the layered process error and an optimization algorithm to define the fabricating orientation based on the minimum process error for layered manufacturing fabrication has been developed. Case studies to determine the preferred orientation candidates for fabricating spherical objects, cube objects and objects with irregular geometrical shapes have been conducted and the results were used to validate the sensitivity, accuracy, and capability of the developed model and optimization algorithm. Different orientation candidates determined by minimum processing error and by minimum processing time were also compared. The developed model and the optimization algorithm can be used, in conjunction with other processing parameters such as processing time and support structure, to define an optimal processing planning for layered manufacturing fabrication.

Details

Rapid Prototyping Journal, vol. 7 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

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