Search results

1 – 10 of over 66000
Article
Publication date: 6 July 2020

Johanna J. Schwartz, Joshua Hamel, Thomas Ekstrom, Leticia Ndagang and Andrew J. Boydston

Additive manufacturing (AM) methods such as material extrusion (ME) are becoming widely used by engineers, designers and hobbyists alike for a wide variety of…

Abstract

Purpose

Additive manufacturing (AM) methods such as material extrusion (ME) are becoming widely used by engineers, designers and hobbyists alike for a wide variety of applications. Successfully manufacturing objects using ME three-dimensional printers can often require numerous iterations to attain predictable performance because the exact mechanical behavior of parts fabricated via additive processes are difficult to predict. One of that factors that contributes to this difficulty is the wide variety of ME feed stock materials currently available in the marketplace. These build materials are often sold based on their base polymer material such as acrylonitrile butadiene styrene or polylactic acid (PLA), but are produced by numerous different commercial suppliers in a wide variety of colors using typically undisclosed additive feed stocks and base polymer formulations. This paper aims to present the results from an experimental study concerned with quantifying how these sources of polymer variability can affect the mechanical behavior of three-dimensional printed objects. Specifically, the set of experiments conducted in this study focused on following: several different colors of PLA filament from a single commercial supplier to explore the effect of color additives and three filaments of the same color but produced by three different suppliers to account for potential variations in polymer formulation.

Design/methodology/approach

A set of five common mechanical and material characterization tests were performed on 11 commercially available PLA filaments in an effort to gain insight into the variations in mechanical response that stem from variances in filament manufacturer, feed stock polymer, additives and processing. Three black PLA filaments were purchased from three different commercial suppliers to consider the variations introduced by use of different feed stock polymers and filament processing by different manufacturers. An additional eight PLA filaments in varying colors were purchased from one of the three suppliers to focus on how color additives lead to property variations. Some tests were performed on unprocessed filament samples, while others were performed on objects three-dimensional printed from the various filaments. This study looked specifically at four mechanical properties (Young’s modulus, storage modulus, yield strength and toughness) as a function of numerous material properties (e.g. additive loading, molecular weight, molecular weight dispersity, enthalpy of melting and crystallinity).

Findings

For the 11 filaments tested the following mean values and standard deviations were observed for the material properties considered: pa = 1.3 ± 0.9% (percent additives), Mw = 98.6 ± 16.4 kDa (molecular weight), Ð = 1.33 ± 0.1 (molecular weight dispersity), Hm = 37.4 ± 7.2 J/g (enthalpy of melting) and = 19.6 ± 2.1% (crystallinity). The corresponding mean values and standard deviations for the resulting mechanical behaviors were: E = 2,790 ± 145 MPa (Young’s modulus), E’ = 1,050 ± 125 MPa (storage modulus), Sy = 49.6 ± 4.93 MPa (yield strength) and Ut = 1.87 ± 0.354 MJ/m^3 (toughness). These variations were observed in filaments that were all manufactured from the same base polymer (e.g. PLA) and are only different in terms of the additives used by the manufacturers to produce different colors or different three-dimensional printing performance. Unfortunately, while the observed variations were significant, no definitive strong correlations were found between these observed variations in the mechanical behavior of the filaments studied and the considered material properties.

Research limitations/implications

These variations in mechanical behavior and material properties could not be ascribed to any specific factor, but rather show that the mechanical of three-dimensional printed parts are potentially affected by variations in base polymer properties, additive usage and filament processing choices in complex ways that can be difficult to predict.

Practical implications

These results emphasize the need to take processing and thereby even filament color, into account when using ME printers, they emphasize the need for designers to use AM with caution when the mechanical behavior of a printed part is critical and they highlight the need for continued research in this important area. While all filaments used were marked as PLA, the feedstock materials, additives and processing conditions created significant differences in the mechanical behavior of the printed objects evaluated, but these differences could not be accurately and reliably predicted as function of the observed material properties that were the focus of this study.

Originality/value

The testing methods used in the study can be used by engineers and creators alike to better analyze the material properties of their filament printed objects, to increase success in print and mechanical design. Furthermore, the results clearly show that as AM continues to evolve and grow as a manufacturing method, standardization of feedstock processing conditions and additives would enable more reliable and repeatable printed objects and would better assist designers in effectively implementing AM methods.

Details

Rapid Prototyping Journal, vol. 26 no. 7
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 11 September 2019

Swapnil Vyavahare, Soham Teraiya, Deepak Panghal and Shailendra Kumar

Fused deposition modelling (FDM) is the most economical additive manufacturing technique. The purpose of this paper is to describe a detailed review of this technique…

2017

Abstract

Purpose

Fused deposition modelling (FDM) is the most economical additive manufacturing technique. The purpose of this paper is to describe a detailed review of this technique. Total 211 research papers published during the past 26 years, that is, from the year 1994 to 2019 are critically reviewed. Based on the literature review, research gaps are identified and the scope for future work is discussed.

Design/methodology/approach

Literature review in the domain of FDM is categorized into five sections – (i) process parameter optimization, (ii) environmental factors affecting the quality of printed parts, (iii) post-production finishing techniques to improve quality of parts, (iv) numerical simulation of process and (iv) recent advances in FDM. Summary of major research work in FDM is presented in tabular form.

Findings

Based on literature review, research gaps are identified and scope of future work in FDM along with roadmap is discussed.

Research limitations/implications

In the present paper, literature related to chemical, electric and magnetic properties of FDM parts made up of various filament feedstock materials is not reviewed.

Originality/value

This is a comprehensive literature review in the domain of FDM focused on identifying the direction for future work to enhance the acceptability of FDM printed parts in industries.

Details

Rapid Prototyping Journal, vol. 26 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 December 2004

George K. Stylios

Examines the tenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects…

2961

Abstract

Examines the tenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.

Details

International Journal of Clothing Science and Technology, vol. 16 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

Article
Publication date: 19 October 2015

Sunil Kumar Tiwari, Sarang Pande, Sanat Agrawal and Santosh M. Bobade

The purpose of this paper is to propose and evaluate the selection of materials for the selective laser sintering (SLS) process, which is used for low-volume production in…

3051

Abstract

Purpose

The purpose of this paper is to propose and evaluate the selection of materials for the selective laser sintering (SLS) process, which is used for low-volume production in the engineering (e.g. light weight machines, architectural modelling, high performance application, manufacturing of fuel cell, etc.), medical and many others (e.g. art and hobbies, etc.) with a keen focus on meeting customer requirements.

Design/methodology/approach

The work starts with understanding the optimal process parameters, an appropriate consolidation mechanism to control microstructure, and selection of appropriate materials satisfying the property requirement for specific application area that leads to optimization of materials.

Findings

Fabricating the parts using optimal process parameters, appropriate consolidation mechanism and selecting the appropriate material considering the property requirement of applications can improve part characteristics, increase acceptability, sustainability, life cycle and reliability of the SLS-fabricated parts.

Originality/value

The newly proposed material selection system based on properties requirement of applications has been proven, especially in cases where non-experts or student need to select SLS process materials according to the property requirement of applications. The selection of materials based on property requirement of application may be used by practitioners from not only the engineering field, medical field and many others like art and hobbies but also academics who wish to select materials of SLS process for different applications.

Details

Rapid Prototyping Journal, vol. 21 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 2 August 2021

Modupeola Dada, Patricia Popoola and Ntombi Mathe

This study aims to review the recent advancements in high entropy alloys (HEAs) called high entropy materials, including high entropy superalloys which are current…

Abstract

Purpose

This study aims to review the recent advancements in high entropy alloys (HEAs) called high entropy materials, including high entropy superalloys which are current potential alternatives to nickel superalloys for gas turbine applications. Understandings of the laser surface modification techniques of the HEA are discussed whilst future recommendations and remedies to manufacturing challenges via laser are outlined.

Design/methodology/approach

Materials used for high-pressure gas turbine engine applications must be able to withstand severe environmentally induced degradation, mechanical, thermal loads and general extreme conditions caused by hot corrosive gases, high-temperature oxidation and stress. Over the years, Nickel-based superalloys with elevated temperature rupture and creep resistance, excellent lifetime expectancy and solution strengthening L12 and γ´ precipitate used for turbine engine applications. However, the superalloy’s density, low creep strength, poor thermal conductivity, difficulty in machining and low fatigue resistance demands the innovation of new advanced materials.

Findings

HEAs is one of the most frequently investigated advanced materials, attributed to their configurational complexity and properties reported to exceed conventional materials. Thus, owing to their characteristic feature of the high entropy effect, several other materials have emerged to become potential solutions for several functional and structural applications in the aerospace industry. In a previous study, research contributions show that defects are associated with conventional manufacturing processes of HEAs; therefore, this study investigates new advances in the laser-based manufacturing and surface modification techniques of HEA.

Research limitations/implications

The AlxCoCrCuFeNi HEA system, particularly the Al0.5CoCrCuFeNi HEA has been extensively studied, attributed to its mechanical and physical properties exceeding that of pure metals for aerospace turbine engine applications and the advances in the fabrication and surface modification processes of the alloy was outlined to show the latest developments focusing only on laser-based manufacturing processing due to its many advantages.

Originality/value

It is evident that high entropy materials are a potential innovative alternative to conventional superalloys for turbine engine applications via laser additive manufacturing.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 18 February 2021

Ana C. Lopes, Álvaro M. Sampaio, Cátia S. Silva and António J. Pontes

Owing to the operating principle of powder bed fusion processes, selective laser sintering (SLS) requires effective management of the mixture ratio of processed material

Abstract

Purpose

Owing to the operating principle of powder bed fusion processes, selective laser sintering (SLS) requires effective management of the mixture ratio of processed material previously exposed to the high temperatures of processing with new virgin material. Therefore, this paper aims to fully understand the effect that the successive reprocessing has in the powder material and to evaluate its influence on the properties of SLS parts produced at different building orientations.

Design/methodology/approach

Polyamide 12 material with 0%, 30% and 50% of virgin powder and parts produced from them were studied through five consecutive building cycles and their mass, mechanical, thermal and microstructural properties were evaluated. Then, the experimental data was used to validate a theoretical algorithm of prediction capable to define the minimum amount of virgin powder to be added on the processed material to produce parts without significant loss of properties.

Findings

Material degradation during SLS influences the mass and mechanical properties of the parts, exhibiting an exponential decay property loss until 50% of the initial values. The theoretical algorithms of reprocessing proved the appropriateness to use a mixture of 30% of virgin with 70% of processed material for the most common purposes.

Practical implications

This paper validates a methodology to define the minimum amount of virgin material capable to fulfil the operational specifications of SLS parts as a function of the number of building cycles, depending on the requirements of the final application.

Originality/value

The use of theoretical models of prediction allows to describe the degradation effects of SLS materials during the sintering, ensuring the sustainable management of the processed powder and the economic viability of the process.

Details

Rapid Prototyping Journal, vol. 27 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 16 October 2018

Guotao Zhang, Yanguo Yin, Ming Xu and Congmin Li

This paper aims to obtain high mechanical strength and good self-lubricating property of iron-based powder metallurgy materials. A new type of bilayer material with dense…

Abstract

Purpose

This paper aims to obtain high mechanical strength and good self-lubricating property of iron-based powder metallurgy materials. A new type of bilayer material with dense substrate and porous surface was proposed in this paper to obtain high strength and good self-lubricating property.

Design/methodology/approach

The materials were prepared by powder metallurgy. Their friction and wear properties were investigated with an end-face tribo-tester. Energy dispersive spectrometer, X-ray diffraction and the 3D laser scanning technologies were used to characterise the tribological properties of materials. The tribological and bearing mechanisms of the monolayer and bilayer materials were compared.

Findings

The results show that adding proper TiH2 can effectively improve the porosity and hardness. With the TiH2 content increased from 0 to 4 per cent, the average friction coefficients increase slowly, and the wearability decreases first and then increases. When containing 3.5 per cent TiH2, high strength and good self-lubrication characteristics are obtained. Besides, the tribological properties of monolayer materials are better than those of bilayer materials when the load is between 980 and 1,470 N, while the opposite result is obtained under the load varied from 1,470 to 2,450 N. In the bilayer material, the porous oil surface can lubricate well and the dense substrate can improve the mechanical property. So, its comprehensive tribological and mechanical properties are better than those of monolayer material.

Originality/value

The friction and wear properties of a new type bilayer materials were investigated. And their tribological mechanisms were proposed. This work can provide a theoretical reference for developing high-performance iron-based oil materials under boundary lubrication.

Details

Industrial Lubrication and Tribology, vol. 70 no. 9
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 13 November 2009

George K. Stylios

Examines the fifthteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched…

Abstract

Examines the fifthteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.

Details

International Journal of Clothing Science and Technology, vol. 21 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

Article
Publication date: 14 June 2011

William Cooke, Rachel Anne Tomlinson, Richard Burguete, Daniel Johns and Gaëlle Vanard

The purpose of this paper is to rigorously determine the tensile properties of a selective laser sintering (SLS) material. Emphasis was placed on the anisotropy and…

1225

Abstract

Purpose

The purpose of this paper is to rigorously determine the tensile properties of a selective laser sintering (SLS) material. Emphasis was placed on the anisotropy and inhomogeneity of the material, the repeatability of the SLS process, and the effect of age (actually moisture absorption) on the material properties.

Design/methodology/approach

Two builds of 144 dogbone tensile specimens each were tested, with 18 specimens stored for 43 days in a non‐desiccated environment before testing. Specimens were distributed throughout the build volume and aligned with the apparatus' principal axes. Tensile properties were treated statistically, using the t‐test to determine the differences between various samples.

Findings

The material was transversely isotropic in Young's modulus and strain to failure, and generally orthotropic in ultimate tensile strength. The material was inhomogeneous throughout the build volume and affected by age, with a 57 per cent reduction in University of Technology after 43 days (the changes in properties were suggested to be due to moisture absorption). Properties varied by up to 25 per cent from build‐to‐build with no change in nominal process parameters.

Research limitations/implications

It was not possible to confirm the “ageing” effect was caused by moisture absorption, and further work is suggested in this area. The causes of inhomogeneity and the effect of re‐coater action should also be studied further.

Originality/value

This is the most complete study of an SLS material's mechanical properties to date. The statistical analyses used further allow increased confidence in the conclusions drawn. This is also the only study to use cross‐fill scanning to produce specimens, and, therefore, isolate the effect of the re‐coater action.

Details

Rapid Prototyping Journal, vol. 17 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 20 November 2007

George K. Stylios

Examines the thirteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched…

1363

Abstract

Examines the thirteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.

Details

International Journal of Clothing Science and Technology, vol. 19 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

1 – 10 of over 66000