Search results

1 – 10 of 12
Per page
102050
Citations:
Loading...
Access Restricted. View access options
Article
Publication date: 18 May 2021

Anabel Renteria, Luisa F. Garcia, Jorge A. Diaz, Luis C. Delfin, Jaime E. Regis, Elizabeth I. Reza, David Espalin, Tzu-Liang Bill Tseng and Yirong Lin

The purpose of this study is to evaluate different 3D structures for humidity sensing that will enable the fabrication of complex geometries with high moisture sensitivity.

278

Abstract

Purpose

The purpose of this study is to evaluate different 3D structures for humidity sensing that will enable the fabrication of complex geometries with high moisture sensitivity.

Design/methodology/approach

Humidity sensors based on alumina ceramics were fabricated using direct ink write (DIW) technique. Different engineered surface area, polymer binder ratio and post-processing treatment were considered to increase moisture sensitivity.

Findings

It was found that the binder ratio plays an important role in controlling the rheology of the paste during printing and determining the pore size after post-processing treatment. The sensibility of the fabricated humidity sensor was investigated by measuring its capacitance response toward relative humidity (RH) varying from 40% to 90% RH at 25°C. It is shown that using 3D lattice design, printed alumina humidity sensor could improve sensitivity up to 31.6 pF/RH%, over an order of magnitude higher than solid alumina.

Originality/value

Most of the alumina humidity sensors available are films in nature because of manufacturing difficulties, which limited its potential of higher sensitivity, and thus broader applications. In this paper, a novel 3D alumina humidity sensor was fabricated using DIW 3D printing technology.

Details

Rapid Prototyping Journal, vol. 27 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 14 April 2014

David Espalin, Jorge Alberto Ramirez, Francisco Medina and Ryan Wicker

The purpose of this paper is to investigate a build process variation for fused deposition modeling (FDM) in which contours and rasters (also referred to as internal fill…

3842

Abstract

Purpose

The purpose of this paper is to investigate a build process variation for fused deposition modeling (FDM) in which contours and rasters (also referred to as internal fill patterns) are built using different layer thicknesses and road widths. In particular, the paper examines the effect of the build process variation on surface roughness, production times and mechanical properties. Additionally, a unique FDM process was developed that enabled the deposition of discrete multiple materials at different layers and regions within layers.

Design/methodology/approach

A multi-material, multi-technology FDM system was developed and constructed to enable the production of parts using either discrete multi-materials or the build process variation (variable layer thickness and road width). Two legacy FDM machines were modified and installed onto a single manufacturing system to allow the strategic, spatially controlled thermoplastic deposition with multiple extrusion nozzles of multiple materials during the same build. This automated process was enabled by the use of a build platform attached to a pneumatic slide that moved the platform between the two FDM systems, an overall control system, a central PC and a custom-made program (FDMotion) and graphic user interface. The term multi-technology FDM system used here implies the two FDM systems and the integration of these systems into a single manufacturing environment using the movable platform and associated hardware and software. Future work will integrate additional technologies within this system. Parts produced using the build process variation utilized internal roads with 1,524 μm road width and 508 μm layer height, while the contours used 254 μm road width and 127 μm layer height. Measurements were performed and compared to standard FDM parts that included surface roughness of planes at different inclinations, tensile testing and fabrication times.

Findings

Results showed that when compared to the standard FDM process, the parts produced using the build process variation exhibited the same tensile properties as determined by a student's t-test (p-values > 0.05, μ1-μ2 = 0, n = 5). Surface roughness measurements revealed that the process variation resulted in surface roughness (Ra) improvements of 55, 43, 44 and 38 per cent for respective planes inclined at 10, 15, 30 and 45° from vertical. In addition, for a 50.8 × 50.8 mm square section (25.4 mm tall), the build process variation required a minimum of 2.8 hours to build, while the standard FDM process required 6.0 hours constituting a 53 per cent reduction in build time. Finally, several manufacturing demonstrations were performed including the fabrication of a discrete PC-ABS sandwich structure containing tetragonal truss core elements.

Originality/value

This paper demonstrates a build strategy that varies contour and raster widths and layer thicknesses for FDM that can be used to improve surface roughness – a characteristic that has historically been in need of improvement – and reduce fabrication time while retaining mechanical properties.

Details

Rapid Prototyping Journal, vol. 20 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 27 April 2010

David Espalin, Karina Arcaute, David Rodriguez, Francisco Medina, Matthew Posner and Ryan Wicker

The purpose of this paper is to investigate the use of medical‐grade polymethylmethacrylate (PMMA) in fused deposition modeling (FDM) to fabricate porous customized freeform…

2774

Abstract

Purpose

The purpose of this paper is to investigate the use of medical‐grade polymethylmethacrylate (PMMA) in fused deposition modeling (FDM) to fabricate porous customized freeform structures for several applications including craniofacial reconstruction and orthopaedic spacers. It also aims to examine the effects of different fabrication conditions on porosity and mechanical properties of PMMA samples.

Design/methodology/approach

The building parameters and procedures to properly and consistently extrude PMMA filament in FDM for building 3D structures were determined. Two experiments were performed that examined the effects of different fabrication conditions, including tip wipe frequency, layer orientation, and air gap (AG) (or distance between filament edges) on the mechanical properties and porosity of the fabricated structures. The samples were characterized through optical micrographs, and measurements of weight and dimensions of the samples were used to calculate porosity. The yield strength, strain, and modulus of elasticity of the samples were determined through compressive testing.

Findings

Results show that both the tip wipe frequency (one wipe every layer or one wipe every ten layers) and layer orientation (transverse or axial with respect to the applied compressive load) used to fabricate the scaffolds have effects on the mechanical properties and resulting porosity. The samples fabricate in the transverse orientation with the high tip wipe frequency have a larger compressive strength and modulus than the lower tip wipe frequency samples (compressive strength: 16±0.97 vs 13±0.71 MPa, modulus: 370±14 vs 313±29 MPa, for the high vs low tip wipe frequency, respectively). Also, the samples fabricated in the transverse orientation have a larger compressive strength and modulus than the ones fabricated in the axial orientation (compressive strength: 16±0.97 vs 13±0.83 MPa, modulus: 370±14 vs 281±22 MPa; for samples fabricated with one tip wipe per layer in the transverse and axial orientations, respectively). In general, the stiffness and yield strength decreased when the porosity increased (compressive strength: 12±0.71 to 7±0.95 MPa, Modulus: 248±10 to 165±16 MPa, for samples with a porosity ranging from 55 to 70 percent). As a demonstration, FDM is successfully used to fabricate patient‐specific, 3D PMMA implants with varying densities, including cranial defect repair and femur models.

Originality/value

This paper demonstrates that customized, 3D, biocompatible PMMA structures with varying porosities can be designed and directly fabricated using FDM. By enabling the use of PMMA in FDM, medical implants such as custom craniofacial implants can be directly fabricated from medical imaging data improving the current state of PMMA use in medicine.

Details

Rapid Prototyping Journal, vol. 16 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 20 March 2017

Timothy J. Coogan and David Owen Kazmer

The purpose of this paper is to investigate the factors governing bond strength in fused deposition modeling (FDM) compared to strength in the fiber direction.

1919

Abstract

Purpose

The purpose of this paper is to investigate the factors governing bond strength in fused deposition modeling (FDM) compared to strength in the fiber direction.

Design/methodology/approach

Acrylonitrile butadiene styrene (ABS) boxes with the thickness of a single fiber were made at different platform and nozzle temperatures, print speeds, fiber widths and layer heights to produce multiple specimens for measuring the strength.

Findings

Specimens produced with the fibers oriented in the tensile direction had 95 per cent of the strength of the constitutive filament. Bond strengths ranged from 40 to 85 per cent of the filament strength dependent on the FDM processing conditions. Diffusion, wetting and intimate contact all separately affect bond strength.

Practical implications

This study provides processing recommendations for producing the strongest FDM parts. The needs for higher nozzle temperatures and more robust feed motors are described; these recommendations can be useful for companies producing FDM products as well as companies designing FDM printers.

Originality/value

This is the first study that discusses wetting and intimate contact separately in FDM, and the results suggest that a fundamental, non-empirical model for predicting FDM bond strength can be developed based on healing models. Additionally, the role of equilibration time at the start of extrusion as well as a motor torque limitation while trying to print at high speeds are described.

Details

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

Keywords

Access Restricted. View access options
Article
Publication date: 20 June 2017

Jason T. Cantrell, Sean Rohde, David Damiani, Rishi Gurnani, Luke DiSandro, Josh Anton, Andie Young, Alex Jerez, Douglas Steinbach, Calvin Kroese and Peter G. Ifju

This paper aims to present the methodology and results of the experimental characterization of three-dimensional (3D) printed acrylonitrile butadiene styrene (ABS) and…

3612

Abstract

Purpose

This paper aims to present the methodology and results of the experimental characterization of three-dimensional (3D) printed acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) parts utilizing digital image correlation (DIC).

Design/methodology/approach

Tensile and shear characterizations of ABS and PC 3D-printed parts were performed to determine the extent of anisotropy present in 3D-printed materials. Specimens were printed with varying raster ([+45/−45], [+30/−60], [+15/−75] and [0/90]) and build orientations (flat, on-edge and up-right) to determine the directional properties of the materials. Tensile and Iosipescu shear specimens were printed and loaded in a universal testing machine utilizing two-dimensional (2D) DIC to measure strain. The Poisson’s ratio, Young’s modulus, offset yield strength, tensile strength at yield, elongation at break, tensile stress at break and strain energy density were gathered for each tensile orientation combination. Shear modulus, offset yield strength and shear strength at yield values were collected for each shear combination.

Findings

Results indicated that raster and build orientations had negligible effects on the Young’s modulus or Poisson’s ratio in ABS tensile specimens. Shear modulus and shear offset yield strength varied by up to 33 per cent in ABS specimens, signifying that tensile properties are not indicative of shear properties. Raster orientation in the flat build samples reveals anisotropic behavior in PC specimens as the moduli and strengths varied by up to 20 per cent. Similar variations were observed in shear for PC. Changing the build orientation of PC specimens appeared to reveal a similar magnitude of variation in material properties.

Originality/value

This article tests tensile and shear specimens utilizing DIC, which has not been employed previously with 3D-printed specimens. The extensive shear testing conducted in this paper has not been previously attempted, and the results indicate the need for shear testing to understand the 3D-printed material behavior fully.

Details

Rapid Prototyping Journal, vol. 23 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 27 September 2024

Elmira Sharabian, Mahyar Khorasani, Stefan Gulizia, Amir Hossein Ghasemi, Eric MacDonald, David Downing, Bernard Rolfe, Milan Brandt and Martin Leary

This study aims to comprehensively investigate the electron beam powder bed fusion (EB-PBF) process for copper, offering validated estimations of melt pool temperature and…

101

Abstract

Purpose

This study aims to comprehensively investigate the electron beam powder bed fusion (EB-PBF) process for copper, offering validated estimations of melt pool temperature and morphology through numerical and analytical approaches. This work also assesses how process parameters influence the temperature fluctuations and the morphological changes of the melt pool.

Design/methodology/approach

Two distinct methods, an analytical model and a numerical simulation, were used to assess temperature profiles, melt pool morphology and associated heat transfer mechanisms, including conduction and keyhole mode. The analytical model considers conduction as the dominant heat transfer mechanism; the numerical model also includes convection and radiation, incorporating specific parameters such as beam power, scan speed, thermophysical material properties and powder interactions.

Findings

Both the analytical model and numerical simulations are highly correlated. Results indicated that the analytical model, emphasising material conduction, exhibited exceptional precision, although at substantially reduced cost. Statistical analysis of numerical outcomes underscored the substantial impact of beam power and scan speed on melt pool morphology and temperature in EB-PBF of copper.

Originality/value

This numerical simulation of copper in EB-PBF is the first high-fidelity model to consider the interaction between powder and substrate comprehensively. It accurately captures material properties, powder size distribution, thermal dynamics (including heat transfer between powder and substrate), phase changes and fluid dynamics. The model also integrates advanced computational methods such as computational fluid dynamics and discrete element method. The proposed model and simulation offer a valuable predictive tool for melt pool temperature, heat transfer processes and morphology. These insights are critical for ensuring the bonding quality of subsequent layers and, consequently, influencing the overall quality of the printed parts.

Details

Rapid Prototyping Journal, vol. 31 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 20 June 2017

Shiqing Cao, Dandan Yu, Weilan Xue, Zuoxiang Zeng and Wanyu Zhu

The purpose of this paper is to prepare a new modified polybutylene terephalate (MPBT) for fused deposition modeling (FDM) to increase the variety of materials compatible with…

312

Abstract

Purpose

The purpose of this paper is to prepare a new modified polybutylene terephalate (MPBT) for fused deposition modeling (FDM) to increase the variety of materials compatible with printing. And the printing materials can be used to print components with a complex structure and functional mechanical parts.

Design/methodology/approach

The MPBT, poly(butylene terephalate-co-isophthalate-co-sebacate) (PBTIS), was prepared for FDM by direct esterification and subsequent polycondensation using terephthalic acid (PTA), isophthalic acid (PIA), sebacic acid (SA) and 1,4-butanediol (BDO). The effects of the content of PIA (20-40 mol%) on the mechanical properties of PBTIS were investigated when the mole per cent of SA (αSA) is zero. The effects of αSA (0-7mol%) on the thermal, rheological and mechanical properties of PBTIS were investigated at nPTA/nPIA = 7/3. A desktop wire drawing and extruding machine was used to fabricate the filaments, whose printability and anisotropy were tested by three-dimensional (3D) printing experiments.

Findings

A candidate content of PIA introducing into PBT was obtained to be about 30 per cent, and the Izod notched impact strength of PBTIS increased with the increase of αSA. The results showed that the PBTIS (nPTA/nPIA = 7/3, αSA = 3-5mol%) is suitable for FDM.

Originality/value

New printing materials with good Izod notched impact strength were obtained by introducing PIA and SA (nPTA/nPIA = 7/3, αSA = 3-5 mol%) into PBT and their anisotropy are better than that of ABS.

Details

Rapid Prototyping Journal, vol. 23 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 16 March 2015

David Roberson, Corey M Shemelya, Eric MacDonald and Ryan Wicker

The purpose of this paper is to demonstrate the strategy for increasing the applicability of material extrusion additive manufacturing (AM) technologies, based on fused deposition…

2178

Abstract

Purpose

The purpose of this paper is to demonstrate the strategy for increasing the applicability of material extrusion additive manufacturing (AM) technologies, based on fused deposition modeling (FDM), through the development of materials with targeted physical properties. Here, the authors demonstrate materials specifically developed for the manufacture of electromechanical and electromagnetic applications, the use of FDM-type processes in austere environments and the application of material extrusion AM.

Design/methodology/approach

Using a twin screw polymeric extrusion process, novel polymer matrix composites and blends were created where the base material was a material commonly used in FDM-type processes, namely, acrylonitrile butadiene styrene (ABS) or polycarbonate (PC).

Findings

The work presented here demonstrates that, through targeted materials development, the applicability of AM platforms based on FDM technology can be increased. Here, the authors demonstrate that that the physical properties of ABS and PC can be manipulated to be used in several applications such as electromagnetic and X-ray shielding. Other instances of the development of new materials for FDM led to mitigation of problems associated with the process such as surface finish and mechanical property anisotropy based on build orientation.

Originality/value

This paper is an overview of a research effort dedicated to increasing the amount of material systems available to material extrusion AM. Here materials development is shown to not only increase the number of suitable applications for FDM-type processes, but to be a pathway toward solving inherent problems associated with FDM such as surface finish and build orientation-caused mechanical property anisotropy.

Details

Rapid Prototyping Journal, vol. 21 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 12 January 2022

Xushan Zhao, Yuanxun Wang, Haiou Zhang, Runsheng Li, Xi Chen and Youheng Fu

This paper aims to summarize the influence law of hybrid deposited and micro-rolling (HDMR) technology on the bead morphology and overlapping coefficient. A better bead topology…

319

Abstract

Purpose

This paper aims to summarize the influence law of hybrid deposited and micro-rolling (HDMR) technology on the bead morphology and overlapping coefficient. A better bead topology positively supports the overlapping deposited in multi-beads between layers while actively assisting the subsequent layer's deposition in the wire and arc additive manufacturing (WAAM). Hybrid-deposited and micro-rolling (HDMR) additive manufacturing (AM) technology can smooth the weld bead for improved surface quality. However, the micro-rolling process will change the weld bead profile fitting curve to affect the overlapping coefficient.

Design/methodology/approach

Weld bead contours for WAAM and HDMR were extracted using line lasers. A comparison of bead profile curves was conducted to determine the influence law of micro-zone rolling on the welding bead contour and fitting curve. Aiming at the optimized overlapping coefficient of weld bead in HDMR AM, the optimal HDMR overlapping coefficient curve was proposed which varies with the reduction based on the best surface flatness. The mathematical model for overlapping in HDMR was checked by comparing the HDMR weld bead contours under different rolling reductions.

Findings

A fitting function of the bead forming by HDMR AM was proposed based on the law of conservation of mass. The change rule of the HDMR weld bead overlapping spacing with the degree of weld bead rolling reduction was generated using the flat-top transition calculation for this model. Considering the damming-up impact of the first bead, the overlapping coefficient was examined for its effect on layer surface flatness.

Originality/value

Using the predicted overlapping model, the optimal overlapping coefficients for different rolling reductions can be achieved without experiments. These conclusions can encourage the development of HDMR technology.

Details

Rapid Prototyping Journal, vol. 28 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 17 August 2015

Nicholas A. Meisel and Christopher B. Williams

The purpose of this study/paper is to present the design and implementation of a novel vending machine concept based on desktop-scale extrusion additive manufacturing (AM). Due to…

1324

Abstract

Purpose

The purpose of this study/paper is to present the design and implementation of a novel vending machine concept based on desktop-scale extrusion additive manufacturing (AM). Due to cost, access to AM technologies at academic institutions tends to be limited to upper-level courses to support project-based coursework. However, with the decreasing cost of desktop-scale AM technology, there is potential to improve student access to such technologies and provide more opportunities for AM education.

Design/methodology/approach

The authors present the design and implementation of an AM “vending machine” that is powered by desktop-scale extrusion-based AM systems. This system intends to provide students broad, unrestricted access to entry-level AM tools and promote informal learning opportunities.

Findings

Student users of the AM vending machine are found to be primarily engineering majors at various levels in their studies. Manufactured parts are evenly split between functional and decorative parts, though 75 per cent of students are creating their own designs rather than simply printing found design files.

Research limitations/implications

Future work will focus on improving the system’s ease-of-maintenance, lowering the barrier to entry with a simpler user interface and establishing a method for better recording part and user information.

Practical implications

The interface of the AM vending machine lowers the barrier of entry into engaging with AM and places this emerging technology in a familiar and “safe” context. It provides students at various levels and disciplines the opportunity to fabricate parts for classroom and personal projects.

Social implications

A “vending machine” system may have far-reaching implications for public access and use of AM. Such broad access has the potential to further educate and impassion the public about the potential of AM.

Originality/value

This work represents the creation and assessment of the world’s first AM vending machine.

Details

Rapid Prototyping Journal, vol. 21 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

1 – 10 of 12
Per page
102050