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Article
Publication date: 2 August 2011

A.B. Spierings, M. Schneider and R. Eggenberger

In the optimisation of processing parameters for additive manufactured parts using, e.g. selective laser melting (SLM) or electron beam melting, the measurement of the…

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Abstract

Purpose

In the optimisation of processing parameters for additive manufactured parts using, e.g. selective laser melting (SLM) or electron beam melting, the measurement of the part densities is essential and of high interest. However, there is no common standard. Different institutes and system providers are using their own principles and guidelines. This study investigates the accuracies of the three measurement principles: Archimedes method, microscopic analysis of cross sections and X‐ray scanning.

Design/methodology/approach

A total of 15 test samples on five density levels (densities between 90 and 99.5 per cent) were produced using the SLM process. The samples are analysed regarding the accuracy of the measurement principles and their reproducibility taking into account influencing parameters like the buoyancy of a sample in air (Archimedes method) or different magnifications of a cross section.

Findings

The Archimedes method shows a very high accuracy (±0.08 per cent for high densities) and repeatability (±<0.1 per cent) on all density levels. In contrast to the Archimedes method, taking a micrograph of a specific cross section allows to influence the resulting density and the coefficient of variation reaches values>4 per cent. However, for low porosities, mean densities are comparable to the results of the Archimedes method even though calculated densities are typically somewhat too high. The advantage of the image guided analysis (2D and 3D) is getting more information about the distribution, size and form of pores in the part.

Originality/value

The findings do not only refer to metallic parts but generally to all parts having a specific porosity. The study is a contribution to the American Society for Testing and Materials initiative F42 “Additive Manufacturing Technology” and especially to the subcommittee “test methods”.

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Rapid Prototyping Journal, vol. 17 no. 5
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 June 2012

Wenfang Song, Qian Liu and Weidong Yu

The purpose of this paper is to describe a new apparatus for testing acoustic insulating, air permeating and water vapor transfer properties of fibrous assemblies with…

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194

Abstract

Purpose

The purpose of this paper is to describe a new apparatus for testing acoustic insulating, air permeating and water vapor transfer properties of fibrous assemblies with density variation.

Design/methodology/approach

An apparatus is designed and built in order to investigate the acoustic insulating, air permeating and water vapor transfer properties of fiber assemblies with density variation. The apparatus mainly consists of three chambers, just like the structure of a syringe. The three properties can be measured by placing different sensors at the corresponding chambers. The material density variation can be realized by compression.

Findings

The new apparatus can realize the measurement of the three properties with density variation, which provides a new perspective to study the physical property of fibrous assemblies.

Originality/value

The paper introduces a new apparatus for testing acoustic insulating, air permeating and water vapor transfer properties of fibrous assemblies with density variation.

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Article
Publication date: 1 August 2001

Erwan Collet, Bernard Delores, Michel Gabillard and Isabelle Ragault

Shows how observations (1993‐1999) and on‐site and laboratory measurements (1993‐1996) have made it possible to define certain prevalent parameters concerning AC corrosion…

Abstract

Shows how observations (1993‐1999) and on‐site and laboratory measurements (1993‐1996) have made it possible to define certain prevalent parameters concerning AC corrosion risks. These are from the evaluation and prevention of AC corrosion risks as practised by Gaz de France.

Details

Anti-Corrosion Methods and Materials, vol. 48 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 29 June 2010

K. Bukat, Z. Moser, J. Sitek, W. Gąsior, M. Kościelski and J. Pstruś

The purpose of Part I of this paper is to investigate the influence of Bi additions on the surface tension, the interfacial tension, and the density of SnZn7Bi alloys…

Abstract

Purpose

The purpose of Part I of this paper is to investigate the influence of Bi additions on the surface tension, the interfacial tension, and the density of SnZn7Bi alloys (Bi=1 and 3 percent by mass) as a continuation of similar previous studies on Bi and Sb additions to the binary Sn‐Zn alloy. The main aim of Part I is to indicate that the lowering of the surface tension and interfacial tension is not sufficient for practical applications. However, knowledge of the interfacial tension between the soldering flux and the solder is necessary to convert the wetting force into the contact angle. This will be documented in Part II.

Design/methodology/approach

The maximum bubble method was applied for the surface tension and the Miyazaki method was applied for the surface tension and the interfacial tension, using the density values from the dilatometric technique. The experimental surface tension results are compared with the Butler's thermodynamic modeling results and are discussed by means of the analysis of variance (ANOVA).

Findings

On the basis of previous studies on Sn‐Zn‐Bi‐Sb alloys, the addition of Bi to SnZn7 slightly decreased the surface tension measured in an Ar+H2 atmosphere, similarly to the Butler's modeling results. Also, a similar slight decrease of the surface tension from the Miyazaki method measured in air and in nitrogen was observed, as well as a more significant lowering of the interfacial tension with the use of a flux in nitrogen. There was also a slight influence of the temperature on the numerical values of the surface tensions and the interfacial tension. In the ANOVA, taking into account the Bi content, the temperature of measurements, the atmosphere and the flux, the flux used was shown as the most important, and also, to a lesser extent, the atmosphere.

Research limitations/implications

It is intended (the purpose of Part II of this paper) to verify the positive influence of Bi additions in SnZn7 alloys on the surface tensions and the interfacial tensions via the contact angles from the interaction with Cu on printed circuit board with different lead‐free finishes.

Practical implications

It is suggested that further studies on more efficient fluxes are necessary for the practical application being in agreement with the ANOVA and the literature information.

Originality/value

A slight improvement of the wettability with the use of Bi additions in the SnZn7Bi alloys in the course of various experimental techniques is proven, similar to results reported in various references. The obtained results will enlarge the SURDAT database of lead‐free soldering materials.

Details

Soldering & Surface Mount Technology, vol. 22 no. 3
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 July 2006

R. Schmidt, G. Klingenberg and M. Woydt

The use of alternative oils for the lubrication of automobile engines has a potential of ecological and technical advantages. It requires the detailed knowledge of several…

Abstract

Purpose

The use of alternative oils for the lubrication of automobile engines has a potential of ecological and technical advantages. It requires the detailed knowledge of several thermophysical and viscosimetric properties in a large temperature range.

Design/methodology/approach

For 11 different oils, the density, the heat capacity, the thermal conductivity, the viscosity at ambient pressure and the pressure‐viscosity at maximal 1,000 bar have been measured. The latter has been measured with a newly developed apparatus which is described in detail. Two hydrocarbon‐based factory‐fill oils and nine alternative oils have been tested. Five of the alternative oils are based partly or completely on esters, the other four on polyglycols, one of them additionally on water.

Findings

Data for thermophysical and viscosimetric properties are given in form of diagrams and tables. The consequences for the cooling capacity and the film forming behavior are discussed. The latter is only slightly better for the factory‐fill oils, compared to the alternative oils.

Research limitations/implications

The pressure‐viscosity is measured at up to 1,000 bar, which is lower than the maximum pressure in the tribological contacts of an engine.

Practical implications

The published data can be used to calculate tribological contacts which are lubricated with alternative engine oils or with actually used factory‐fill oils. This might help to decide if esters or polyglycols are superior as engine oils.

Originality/value

The results of this test program might be helpful for engineers who are interested in using alternative lubricants in tribosystems.

Details

Industrial Lubrication and Tribology, vol. 58 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 18 April 2016

Jan Patrick Deckers, Khuram Shahzad, Ludwig Cardon, Marleen Rombouts, Jozef Vleugels and Jean-Pierre Kruth

The purpose of this paper is to compare different powder metallurgy (PM) processes to produce ceramic parts through additive manufacturing (AM). This creates the potential…

Abstract

Purpose

The purpose of this paper is to compare different powder metallurgy (PM) processes to produce ceramic parts through additive manufacturing (AM). This creates the potential to rapidly shape ceramic parts with an almost unlimited shape freedom. In this paper, alumina (Al2O3) parts are produced, as Al2O3 is currently the most commonly used ceramic material for technical applications.

Design/methodology/approach

Variants of the following PM route, with indirect selective laser sintering (indirect SLS) as the AM shaping step, are explored to produce ceramic parts: powder synthesis, indirect SLS, binder removal and furnace sintering and alternative densification steps.

Findings

Freeform-shaped Al2O3 parts with densities up to approximately 90 per cent are obtained.

Research limitations/implications

The resulting Al2O3 parts contain inter-agglomerate pores. To produce higher-quality ceramic parts through indirect SLS, these pores should be avoided or eliminated.

Originality/value

The research is innovative in many ways. First, composite powders are produced using different powder production methods, such as temperature-induced phase separation and dispersion polymerization. Second, four different binder materials are investigated: polyamide (nylon-12), polystyrene, polypropylene and a carnauba wax – low-density polyethylene combination. Further, to produce ceramic parts with increased density, the following densification techniques are investigated as additional steps of the PM process: laser remelting, isostatic pressing and infiltration.

Details

Rapid Prototyping Journal, vol. 22 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 19 October 2015

Christina Blümel, Marius Sachs, Tobias Laumer, Bettina Winzer, Jochen Schmidt, Michael Schmidt, Wolfgang Peukert and Karl-Ernst Wirth

The purpose of this paper is to demonstrate the processability of cohesive PE-HD particles in laser beam melting processes (LBM) of polymers. Furthermore, we present a…

Abstract

Purpose

The purpose of this paper is to demonstrate the processability of cohesive PE-HD particles in laser beam melting processes (LBM) of polymers. Furthermore, we present a characterization method for polymer particles, which can predict the quality of the powder deposition via LBM processes.

Design/methodology/approach

This study focuses on the application of dry particle coating processes to increase flowability and bulk density of PE-HD particles. Both has been measured and afterwards validated via powder deposition of PE-HD particles in a LBM machine.

Findings

For efficient coating in a dry particle coating process, the PE-HD particles and the attached nanoparticles need to show similar surface chemistry, i.e. both need to behave either hydrophobic or hydrophilic. It is demonstrated that dry particle coating is appropriate to enhance flowability and bulk density of PE-HD particles and hence considerably improves LBM processes and the resulting product quality.

Originality/value

At present, in LBM processes mainly polyamide (PA), 12 particles are used, which are so far quite expensive in comparison to, for example, PE-HD particles. This work provides a unique and versatile method for nanoparticulate surface modification which may be applied to a wide variety of materials. After the coating, the particles are applicable for the LBM process. Our results provide a correlation between flowability and bulk density and the resulting product quality.

Details

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

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Article
Publication date: 1 December 1982

M.A. Rabah, A.A. Aboukhashaba and M.S. Aly

The European association of pigment and dye manufacturers established a method for the estimation of heat and light fastness of organic pigments. In such method, pigments…

Abstract

The European association of pigment and dye manufacturers established a method for the estimation of heat and light fastness of organic pigments. In such method, pigments were dispersed in partially dried linseed oil whereby prints were made on standard writing paper. Degraded prints were visually estimated after comparing with a freshly prepared standard scale of 8 grades. A sample similar to scale 5 or more was considered to be of good or excellent fastness. Practically, it became familiar with controversial personnel estimations, especially in regard to the critical level of 4–5. Furthermore, the specific side effect interference of the linseed oil resin could not be avoided. It becomes reasonable to put forward a method depending on instrumental measurements. In the light of this method, heat and light fastness of organic pigments can be colourimetrically determined. The pigment is pasted in water containing 2–3% weight of sodium silicate as binding agent. Thin film prints are then made on a transparent non‐porous standard paper 80 g/m2. Prints are dried over P2O5 in a desicator placed in a cool and dark place. The dried prints are striped in 2cm width. Some of these stripes are taken for the colourimetric determination of the colour density with the help of a colour densitometer. Other stripes are subjected for 72 hours to daylight (not to direct sun rays) or placed in a drying oven maintained at the required temperature for the same duration. For colour density measurements, prints are underlined with 100 g/m2 white standard paper. Peak heights obtained with certain light wave‐length are computed with reference to the peak of the undergraded sample. It has been shown that a change in heat or light fastness as low as 2% can be determined with an accuracy range of 0.5% compared to 12.5% and 3.5% for the European method respectively.

Details

Pigment & Resin Technology, vol. 11 no. 12
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 22 August 2017

Nataliya Perevoshchikova, Jordan Rigaud, Yu Sha, Martin Heilmaier, Barrie Finnin, Elena Labelle and Xinhua Wu

The Ni-based superalloy IN-738 LC is known to be susceptible to porosity and different types of cracking during the build-up process and, thus, challenging to manufacture…

Abstract

Purpose

The Ni-based superalloy IN-738 LC is known to be susceptible to porosity and different types of cracking during the build-up process and, thus, challenging to manufacture using selective laser melting (SLM). Determining a feasible set of operating parameters for SLM of nickel-based superalloys involves new approach to experimental design based on the Doehlert method that assists in determining an optimal (feasible) set of operating parameters for SLM of IN-738 LC powder alloy.

Design/methodology/approach

The SLM parameters are evaluated in terms of their effectiveness in obtaining the microstructure with a porosity content of <0.5 per cent and without micro-cracking. The experimental approach is exemplified with the Doehlert matrix response variable, relative density, by comparing Archimedes method with microstructural assessments of pores and cracks from image analysis. The effect of heat treatment (HT) and hot isostatic pressing (HIP) on the microstructure of the SLMed IN-738 LC powder alloy has been examined and the consequential tensile response characterised.

Findings

By using optimised process parameters (low heat input, medium scanning speed and small hatching distance) which provides medium energy density, samples of IN-738 LC with a macroscopic porosity <0.5 per cent and free of micro-cracks can be manufactured by SLM. The results indicate that HIP of SLMed material did not lead to a noticeable effect on mechanical properties compared to HT of SLMed material suggesting that the level of both porosity and crack density might be already below the detection limit for the mere heat-treated material.

Originality/value

SLM processing parameters (power, scan speed, hatching distance) for IN-738 LC were successfully optimised after only 14 experiments using Doehlert design. Two independent methods, Archimedes method and image analysis, were used in this study to assess relative density of SLM-produced samples with sets of processing parameters showing coherency in prediction with predicted response by Doehlert design.

Details

Rapid Prototyping Journal, vol. 23 no. 5
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 17 October 2017

Karl P. Davidson and Sarat B. Singamneni

This paper aims to establish the microstructures and the process-structure relationships in duplex stainless steel powders consolidated by selective laser melting (SLM).

Abstract

Purpose

This paper aims to establish the microstructures and the process-structure relationships in duplex stainless steel powders consolidated by selective laser melting (SLM).

Design/methodology/approach

A priori data on energy density levels most appropriate to consolidation of duplex stainless steel powders through SLM served as the basis to converge on the laser settings. Experimental designs with varying laser power and scan speeds and test pieces generated allowed metallographic evaluations based on optical and scanning electron microscopy and electro backscatter diffraction analyses.

Findings

Duplex stainless steel powders are established for processing by SLM. However, the dynamic point heat source and associated transient thermal fields affect the microstructures to be predominantly ferritic, with grains elongated in the build direction. Austenite precipitated either at the grain boundaries or as Widmanstätten laths, whereas the crystallographic orientations and the grain growth are affected around the cavities. Considerable CrN precipitation is also evidenced.

Originality/value

Duplex stainless steels are relatively new candidates to be brought into the additive manufacturing realm. Considering the poor machinability and other difficulties, the overarching result indicating suitability of duplex powders by SLM is of considerable value to the industry. More significantly, the metallographic evaluation and results of the current research allowed further understanding of the material consolidation aspects and pave ways for fine tuning and establishment of the process-structure-property relationships for this important process-material combination.

Details

Rapid Prototyping Journal, vol. 23 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

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