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Article
Publication date: 15 August 2019

Vincent Hammond, Michael Schuch and Matthias Bleckmann

The purpose of this paper is to investigate the influence of a process interruption on the tensile properties of AlSi10Mg samples produced by selective laser melting (SLM).

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Abstract

Purpose

The purpose of this paper is to investigate the influence of a process interruption on the tensile properties of AlSi10Mg samples produced by selective laser melting (SLM).

Design/methodology/approach

Using identical processing parameters, cylindrical samples were produced in either a continuous or interrupted SLM build operation. The tensile properties and microstructure of the samples were determined as a function of process type as well as orientation.

Findings

All samples produced in this paper displayed superior tensile properties to those produced in high pressure die casting. In general, the samples produced in the continuous build process had higher strengths and microhardness than those produced in the interrupted process. However, while most samples displayed random failure locations, the vertical samples produced in the interrupted build process showed a strong tendency for localized failure in the vicinity of the stoppage plane.

Originality/value

This paper demonstrated that samples produced in an interrupted build process tend to have poorer mechanical properties than those produced in a continuous process. Together, these observations highlight the importance of a suitable technique for restarting and completing an interrupted build process to ensure the production of high quality components.

Details

Rapid Prototyping Journal, vol. 25 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 2 February 2023

Mahyar Khorasani, Ian Gibson, Amir Hossein Ghasemi, Elahe Hadavi and Bernard Rolfe

The purpose of this study is, to compare laser-based additive manufacturing and subtractive methods. Laser-based manufacturing is a widely used, noncontact, advanced manufacturing…

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Abstract

Purpose

The purpose of this study is, to compare laser-based additive manufacturing and subtractive methods. Laser-based manufacturing is a widely used, noncontact, advanced manufacturing technique, which can be applied to a very wide range of materials, with particular emphasis on metals. In this paper, the governing principles of both laser-based subtractive of metals (LB-SM) and laser-based powder bed fusion (LB-PBF) of metallic materials are discussed and evaluated in terms of performance and capabilities. Using the principles of both laser-based methods, some new potential hybrid additive manufacturing options are discussed.

Design methodology approach

Production characteristics, such as surface quality, dimensional accuracy, material range, mechanical properties and applications, are reviewed and discussed. The process parameters for both LB-PBF and LB-SM were identified, and different factors that caused defects in both processes are explored. Advantages, disadvantages and limitations are explained and analyzed to shed light on the process selection for both additive and subtractive processes.

Findings

The performance of subtractive and additive processes is highly related to the material properties, such as diffusivity, reflectivity, thermal conductivity as well as laser parameters. LB-PBF has more influential factors affecting the quality of produced parts and is a more complex process. Both LB-SM and LB-PBF are flexible manufacturing methods that can be applied to a wide range of materials; however, they both suffer from low energy efficiency and production rate. These may be useful when producing highly innovative parts detailed, hollow products, such as medical implants.

Originality value

This paper reviews the literature for both LB-PBF and LB-SM; nevertheless, the main contributions of this paper are twofold. To the best of the authors’ knowledge, this paper is one of the first to discuss the effect of the production process (both additive and subtractive) on the quality of the produced components. Also, some options for the hybrid capability of both LB-PBF and LB-SM are suggested to produce complex components with the desired macro- and microscale features.

Details

Rapid Prototyping Journal, vol. 29 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 20 October 2014

Manickavasagam Krishnan, Eleonora Atzeni, Riccardo Canali, Flaviana Calignano, Diego Manfredi, Elisa Paola Ambrosio and Luca Iuliano

The aim of this research is to reach a deep understanding on the effect of the process parameters of Direct Metal Laser Sintering process (DMLS) on macroscopic properties…

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Abstract

Purpose

The aim of this research is to reach a deep understanding on the effect of the process parameters of Direct Metal Laser Sintering process (DMLS) on macroscopic properties (hardness and density) of AlSi10Mg parts and resulting microstructure.

Design/methodology/approach

A full factorial design of experiment (DOE) was applied to determine the most significant process parameter influencing macroscopic properties of AlSi10Mg parts manufactured by DMLS process. The analysis aims to define the optimum process parameters and deduce the process window that provides better macroscopic properties of AlSi10Mg parts. Optical microscopy observations are carried out to link the microstructure to macroscopic properties.

Findings

Macroscopic properties of DMLS parts are influenced by the change in process parameters. There is a close correlation between the geometry of scan tracks and macroscopic properties of AlSi10Mg parts manufactured by DMLS process.

Originality/value

The knowledge of utilizing optimized process parameters is important to fabricate DMLS parts with better mechanical properties. The present research based on applying experimental design is the first analysis for AlSi10Mg parts produced in DMLS process.

Details

Rapid Prototyping Journal, vol. 20 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 3 February 2023

Arad Azizi, Fatemeh Hejripour, Jacob A. Goodman, Piyush A. Kulkarni, Xiaobo Chen, Guangwen Zhou and Scott N. Schiffres

AlSi10Mg alloy is commonly used in laser powder bed fusion due to its printability, relatively high thermal conductivity, low density and good mechanical properties. However, the…

Abstract

Purpose

AlSi10Mg alloy is commonly used in laser powder bed fusion due to its printability, relatively high thermal conductivity, low density and good mechanical properties. However, the thermal conductivity of as-built materials as a function of processing (energy density, laser power, laser scanning speed, support structure) and build orientation, are not well explored in the literature. This study aims to elucidate the relationship between processing, microstructure, and thermal conductivity.

Design/methodology/approach

The thermal conductivity of laser powder bed fusion (L-PBF) AlSi10Mg samples are investigated by the flash diffusivity and frequency domain thermoreflectance (FDTR) techniques. Thermal conductivities are linked to the microstructure of L-PBF AlSi10Mg, which changes with processing conditions. The through-plane exceeded the in-plane thermal conductivity for all energy densities. A co-located thermal conductivity map by frequency domain thermoreflectance (FDTR) and crystallographic grain orientation map by electron backscattered diffraction (EBSD) was used to investigate the effect of microstructure on thermal conductivity.

Findings

The highest through-plane thermal conductivity (136 ± 2 W/m-K) was achieved at 59 J/mm3 and exceeded the values reported previously. The in-plane thermal conductivity peaked at 117 ± 2 W/m-K at 50 J/mm3. The trend of thermal conductivity reducing with energy density at similar porosity was primarily due to the reduced grain size producing more Al-Si interfaces that pose thermal resistance. At these interfaces, thermal energy must convert from electrons in the aluminum to phonons in the silicon. The co-located thermal conductivity and crystallographic grain orientation maps confirmed that larger colonies of columnar grains have higher thermal conductivity compared to smaller columnar grains.

Practical implications

The thermal properties of AlSi10Mg are crucial to heat transfer applications including additively manufactured heatsinks, cold plates, vapor chambers, heat pipes, enclosures and heat exchangers. Additionally, thermal-based nondestructive testing methods require these properties for applications such as defect detection and simulation of L-PBF processes. Industrial standards for L-PBF processes and components can use the data for thermal applications.

Originality/value

To the best of the authors’ knowledge, this paper is the first to make coupled thermal conductivity maps that were matched to microstructure for L-PBF AlSi10Mg aluminum alloy. This was achieved by a unique in-house thermal conductivity mapping setup and relating the data to local SEM EBSD maps. This provides the first conclusive proof that larger grain sizes can achieve higher thermal conductivity for this processing method and material system. This study also shows that control of the solidification can result in higher thermal conductivity. It was also the first to find that the build substrate (with or without support) has a large effect on thermal conductivity.

Article
Publication date: 19 April 2022

Gürkan Tarakçı, Hamaid Mahmood Khan, Mustafa Safa Yılmaz and Gökhan Özer

The present paper aims to systematically investigate the influence of building orientations (0°, 15°, 30°, 45°, 60°, 75°) and heat treatment processes on the…

Abstract

Purpose

The present paper aims to systematically investigate the influence of building orientations (0°, 15°, 30°, 45°, 60°, 75°) and heat treatment processes on the macro-/micro-structural, mechanical and electrochemical behaviors of selective laser melting (SLM) prepared AlSi10Mg alloy parts.

Design/methodology/approach

AlSi10Mg samples were produced by the SLM method using standard processing parameters at 0°, 15°, 30°, 45°, 60° and 75° building angles. The effects of building orientations on the physical, mechanical and electrochemical properties of the alloy were investigated.

Findings

With the increase in the building orientation from 15° to 75°, the structural defects were found reducing. The effect of step size of inclined geometries was found to significantly influence the mechanical and electrochemical properties of the AlSi10Mg samples. Tensile strength for samples fabricated at lower angles (0°, 15°, 30°) reported a drop of approximately 11% than SLM 0° samples. Moreover, the tensile strength was found to decrease from 412.35 ± 9.568 MPa for the as-built samples to 290.48 ± 12.658 MPa, whereas the fracture strain increases from 3.32 ± 0.56% to 5.6 ± 0.6% when the as-built sample was treated with T6 treatment. This study indicates that the microstructure and mechanical properties of SLM-processed AlSi10Mg alloy can be tailored by a suitable heat treatment or building angle.

Originality/value

Microstructural and mechanical behavior of horizontal or vertically built SLM components have already been demonstrated several times. However, the influence of different building orientations, such as 0°, 15°, 30°, 45°, 60°, 75°, has not been explored in-depth, particularly on corrosion and general mechanical performance. As a result, this work may be of significant relevance to academics and designers, given the varying orientation of internal component of SLM structures.

Article
Publication date: 28 January 2014

Ibrahim Elbeltagi, Thijs Kempen and Elaine Garcia

This research covers a rather unexplored area of customer relationship management (CRM) by questioning the mechanism between on the one hand the Pareto-principle and on the other…

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Abstract

Purpose

This research covers a rather unexplored area of customer relationship management (CRM) by questioning the mechanism between on the one hand the Pareto-principle and on the other hand traditional non-IT supported operational CRM processes. Thus, the paper aims to explore whether a minority of processes and process-aspects deserves credit for achieving a majority of CRM goals.

Design/methodology/approach

A qualitative approach is the most appropriate due to the assumption that access to the reality of a situation is only possible through social construction. A qualitative approach seeks to answer questions posed by studying different social settings. As noted by Berg, qualitative techniques make it possible for researchers to participate in understanding and perceiving others, as well as permitting them to discover how people structure their daily lives to make them more meaningful.

Findings

The questioned mechanism of on the one hand traditional non-IT supported operational CRM process-aspects and on the other hand the Pareto-principle is confirmed by the majority of interviewees who answered affirmatively to small things making big differences in customer contact.

Research limitations/implications

Regarding the limitations of this study, the results are hard to generalise as the research context depends on a single case study. However, the high levels of detail that allows for greater insight into manufacturing SMEs in HGV-Trailer that want to adopt non-IT support operational CRM where there is lack of financial resources justify the choice of this case study.

Practical implications

This study is important for management to focus and develop social on top of technical competencies. This was clear from the importance of social intercourse as the glue that links all the non-IT supported operational processes from break down to invoices. It helps in removing the uncertainty from the view point of customers and highlights the importance of the care that companies need to give to the human side of the process more than objectifying things. Moreover, the finding provides an important implication for practitioners involved spare-parts purchasing process and the warranty claiming process should continuously assess whether they operate in support of a breakdown or not and subsequently use this insight to prioritize their tasks.

Originality/value

This research tried to answer how the Pareto-principle applies to traditional non-IT supported operational CRM process-aspects by concluding that the first social intercourse, as well as problem ownership, belongs – from a customers' viewpoint – to the “vital few” leading to “trivial many” results of rational and emotional nature. This is especially true in the breakdown process, and processes that operate in support of breakdowns.

Article
Publication date: 20 March 2017

Il Hyuk Ahn, Seung Ki Moon, Jihong Hwang and Guijun Bi

This paper aims to propose methods to evaluate the characteristic length of the melt pool for accurate fabrication and to identify the optimal process parameters in the selective…

Abstract

Purpose

This paper aims to propose methods to evaluate the characteristic length of the melt pool for accurate fabrication and to identify the optimal process parameters in the selective laser melting process.

Design/methodology/approach

Specimens with the types of the scans by controlling the degree of the overlap with hatch spacing are fabricated. The scan modes are classified by statistically analyzing the results of hardness tests. According to the classification of the scans, the evaluation methods are proposed based on the observation of the shape of the solidified melt pool.

Findings

The control of the hatch spacing can reproduce all modes of the scan conditions, and hardness can be used to classify the scan modes.

Originality/value

The proposed evaluation methods are based on the analysis of the experimental observation so that they can be easily used for the real evaluation.

Details

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

Keywords

Article
Publication date: 2 January 2018

Zhonghua Li, Ibrahim Kucukkoc, David Z. Zhang and Fei Liu

Surface roughness is an important evaluation index for industrial components, and it strongly depends on the processing parameters for selective laser molten Ti6Al4V parts. This…

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Abstract

Purpose

Surface roughness is an important evaluation index for industrial components, and it strongly depends on the processing parameters for selective laser molten Ti6Al4V parts. This paper aims to obtain an optimum selective laser melting (SLM) parameter set to improve the surface roughness of Ti6Al4V samples.

Design/methodology/approach

A response surface methodology (RSM)-based approach is proposed to improve the surface quality of selective laser molten Ti6Al4V parts and understand the relationship between the SLM process parameters and the surface roughness. The main SLM parameters (i.e. laser power, scan speed and hatch spacing) are optimized, and Ti6Al4V parts are manufactured by the SLM technology with no post processes.

Findings

Optimum process parameters were obtained using the RSM method to minimise the roughness of the top and vertical side surfaces. Obtained parameter sets were evaluated based on their productivity and surface quality performance. The validation tests have been performed, and the results verified the effectivity of the proposed technique. It was also shown that the top and vertical sides must be handled together to obtain better top surface quality.

Practical implications

The obtained optimum SLM parameter set can be used in the manufacturing of Ti6Al4V components with high surface roughness requirement.

Originality/value

RSM is used to analyse and determine the optimal combination of SLM parameters with the aim of improving the surface roughness quality of Ti6Al4V components, for the first time in the literature. Also, this is the first study which aims to simultaneously optimise the surface quality of top and vertical sides of titanium alloys.

Details

Rapid Prototyping Journal, vol. 24 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 23 August 2021

Iván La Fé-Perdomo, Jorge Andres Ramos-Grez, Gerardo Beruvides and Rafael Alberto Mujica

The purpose of this paper is to outline some key aspects such as material systems used, phenomenological and statistical process modeling, techniques applied to monitor the…

Abstract

Purpose

The purpose of this paper is to outline some key aspects such as material systems used, phenomenological and statistical process modeling, techniques applied to monitor the process and optimization approaches reported. All these need to be taken into account for the ongoing development of the SLM technique, particularly in health care applications. The outcomes from this review allow not only to summarize the main features of the process but also to collect a considerable amount of investigation effort so far achieved by the researcher community.

Design/methodology/approach

This paper reviews four significant areas of the selective laser melting (SLM) process of metallic systems within the scope of medical devices as follows: established and novel materials used, process modeling, process tracking and quality evaluation, and finally, the attempts for optimizing some process features such as surface roughness, porosity and mechanical properties. All the consulted literature has been highly detailed and discussed to understand the current and existing research gaps.

Findings

With this review, there is a prevailing need for further investigation on copper alloys, particularly when conformal cooling, antibacterial and antiviral properties are sought after. Moreover, artificial intelligence techniques for modeling and optimizing the SLM process parameters are still at a poor application level in this field. Furthermore, plenty of research work needs to be done to improve the existent online monitoring techniques.

Research limitations/implications

This review is limited only to the materials, models, monitoring methods, and optimization approaches reported on the SLM process for metallic systems, particularly those found in the health care arena.

Practical implications

SLM is a widely used metal additive manufacturing process due to the possibility of elaborating complex and customized tridimensional parts or components. It is corroborated that SLM produces minimal amounts of waste and enables optimal designs that allow considerable environmental advantages and promotes sustainability.

Social implications

The key perspectives about the applications of novel materials in the field of medicine are proposed.

Originality/value

The investigations about SLM contain an increasing amount of knowledge, motivated by the growing interest of the scientific community in this relatively young manufacturing process. This study can be seen as a compilation of relevant researches and findings in the field of the metal printing process.

Details

Rapid Prototyping Journal, vol. 27 no. 10
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 25 June 2020

Onur Ertuğrul, Zafer Çağatay Öter, Mustafa Safa Yılmaz, Ezgi Şahin, Mert Coşkun, Gürkan Tarakçı and Ebubekir Koç

The purpose of this paper is to evaluate the effect of post process combinations, e.g. hot isostatic pressing (HIP) only, HIP + T6 heat treatments, and T6 only, with different…

Abstract

Purpose

The purpose of this paper is to evaluate the effect of post process combinations, e.g. hot isostatic pressing (HIP) only, HIP + T6 heat treatments, and T6 only, with different aging time, on surface properties, microstructure and mechanical properties of stress-relieved AlSi10Mg parts produced by direct laser metal sintering.

Design/methodology/approach

HIP process and HIP + T6 heat treatments were applied to as stress-relieved direct laser metal sintered (DMLS) AlSi10Mg parts. Aging times of 4 and 12 h are selected to examine the optimum duration. To analyze the advantages of HIP process, a T6 heat treatment with 4 h of aging was also applied. Densities, open porosities and roughness values of as stress-relieved, HIPed, HIP + T6, and T6-only samples were measured. The samples were characterized by OM and SEM together with EDX analysis. An image analysis study was made to evaluate the inner pore structure, thereby to understand the mechanical behavior.

Findings

HIP process does not cause a significant change in surface porosity; yet it has a positive influence on inner porosity. HIP process results in a microstructure of the aluminum matrix surrounded by a network of micron and nano size Si particles. Additional heat treatment results in larger particles and precipitation. After HIPing, ductility increases but strength decreases. Samples aged 4 h present improved yield and tensile strength but decreased elongation, yet samples aged for 12 h reach a combination of optimum strength and ductility. The lower level of tensile strength and ductility in T6-only condition indicates that HIP process plays a crucial role in elimination of the porosity thus improves the effectiveness of subsequent heat treatment.

Originality/value

The study investigates the effect of post-process conditions and optimizes the aging time of the T6 heat treatment after HIP process in order to obtain improved mechanical properties. The stress-relieved state was chosen as the reference to prevent distortion during HIPing or heat treatment.

Details

Rapid Prototyping Journal, vol. 26 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

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