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Article
Publication date: 1 December 2000

N. Venkataraman, S. Rangarajan, M.J. Matthewson, B. Harper, A. Safari, S.C. Danforth, G. Wu, N. Langrana, S. Guceri and A. Yardimci

Fused deposition of ceramics (FDC) is a solid freeform fabrication technique based on extrusion of highly loaded polymer systems. The process utilizes particle loaded…

3017

Abstract

Fused deposition of ceramics (FDC) is a solid freeform fabrication technique based on extrusion of highly loaded polymer systems. The process utilizes particle loaded thermoplastic binder feedstock in the form of a filament. The filament acts as both the piston driving the extrusion and also the feedstock being deposited. Filaments can fail during FDC via buckling, when the extrusion pressure needed is higher than the critical buckling load that the filament can support. Compressive elastic modulus determines the load carrying ability of the filament and the viscosity determines the resistance to extrusion (or extrusion pressure). A methodology for characterizing the compressive mechanical properties of FDC filament feedstocks has been developed. It was found that feedstock materials with a ratio (Ea) greater than a critical value (3×105 to 5×105 s‐1) do not buckle during FDC while those with a ratio less than this range buckle.

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

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Article
Publication date: 14 April 2014

Brian N. Turner, Robert Strong and Scott A. Gold

The purpose of this paper is to systematically and critically review the literature related to process design and modeling of fused deposition modeling (FDM) and similar…

14942

Abstract

Purpose

The purpose of this paper is to systematically and critically review the literature related to process design and modeling of fused deposition modeling (FDM) and similar extrusion-based additive manufacturing (AM) or rapid prototyping processes.

Design/methodology/approach

A systematic review of the literature focusing on process design and mathematical process modeling was carried out.

Findings

FDM and similar processes are among the most widely used rapid prototyping processes with growing application in finished part manufacturing. Key elements of the typical processes, including the material feed mechanism, liquefier and print nozzle; the build surface and environment; and approaches to part finishing are described. Approaches to estimating the motor torque and power required to achieve a desired filament feed rate are presented. Models of required heat flux, shear on the melt and pressure drop in the liquefier are reviewed. On leaving the print nozzle, die swelling and bead cooling are considered. Approaches to modeling the spread of a deposited road of material and the bonding of polymer roads to one another are also reviewed.

Originality/value

To date, no other systematic review of process design and modeling research related to melt extrusion AM has been published. Understanding and improving process models will be key to improving system process controls, as well as enabling the development of advanced engineering material feedstocks for FDM processes.

Details

Rapid Prototyping Journal, vol. 20 no. 3
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…

11321

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: 20 March 2017

Yedige Tlegenov, Yoke San Wong and Geok Soon Hong

Fused deposition modelling (FDM) is one of the most popular additive manufacturing processes, and is widely used for prototyping and fabricating low-cost customized parts. Current…

1297

Abstract

Purpose

Fused deposition modelling (FDM) is one of the most popular additive manufacturing processes, and is widely used for prototyping and fabricating low-cost customized parts. Current FDM machines have limited techniques to monitor process conditions to minimize process errors, such as nozzle clogging. Nozzle clogging is one of the most significant process errors in current FDM machines, and may cause serious consequences such as print failure. This paper aims to present a physics-based dynamic model suitable for monitoring nozzle clogging in FDM machines.

Design/methodology/approach

Liquefier mount of an FDM extruder is analysed as a beam excited by a uniform loading distributed over a partial length. Boundary conditions and applied loads for a direct-type FDM extruder are identified and discussed. Simulation of nozzle clogging was performed by using nozzles of different diameters from 0.5 to 0.2 mm, in step change of 0.1 mm. Sets of experiments were carried out by measuring vibrations of the liquefier block mount during FDM extrusion.

Findings

The mount of a liquefier block in an FDM extruder can be used to place a vibration sensor to monitor process errors such as nozzle clogging. Liquefier block mount’s transverse vibration amplitudes increase non-linearly when nozzle starts to block.

Practical implications

The proposed model can be effectively used for monitoring nozzle clogging in FDM machines, as it is based on the physics relating the FDM process parameters and the nozzle blockage.

Originality/value

The novelty of this paper is the unique method of modelling the FDM process dynamics that can be used for monitoring nozzle clogging.

Details

Rapid Prototyping Journal, vol. 23 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 17 October 2024

Sandra Rodríguez-Alvarez, Laura del Río del Río-Fernández, Daniel del Río-Santos, Carmen de la Torre-Gamarra, Belen Levenfeld and Alejandro Varez

This study aims to develop a highly loaded filament with spherical metallic particles for fused filament fabrication (FFF) technology. The research focuses on optimizing powder…

51

Abstract

Purpose

This study aims to develop a highly loaded filament with spherical metallic particles for fused filament fabrication (FFF) technology. The research focuses on optimizing powder loading, printing parameters and final processes, including debinding and sintering, to produce successful metal parts.

Design/methodology/approach

The optimal powder loading was identified by measuring mixing torque and viscosity at various temperatures. The filament was extruded, and printing parameters − particularly printing speed to ensure proper material flow − were optimized. Different filling patterns were also examined. After printing, the polymeric binder was removed and the parts were sintered to form the final metal components.

Findings

The optimal powder loading was determined to be 55 vol.%. The best surface quality was achieved with an optimized printing speed of 5 mm/s. Parts printed with various infill patterns were studied for differences in open, closed and total porosity, showing a strong link between porosity and infill pattern.

Originality/value

This comprehensive study provides new insights into manufacturing metal parts using FFF technology. It fills a gap in the literature regarding feedstock viscosity and shear rate in highly loaded metal filaments during FFF. Additionally, it uniquely examines the open, closed and total porosity of metal parts printed with different infill patterns.

Details

Rapid Prototyping Journal, vol. 31 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 30 July 2019

Jack Hinton, Dejan Basu, Maria Mirgkizoudi, David Flynn, Russell Harris and Robert Kay

The purpose of this paper is to develop a hybrid additive/subtractive manufacturing platform for the production of high density ceramic components.

236

Abstract

Purpose

The purpose of this paper is to develop a hybrid additive/subtractive manufacturing platform for the production of high density ceramic components.

Design/methodology/approach

Fabrication of near-net shape components is achieved using 96 per cent Al3O2 ceramic paste extrusion and a planarizing machining operations. Sacrificial polymer support can be used to aid the creation of overhanging or internal features. Post-processing using a variety of machining operations improves tolerances and fidelity between the component and CAD model while reducing defects.

Findings

This resultant three-dimensional monolithic ceramic components demonstrated post sintering tolerances of ±100 µm, surface roughness’s of ∼1 µm Ra, densities in excess of 99.7 per cent and three-point bending strength of 221 MPa.

Originality/value

This method represents a novel approach for the digital fabrication of ceramic components, which provides improved manufacturing tolerances, part quality and capability over existing additive manufacturing approaches.

Details

Rapid Prototyping Journal, vol. 25 no. 6
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 12 September 2022

Kofi Agyekum, Samuel Amos-Abanyie, Victoria Maame Afriyie Kumah, Augustine Senanu Komla Kukah and Burcu Salgin

There are significantly fewer women than men in managerial positions, mainly project management. This problem is noticeable in the construction and engineering sectors…

983

Abstract

Purpose

There are significantly fewer women than men in managerial positions, mainly project management. This problem is noticeable in the construction and engineering sectors, traditionally male-dominated industries with leadership much dependent on masculine qualities. This study examines the obstacles to the career progression of professional female project managers (PFPMs) in the Ghanaian construction industry.

Design/methodology/approach

Twenty potential obstacles to women's career progression in the construction industry were identified from a comprehensive review of the literature. A questionnaire was prepared and administered among eighty project managers who work in large construction firms in Ghana. Data obtained were analysed using one sample t-test, Kendall's concordance test, Chi-square test and exploratory factor analysis.

Findings

The findings suggest the significance of all the twenty factors as potential obstacles to the career progression of PFPMs. The exploratory factor analysis identified five underlying grouped obstacles: “leadership and human capital related issues”, “issues related to discrimination of all forms”, “career aspiration and planning issues”, “female related role conflicts”, and “recruitment and selection issues”.

Research limitations/implications

The subjective nature of the views of the respondents could influence the evaluation of the obstacles. With this study only exploring the dimensions underlying the significant obstacles, future studies could examine the interrelationships between the various obstacles and move on to determine their impacts on the career progression of professional female PMs as well.

Practical implications

Having an in-depth understanding of these obstacles, stakeholders and other industry practitioners in Ghana could make informed decisions on measures to put in place to address some of these critical issues to raise the standard of professional female PMs in the construction industry. Policymakers and gender advocates in Ghana could also take up some of the critical obstacles identified and provide suitable strategies to educate and create the needed awareness of the industry on those obstacles. Practically, the findings from this study can be valuable for informing decision-making at different management levels in the construction industry.

Originality/value

With country-specific (Ghana) obstacles identified, the findings significantly contribute to the literature on the career advancement of females in the construction sector.

Details

Engineering, Construction and Architectural Management, vol. 31 no. 1
Type: Research Article
ISSN: 0969-9988

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Article
Publication date: 15 November 2019

Jie Leng, Junjie Wu, Ning Chen, Xiang Xu and Jie Zhang

This paper aims to develop an integrated and portable desktop 3D printer using direct extruding technology to expand applied material field. Different from conventional fused…

626

Abstract

Purpose

This paper aims to develop an integrated and portable desktop 3D printer using direct extruding technology to expand applied material field. Different from conventional fused deposition modeling (FDM) which uses polymer filaments as feedstock, the developed system can fabricate products directly using polymer pellets. And its printing properties are also investigated.

Design/methodology/approach

A conical screw-based extrusion deposition (CSBED) system was developed with a large taper conical screw to plasticize and extrude fed materials. The 3D printer was developed with assistance of precision positioning and controlling system. Biocompatible thermoplastic polyurethane (TPU) pellets were selected as raw materials for experiments. The influences of four processing parameters: nozzle temperature, fill vector orientation, layer thickness and infill density on the product’s internal structure and tensile properties were investigated.

Findings

It is concluded that the customized system has a high manufacturing accuracy with a diminutive global size and is suitable for printing soft materials such as TPU. Theoretical calculation shows the developed conical screw is more effective in plasticizing and extruding compared with conventional screw. Printed samples can achieve applicable tensile properties under harmonious parameter cooperation. Deposited materials are found to have voids among adjacent roads under unbefitting parameters.

Originality/value

The developed system efficiently improves material limitations compared to commercial FDM systems and exhibits great potential in medical field because soft materials such as biocompatible TPU pellets can be directly used.

Details

Rapid Prototyping Journal, vol. 26 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 2 September 2021

Mattia Mele, Michele Ricciarelli and Giampaolo Campana

Powder bed additive manufacturing processes are widespread due to their many technical and economic advantages. Nevertheless, the disposal of leftover powder poses a problem in…

203

Abstract

Purpose

Powder bed additive manufacturing processes are widespread due to their many technical and economic advantages. Nevertheless, the disposal of leftover powder poses a problem in terms of process sustainability. The purpose of this paper is to provide an alternative solution to recycle waste PA12 powder from HP multi jet fusion. In particular, the opportunity to use this material as a dispersion in three-dimensional (3D) printed clay is investigated.

Design/methodology/approach

A commercial fused deposition modelling printer was re-adapted to extrude a viscous paste composed of clay, PA12 and water. Once printed, parts were dried and then put in an oven to melt the polymer fraction. Four compositions with different PA12 concentration were studied. First, the extrudability of the paste was observed by testing different extrusion lengths. Then, the surface porosities were evaluated through microscopical observations of the manufactured parts. Finally, benchmarks with different geometries were digitalised via 3D scanning to analyse the dimensional alterations arising at each stage of the process.

Findings

Overall, the feasibility of the process is demonstrated. Extrusion tests revealed that the composition of the paste has a minor influence on the volumetric flow rate, exhibiting a better consistency in the case of long extrusions. The percentage of surface cavities was proportional to the polymer fraction contained in the mix. From dimensional analyses, it was possible to conclude that PA12 reduced the degree of shrinkage during the drying phase, while it increased dimensional alterations occurring in the melting phase. The results showed that the dimensional error measured on the z-axis was always higher than that of the XY plane.

Practical implications

The method proposed in this paper provides an alternative approach to reuse leftover powders from powder bed fusion processes via another additive manufacturing process. This offers an affordable and open-source solution to companies dealing with polymer powder bed fusion, allowing them to reduce their environmental impacts while expanding their production.

Originality/value

The paper presents an innovative additive manufacturing solution for powder reuse. Unlike the recycling methods in the body of literature, this solution does not require any intermediate transformation process, such as filament fabrication. Also, the cold material deposition enables the adoption of very inexpensive extrusion equipment. This preliminary study demonstrates the feasibility and the benefits of this process, paving the way for numerous future studies.

Details

Rapid Prototyping Journal, vol. 28 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 December 2005

S.H. Masood and W.Q. Song

Presents development and characterisation of a new metal/polymer composite material for use in fused deposition modelling (FDM) rapid prototyping process with the aim of…

4033

Abstract

Purpose

Presents development and characterisation of a new metal/polymer composite material for use in fused deposition modelling (FDM) rapid prototyping process with the aim of application to direct rapid tooling. The work represents a major development in reducing the cost and time in rapid tooling.

Design/methodology/approach

The material consists of iron particles in a nylon type matrix. The detailed formulation and characterisation of the thermal properties of the various combinations of the new composites are investigated experimentally. Results are compared with other metal/polymer composites used in rapid tooling.

Findings

The feedstock filaments of this composite have been produced and used successfully in the unmodified FDM system for direct rapid tooling of injection moulding inserts. Thermal properties are found to be acceptable for rapid tooling applications for injection moulding.

Originality/value

Introduces an entirely new metal based composite material for direct rapid tooling application using FDM RP system with desired thermal properties and characteristics. This will reduce the cost and time of manufacturing tooling inserts and dies for injection moulding.

Details

Assembly Automation, vol. 25 no. 4
Type: Research Article
ISSN: 0144-5154

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