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…
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.
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Sabri Erdem, Esra Aslanertik and Bengü Yardimci
This paper aims to empirically examine the main determinants of the compliance level of disclosure requirements for IAS 16, as well as factors that may explain the differences in…
Abstract
Purpose
This paper aims to empirically examine the main determinants of the compliance level of disclosure requirements for IAS 16, as well as factors that may explain the differences in the levels of compliance within companies.
Design/methodology/approach
The association between the level of compliance and various corporate characteristics was examined using Chi-square Automatic Interaction Detector (CHAID) analysis in financial disclosures for IAS 16. CHAID analysis was applied to the manufacturing companies listed in Borsa Istanbul for the years 2012 and 2013.
Findings
It was found that the most significant factor is the auditor reputation within different nodes such as size or free float rate. In most of the studies, correlation is used to determine the association between different factors, but this study is the first one that uses the CHAID analysis which offers an adjusted significance testing, and at the same time classification of the interaction between variables.
Research limitations/implications
This paper provides insights into the primary factors of disclosure compliance that help to improve the structure of disclosures and the level of compliance in preparing future financial reports. The proposed improvements will also support further developments in financial reporting regulations regarding disclosures. The key limitation in this paper is that it concentrates on a specific standard and only covers two years. However, it provides suggestions for one of the most important standards that includes various disclosures.
Originality/value
In addition, this paper fills a gap in the literature about the compliance level of specific standards such as IAS 16 and the usage of CHAID analysis in such studies. The results were consistent with some previous studies regarding the relationship between compliance level, auditor reputation and size and it also highlight the effect of different disclosure items on compliance level.
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Q. Sun, G.M. Rizvi, C.T. Bellehumeur and P. Gu
The purpose of this paper is to investigate the mechanisms controlling the bond formation among extruded polymer filaments in the fused deposition modeling (FDM) process. The…
Abstract
Purpose
The purpose of this paper is to investigate the mechanisms controlling the bond formation among extruded polymer filaments in the fused deposition modeling (FDM) process. The bonding phenomenon is thermally driven and ultimately determines the integrity and mechanical properties of the resultant prototypes.
Design/methodology/approach
The bond quality was assessed through measuring and analyzing changes in the mesostructure and the degree of healing achieved at the interfaces between the adjoining polymer filaments. Experimental measurements of the temperature profiles were carried out for specimens produced under different processing conditions, and the effects on mesostructures and mechanical properties were observed. Parallel to the experimental work, predictions of the degree of bonding achieved during the filament deposition process were made based on the thermal analysis of extruded polymer filaments.
Findings
Experimental results showed that the fabrication strategy, the envelope temperature and variations in the convection coefficient had strong effects on the cooling temperature profile, as well as on the mesostructure and overall quality of the bond strength between filaments. The sintering phenomenon was found to have a significant effect on bond formation, but only for the very short duration when the filament's temperature was above the critical sintering temperature. Otherwise, creep deformation was found to dominate changes in the mesostructure.
Originality/value
This study provides valuable information about the effect of deposition strategies and processing conditions on the mesostructure and local mechanical properties within FDM prototypes. It also brings a better understanding of phenomena controlling the integrity of FDM products. Such knowledge is essential for manufacturing functional parts and diversifying the range of application of this process. The findings are particularly relevant to work conducted on modeling of the process and for the formulation of materials new to the FDM process.
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M. Atif Yardimci and Selçuk Güçeri
Explains the fused deposition process and examines the rationale behind the cooling process model. Outlines the complexity of the problems and characteristics of fused deposition…
Abstract
Explains the fused deposition process and examines the rationale behind the cooling process model. Outlines the complexity of the problems and characteristics of fused deposition. Presents a general formulation for road cooling followed by results and their implications. Concludes with proposed directions for future work.
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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…
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 (E/ηa) 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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Tessa Jane Gordelier, Philipp Rudolf Thies, Louis Turner and Lars Johanning
Additive manufacturing or “3D printing” is a rapidly expanding sector and is moving from a prototyping service to a manufacturing service in its own right. With a significant…
Abstract
Purpose
Additive manufacturing or “3D printing” is a rapidly expanding sector and is moving from a prototyping service to a manufacturing service in its own right. With a significant increase in sales, fused deposition modelling (FDM) printers are now the most prevalent 3D printer on the market. The increase in commercial manufacturing necessitates an improved understanding of how to optimise the FDM printing process for various product mechanical properties. This paper aims to identify optimum print parameters for the FDM process to achieve maximum tensile strength through a review of recent studies in this field.
Design/methodology/approach
The effect of the governing printing parameters on the tensile strength of printed samples will be considered, including material selection, print orientation, raster angle, air gap and layer height.
Findings
The key findings include material recommendations, such as the use of emerging print materials like polyether-ether-ketone (PEEK), to produce samples with tensile strength over 200 per cent that of conventional materials such as acrylonitrile butadiene styrene (ABS). Amongst other parameters, it is shown that printing in the “upright” orientation should be avoided (samples can be up to 50 per cent weaker in this orientation) and air gap and raster width should be concurrently optimised to ensure good “inter-raster” bonding. The optimal choice of raster angle depends on print material; in ABS for example, selecting a 0° raster angle over a 90° angle can increase tensile strength by up to 100 per cent.
Originality/value
The paper conclusions provide researchers and practitioners with an up-to-date, single point reference, highlighting a series of robust recommendations to optimise the tensile strength of FDM-printed samples. Improving the mechanical performance of FDM-printed samples will support the continued growth of this technology as a viable production technique.
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Fernando Moura Duarte, José António Covas and Sidonie Fernandes da Costa
The performance of the parts obtained by fused filament fabrication (FFF) is strongly dependent on the extent of bonding between adjacent filaments developing during the…
Abstract
Purpose
The performance of the parts obtained by fused filament fabrication (FFF) is strongly dependent on the extent of bonding between adjacent filaments developing during the deposition stage. Bonding depends on the properties of the polymer material and is controlled by the temperature of the filaments when they come into contact, as well as by the time required for molecular diffusion. In turn, the temperature of the filaments is influenced by the set of operating conditions being used for printing. This paper aims at predicting the degree of bonding of realistic 3D printed parts, taking into consideration the various contacts arising during its fabrication, and the printing conditions selected.
Design/methodology/approach
A computational thermal model of filament cooling and bonding that was previously developed by the authors is extended here, to be able to predict the influence of the build orientation of 3D printed parts on bonding. The quality of a part taken as a case study is then assessed in terms of the degree of bonding, i.e. the percentage of volume exhibiting satisfactory bonding between contiguous filaments.
Findings
The complexity of the heat transfer arising from the changes in the thermal boundary conditions during deposition and cooling is well demonstrated for a case study involving a realistic 3D part. Both extrusion and build chamber temperature are major process parameters.
Originality/value
The results obtained can be used as practical guidance towards defining printing strategies for 3D printing using FFF. Also, the model developed could be directly applied for the selection of adequate printing conditions.
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Jose F. Rodriguez, James P. Thomas and John E. Renaud
Fused‐deposition (FD) is a robotically controlled “fiber” extrusion process that produces a new class of materials with a variety of controllable mesostructural features related…
Abstract
Fused‐deposition (FD) is a robotically controlled “fiber” extrusion process that produces a new class of materials with a variety of controllable mesostructural features related to fiber layout and the presence of voids. Mesostructural features of importance to the stiffness and strength of unidirectionally extruded materials were characterized as a function of the processing variables. Samples were made using the Stratasys FDM1600 Modeler with the P400 acrylonitrile‐butadiene‐styrene plastic. Results showed that the void geometry/density and the extent of bonding between contiguous fibers depended strongly on the fiber gap and extrusion flow rate. Settings for minimum void and maximum fiber‐to‐fiber bonding were determined. Void and bond length densities in the plane transverse to the fiber extrusion direction varied from 4 to 16 per cent and 39 to 73 per cent respectively. The results quantify the important mesostructural features as a function of the FD process variables and are expected to find use with other FD materials.
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José F. Rodríguez, James P. Thomas and John E. Renaud
Analytical/Computational models for the fused deposition (FD) material stiffness and strength as a function of mesostructural parameters are developed. Effective elastic moduli…
Abstract
Analytical/Computational models for the fused deposition (FD) material stiffness and strength as a function of mesostructural parameters are developed. Effective elastic moduli are obtained using the strength of materials approach and an elasticity approach based on the asymptotic theory of homogenization. Theoretical predictions for unidirectional FD‐acrylonitrile butadiene styrene materials are validated with experimentally determined values of moduli and strength. For moduli predictions, the results were found to be satisfactory with difference between experimental and theoretical values of less than 10 percent in most cases.
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Anna Bellini, Lauren Shor and Selcuk I. Guceri
To shift from rapid prototyping (RP) to agile fabrication by broadening the material selection, e.g. using ceramics, hence improving the properties (e.g. mechanical properties) of…
Abstract
Purpose
To shift from rapid prototyping (RP) to agile fabrication by broadening the material selection, e.g. using ceramics, hence improving the properties (e.g. mechanical properties) of fused deposition modeling (FDM) products.
Design/methodology/approach
This paper presents the development of a novel extrusion system, based on the FDM technology. The new set‐up, consisting of a mini‐extruder mounted on a high‐precision positioning system, is fed with bulk material in granulated form, instead that with the more common filament.
Findings
Previous research showed that the applications of new materials with specific characteristics in a commercial FDM system are limited by the use of intermediate precursors, i.e. a filament. The new design described in this paper overcomes the problem thanks to the new feeding system.
Research limitations/implications
The work presented in this paper is only the starting point for further development. The new system design was tested and encouraging improvements of the final product were achieved. However, several parameters, e.g. size of the feeding granules, still need to be optimized.
Practical implications
This configuration opens up opportunities for the use of wider range of materials, making the FDM to become a viable alternative manufacturing process for specialty products.
Originality/value
The mini‐extruder deposition system developed in this study exploits the advantages of the RP technologies: ability to shorten the product design and development time; suitability for automation; and ability to build many geometrically complex shapes. Hence, applying the described technology, it will be possible to manufacture customer‐driven product with important cost and time (from design to final product) savings.