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Article
Publication date: 1 December 1995

P.M. Dickens, R. Stangroom, M. Greul, B. Holmer, K.K.B. Hon, R. Hovtun, R. Neumann, S. Noeken and D. Wimpenny

The Tooling and Casting subgroup of the European Action on Rapid Prototyping (EARP) has undertaken a project to investigate the problems associated with using rapid prototype…

1394

Abstract

The Tooling and Casting subgroup of the European Action on Rapid Prototyping (EARP) has undertaken a project to investigate the problems associated with using rapid prototype models as sacrificial patterns for investment casting. The accuracy and surface finish of the models and the castings were also assessed so that a comparison could be made. Models from each process were manufactured by different members of EARP and then three foundries were each given a set of models to convert to castings. Observes that one of the oldest metal manufacturing techniques, which dates back to 4000‐6000 BC, is being used with one of the most modern ‐ rapid prototyping.

Details

Rapid Prototyping Journal, vol. 1 no. 4
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 20 April 2015

Brian N. Turner and Scott A Gold

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…

11331

Abstract

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.

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Article
Publication date: 18 January 2016

Sunpreet Singh and Rupinder Singh

This paper aims to review the industrial and biomedical applications of state-of-the-art fused deposition modelling (FDM)-assisted investment casting (FDMAIC). Brief literature…

1344

Abstract

Purpose

This paper aims to review the industrial and biomedical applications of state-of-the-art fused deposition modelling (FDM)-assisted investment casting (FDMAIC). Brief literature survey of methodologies, ideas, techniques and approaches used by various researchers is highlighted and use of hybrid feedstock filament-based pattern to produce metal matrix composite is duly discussed.

Design/methodology/approach

Pattern replica required for investment casting (IC) of biomedical implant, machine parts, dentistry and other industrial components can be directly produced by using FDM process is presented. Relevant studies and examples explaining the suitability of FDMAIC for various applications are also presented.

Findings

Researches to optimize the conventional IC with FDM solutions and develop new hybrid feedstock filament of FDM done by researchers worldwide are also discussed. The review highlights the benefit of FDMAIC to surgeons, engineers and manufacturing organizations.

Research limitations/implications

The research related to this survey is limited to the suitability and applicability of FDMAIC.

Originality/value

This review presents the information regarding potential IC application, which facilitates the society, engineers and manufacturing organizations by providing variety of components for assisting FDM. The information reported in this paper will serve doctors, researchers, organizations and academicians to explore the new options in the field of FDMAIC.

Details

Rapid Prototyping Journal, vol. 22 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 31 July 2009

Dilip Sahebrao Ingole, Abhay Madhusudan Kuthe, Shashank B. Thakare and Amol S. Talankar

The purpose of this paper is to apply rapid prototyping (RP) philosophy as a technology transfer in industries to take its time and cost‐effective advantages for development of…

2232

Abstract

Purpose

The purpose of this paper is to apply rapid prototyping (RP) philosophy as a technology transfer in industries to take its time and cost‐effective advantages for development of rapid tooling (RT).

Design/methodology/approach

Experimentations are performed for development of RT for sand casting, investment casting and plastic moulding applications.

Findings

This paper reports the procedures developed for manufacture of production tooling using RP. A cost/benefit model is developed to justify implementation of RP as a technology transfer in industries.

Research limitations/implications

The examples are limited to parts build by fused deposition modelling RP process. However, the concepts experimented may be applied for other RP processes.

Practical implications

RP has proved to be a cost‐effective and time‐efficient approach for development of RT, thereby ensuring possibility for technology transfer in casting as well as plastic industries.

Originality/value

This is the pioneer attempt towards quantifying RP benefits, in view of technology transfer. This paper presents original case studies and findings on the basis of experimentations performed in foundries.

Details

Rapid Prototyping Journal, vol. 15 no. 4
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 31 July 2009

Haihua Wu, Dichen Li and Nannan Guo

The purpose of this paper is to develop a novel process of integral ceramic molds for investment casting of hollow turbine blades.

2248

Abstract

Purpose

The purpose of this paper is to develop a novel process of integral ceramic molds for investment casting of hollow turbine blades.

Design/methodology/approach

At first, a resin pattern of a hollow turbine blade prototype is fabricated by stereolithography (SL). And then aqueous gelcasting process is utilized to fill the resin pattern with ceramic slurry of low viscosity and low shrinkage, through in situ polymerization of the slurry a ceramic mold is formed. At last, the ceramic mold for investment casting of hollow turbine blade is obtained by vacuum drying, pyrolyzing and sintering.

Findings

An integral ceramic mold is successfully fabricated by combining SL and gelcasting process, cores and shell are connected with each other and thus high relative position accuracy is guaranteed. Properties of integral ceramic mold at room temperature and high temperature satisfy the requirements of directional casting for complex‐shaped thin‐walled blades.

Research limitations/implications

Because the integral ceramic mold is a close body, it is very difficult to directly measure its inner dimensions and the relative position accuracy of cores and shell, and the further research is needed.

Originality/value

This method enhanced the versatility of using SL prototype in the fabrication of integral ceramic mold for investment castings. Although this paper took a hollow turbine blade as an example, this method is also capable of fabricating integral ceramic molds for other complex investment castings.

Details

Rapid Prototyping Journal, vol. 15 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Available. Open Access. Open Access
Article
Publication date: 27 June 2019

Younss Ait Mou and Muammer Koc

This paper aims to report on the findings of an investigation to compare three different three-dimensional printing (3DP) or additive manufacturing technologies [i.e. fused…

1689

Abstract

Purpose

This paper aims to report on the findings of an investigation to compare three different three-dimensional printing (3DP) or additive manufacturing technologies [i.e. fused deposition modeling (FDM), stereolithography (SLA) and material jetting (MJ)] and four different equipment (FDM, SLA, MJP 2600 and Object 260) in terms of their dimensional process capability (dimensional accuracy and surface roughness). It provides a comprehensive and comparative understanding about the level of attainable dimensional accuracy, repeatability and surface roughness of commonly used 3DP technologies. It is expected that these findings will help other researchers and industrialists in choosing the right technology and equipment for a given 3DP application.

Design/methodology/approach

A benchmark model of 5 × 5 cm with several common and challenging features, such as around protrusion and hole, flat surface, micro-scale ribs and micro-scale long channels was designed and printed repeatedly using four different equipment of three different 3DP technologies. The dimensional accuracy of the printed models was measured using non-contact digital measurement methods. The surface roughness was evaluated using a digital profilometer. Finally, the surface quality and edge sharpness were evaluated under a reflected light ZEISS microscope with a 50× magnification objective.

Findings

The results show that FDM technology with the used equipment results in a rough surface and loose dimensional accuracy. The SLA printer produced a smoother surface, but resulted in the distortion of thin features (<1 mm). MJ printers, on the other hand, produced comparable surface roughness and dimensional accuracy. However, ProJet MJP 3600 produced sharper edges when compared to the Objet 260 that produced round edges.

Originality/value

This paper, for the first time, provides a comprehensive comparison of three different commonly used 3DP technologies in terms of their dimensional capability and surface roughness without farther post-processing. Thus, it offers a reliable guideline for design consideration and printer selection based on the target application.

Details

Rapid Prototyping Journal, vol. 25 no. 5
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 May 2006

K. Dotchev and S. Soe

The main objective of this paper is to analyse all stages of the CastForm™ polystyrene (CF) pattern fabrication process, identify the reasons leading to inferior quality, and…

1654

Abstract

Purpose

The main objective of this paper is to analyse all stages of the CastForm™ polystyrene (CF) pattern fabrication process, identify the reasons leading to inferior quality, and outline techniques for its improvement and reduction of failures.

Design/methodology/approach

This paper describes rapid manufacturing of patterns for shell or flask investment casting using the laser sintering (LS) technique with CF material. The process involves data preparation, LS fabrication of a “green” part, cleaning, and wax infiltration. All process stages are equally important for successful project completion in terms of pattern quality and delivery time. A failure at any stage requires a part or pattern to be produced again, which would incur additional time and cost.

Findings

The conducted experiments show how the CF material strength varies at different process stages and temperatures. Cleaning and wax infiltration are considered the main reasons for part distortion and breakage.

Originality/value

The paper proposes a new approach for wax infiltration. Deformation and breaking of unsupported features could be reduced or eliminated by introducing a supporting structure under these features.

Details

Rapid Prototyping Journal, vol. 12 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 6 February 2017

Sahin Yigit and Nilanjan Chakraborty

This paper aims to investigate the aspect ratio (AR; ratio of enclosure height:length) dependence of steady-state Rayleigh–Bénard convection of Bingham fluids within rectangular…

171

Abstract

Purpose

This paper aims to investigate the aspect ratio (AR; ratio of enclosure height:length) dependence of steady-state Rayleigh–Bénard convection of Bingham fluids within rectangular enclosures for both constant wall temperature and constant wall heat flux boundary conditions. A nominal Rayleigh number range 103 ≤ Ra ≤ 105 (Ra defined based on the height) for a single representative value of nominal Prandtl number (i.e. Pr = 500) has been considered for 1/4 ≤ AR ≤ 4.

Design/methodology/approach

The bi-viscosity Bingham model is used to mimic Bingham fluids for Rayleigh–Bénard convection of Bingham fluids in rectangular enclosures. The conservation equations of mass, momentum and energy have been solved in a coupled manner using the finite volume method where a second-order central differencing scheme is used for the diffusive terms and a second-order up-wind scheme is used for the convective terms. The well-known semi-implicit method for pressure-linked equations algorithm is used for the coupling of the pressure and velocity.

Findings

It has been found that buoyancy-driven flow strengthens with increasing nominal Rayleigh number Ra, but the convective transport weakens with increasing Bingham number Bn, because of additional flow resistance arising from yield stress in Bingham fluids. The relative contribution of thermal conduction (advection) to the total thermal transport strengthens (diminishes) with increasing AR for a given set of values of Ra and Pr for both Newtonian and Bingham fluids for both boundary conditions, and the thermal transport takes place purely because of conduction for tall enclosures.

Originality/value

Correlations for the mean Nusselt number Nu ¯ have been proposed for both boundary conditions for both Newtonian and Bingham fluids using scaling arguments, and the correlations have been demonstrated to predict Nu ¯ obtained from simulation data for 1/4 ≤ AR ≤ 4, 103Ra ≤ 105 and Pr = 500.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 2
Type: Research Article
ISSN: 0961-5539

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Book part
Publication date: 1 October 2015

Bill B. Francis, Iftekhar Hasan and Eric Ofori

This paper investigates the impact of the development of capital markets on economic growth in Africa and reports a significant increase in real GDP per capita after stock…

Abstract

This paper investigates the impact of the development of capital markets on economic growth in Africa and reports a significant increase in real GDP per capita after stock exchanges are established. This paper also reveals that there are significant improvements in the level of private investments in the post stock market launch era. The results also indicate that stock markets play a complementary role to the banking sector by contributing to the availability of private credit. Although African capital markets are relatively less advanced when compared to capital markets on other continents (particularly in terms of technology, structure, and liquidity), we find that their establishment has been crucial in helping African countries catch up with the rest of the world.

Details

International Corporate Governance
Type: Book
ISBN: 978-1-78560-355-6

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Article
Publication date: 31 October 2018

Colin Jones

The purpose of this paper is to address the increasing demand for entrepreneurship education (EE) across all levels of education globally. Specifically, the need to identify a…

1894

Abstract

Purpose

The purpose of this paper is to address the increasing demand for entrepreneurship education (EE) across all levels of education globally. Specifically, the need to identify a signature pedagogy for entrepreneurship that can be used in all teaching and learning contexts associated with all forms of EE.

Design/methodology/approach

This conceptual paper draws upon the seminal work of Lee Shulman to contemplate and propose a signature pedagogy for EE. Contemporary ideas from the scholarship of teaching and learning (SoTL) literature are also used to develop a sound pedagogical foundation for the approach advocated.

Findings

This paper proposes an innovative solution that addresses the challenge of defining what minimally speaking, is EE? The development of a signature pedagogy for EE provides clarity around the challenge of developing a standard minimalist approach to teaching entrepreneurship.

Practical implications

There are important implications that arise from this paper for all educators of entrepreneurship. Most importantly being that we can all share a SoTL regardless of the context of the author’s teaching.

Originality/value

This paper presents new thinking that has the potential to fundamentally reshape how we conceive the process of designing and delivering EE. Importantly, this paper contributes to the future development of SoTL in EE.

Details

Journal of Small Business and Enterprise Development, vol. 26 no. 2
Type: Research Article
ISSN: 1462-6004

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