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1 – 10 of 182
Article
Publication date: 1 August 2006

Vijay Kumar Meena and Nagahanumaiah

The purpose of this paper is to optimise the electro‐discharge machining (EDM) parameters and investigate feasibility of using direct metal laser sintering (DMLS) parts as EDM…

1513

Abstract

Purpose

The purpose of this paper is to optimise the electro‐discharge machining (EDM) parameters and investigate feasibility of using direct metal laser sintering (DMLS) parts as EDM electrodes.

Design/methodology/approach

In this paper the effects of discharge current, pulse‐on‐time, flushing pressure are optimized for minimum tool wear rate (TWR), maximum metal removal rate (MRR) and minimum surface roughness (Ra). Taguchi‐based L9 orthogonal array has been used for performing experiments on EDM machining of EN 24 steel using DMLS electrodes. The grey relational analysis combined with ANOVA techniques have been employed to determine the optimal level as well as their significance.

Findings

Experimental results have shown that the performance characteristics of the EDM process (TWR, MRR and surface roughness) using DMLS electrode can be quantified and controlled effectively by grey relational approach presented in the study. Current is found to be the most affective parameter in EDM machining using DMLS electrode. Excessive DMLS tool (electrode) wear was also reported, which limits the use of DMLS tool for EDM machining and it has been found out that porosity (which was about 20 per cent) was one of the primary cause.

Research limitations/implications

This paper was focused on understanding the effects of important EDM parameters on three performance characteristics (TWR, MRR and surface roughness). While this study identifies that DMLS electrode wear rate is high and porosity could be one of the main cause, presently it does not cover the investigations on reducing the porosity level and its implications.

Practical implications

The DMLS material had shown huge potential to be used as EDM electrode. The current investigation established a structured experimental approach to understand the effects of EDM parameters on multi response characteristics. The results derived from this study helps to focus future research on two aspects including enriching the copper content and reducing the porosity level, thereby the benefits of lead time reduction in EDM electrode making could be realized.

Originality/value

The previous research attempts were not focussed on optimising the EDM machining process using rapid tooling electrodes. With the best of author's knowledge none of the researchers have reported these aspects especially for DMLS electrodes. Application of grey relational analysis for performance evaluation of rapid tooling‐based EDM electrodes (DMLS electrodes) appear to be completely new.

Details

Rapid Prototyping Journal, vol. 12 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 17 October 2017

Joshua Gale and Ajit Achuhan

Additive manufacturing (AM) processes involve a layer-by-layer sintering of metallic powders to produce fully functional three-dimensional parts. This layer-by-layer building…

Abstract

Purpose

Additive manufacturing (AM) processes involve a layer-by-layer sintering of metallic powders to produce fully functional three-dimensional parts. This layer-by-layer building process provides a unique opportunity to enhance mechanical properties by applying treatments that previously were possible only on the surface in traditional manufacturing techniques. The purpose of the study is to examine the effect of ultrasonic peening (UP) applied during a layer-by-layer direct metal laser sintering (DMLS) fabrication of 316L stainless steel on its mechanical properties and microstructure.

Design/methodology/approach

Uniaxial tensile tests were performed at 1.27 mm/s to determine the effect of UP treatment on the average global behavior of a 316L part, whereas hardness measurements using nanoindentation were performed to determine the modification of local mechanical properties. Compressive buckling tests at a loading rate of 3 mm/min were performed on sample coupons with a large aspect ratio to evaluate the effect of UP on any potential delamination of DMLS layers. Techniques such as optical and scanning electron microscopy (SEM) imaging were utilized to determine the effect of UP on the microstructure.

Findings

Overall, significant modification in mechanical properties such as hardness and yield strength, along with microstructure, was observed. Large increases in both the average global and local mechanical properties, as well as a disruption in the columnar grain microstructure, was observed in DMLS parts treated with UP treatment.

Originality/value

Results indicate an opportunity for UP to be used as an in-situ process during AM processes for dynamically altering the mechanical behavior, microstructure, and distortion due to residual stress formation, in a tunable fashion.

Details

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

Keywords

Open Access
Article
Publication date: 9 February 2024

Martin Novák, Berenika Hausnerova, Vladimir Pata and Daniel Sanetrnik

This study aims to enhance merging of additive manufacturing (AM) techniques with powder injection molding (PIM). In this way, the prototypes could be 3D-printed and mass…

Abstract

Purpose

This study aims to enhance merging of additive manufacturing (AM) techniques with powder injection molding (PIM). In this way, the prototypes could be 3D-printed and mass production implemented using PIM. Thus, the surface properties and mechanical performance of parts produced using powder/polymer binder feedstocks [material extrusion (MEX) and PIM] were investigated and compared with powder manufacturing based on direct metal laser sintering (DMLS).

Design/methodology/approach

PIM parts were manufactured from 17-4PH stainless steel PIM-quality powder and powder intended for powder bed fusion compounded with a recently developed environmentally benign binder. Rheological data obtained at the relevant temperatures were used to set up the process parameters of injection molding. The tensile and yield strengths as well as the strain at break were determined for PIM sintered parts and compared to those produced using MEX and DMLS. Surface properties were evaluated through a 3D scanner and analyzed with advanced statistical tools.

Findings

Advanced statistical analyses of the surface properties showed the proximity between the surfaces created via PIM and MEX. The tensile and yield strengths, as well as the strain at break, suggested that DMLS provides sintered samples with the highest strength and ductility; however, PIM parts made from environmentally benign feedstock may successfully compete with this manufacturing route.

Originality/value

This study addresses the issues connected to the merging of two environmentally efficient processing routes. The literature survey included has shown that there is so far no study comparing AM and PIM techniques systematically on the fixed part shape and dimensions using advanced statistical tools to derive the proximity of the investigated processing routes.

Article
Publication date: 18 January 2016

Ana R. Lapcevic, Danimir P Jevremovic, Tatjana M Puskar, Robert J. Williams and Dominic Eggbeer

The purpose of this paper is to analyse structure and measure hardness of Co-Cr dental alloy samples made with two different technologies, conventional casting method (CCM…

Abstract

Purpose

The purpose of this paper is to analyse structure and measure hardness of Co-Cr dental alloy samples made with two different technologies, conventional casting method (CCM samples) and additive direct metal laser sintering technology (DMLS samples), and to compare the results.

Design/methodology/approach

CCM samples were made in a conventional casting machine, using remanium 800+ Co-Cr dental alloy (Dentaurum, Ispringen, Germany). DMLS samples were fabricated out of EOS CC SP2 Co-Cr alloy (EOS, GmbH, Munich, Germany) using DMLS technology. Samples for structural analysis were plate-shaped (10 × 10 × 1.5 mm3) and for the hardness test were prismatic-shaped (55 × 10.2 × 11.2 mm3). Structure was analysed via an inverting microscope and colour metallography method.

Findings

CCM samples have a dense, irregular dendritic mesh, which is typical for the metallic phase of the Co-Cr dental alloy. DMLS alloy has a more homogenous and more compact structure, compared to CCM. Metals, the alloy basis consists of, form semilunar stratified layers, which are characteristic for the additive manufacturing (AM) technique. Hardness values of DMLS (mean value was 439.84 HV10) were found to be higher than those of CCM (mean value was 373.76 HV10).

Originality/value

There are several reports about possible use of AM technologies for manufacturing dental devices, and investigation of mechanical properties and biocompatibility behaviour of AM-produced dental alloys. Microstructure of Co-Cr alloy made with DMLS technology has been introduced for the first time in the present paper.

Details

Rapid Prototyping Journal, vol. 22 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 29 May 2009

Nagahanumaiah and B. Ravi

The purpose of this paper is to present the results of an investigation into the effect of injection molding process parameters on the performance of direct metal laser sintered …

2737

Abstract

Purpose

The purpose of this paper is to present the results of an investigation into the effect of injection molding process parameters on the performance of direct metal laser sintered (DMLS) mold in producing quality Zytel nylon 66 plastic parts with consistency in part shrinkage and shot/part weight.

Design/methodology/approach

The injection mold for an industrial component (hub gear) was fabricated in EOS M‐250 machine using bronze‐based material. The effect of four injection molding parameters (injection pressure, melt temperature, speed, and injection time) on part shrinkage and weight were studied experimentally using L9 orthogonal array. The weight of the part just after ejecting from the cavity, and the average shrinkage measured after cooling, were used in grey relational analysis technique to assess the effect of each molding parameter. Further, surface properties such as surface finish, wear, scratch and corrosion resistance tests were conducted on DMLS mold material samples, in order to evaluate its use in rapid manufacturing applications.

Findings

The study found that injection speed and melt temperature have significant influence on part weight and shrinkage. The optimized molding process variables were slightly more in the case of DMLS molds as compared with the parameters suggested in the plastic datasheet. Scanning electro microscope (SEM) analysis of the mold surface after producing 5,000 glass filled Nylon 66 (Zytel) moldings did not indicate any surface degradation, confirming the use of DMLS mold in rapid manufacturing of few thousands of moldings.

Research limitations/implications

The grey relational analysis does not compute the effect of any two or more variables together unlike ANNOVA. Second, this study alone is not enough to estimate life of DMLS mold, although 5,000 glass filled nylon 66 moldings are successfully produced without any damage on mold surface.

Practical implications

This investigation demonstrates a generic approach of using grey relational analysis to quantify the effect of different molding process variables on selected quality parameters. This method can be easily extended for new processes and materials. The preliminary tests on surface finish, scratch, wear and corrosion resistance performed on DMLS mold samples have highlighted the need for improving surface properties to enhance their life. The authors are currently working on hard coating of DMLS molds as one of the solutions.

Originality/value

Use of grey relational analysis is new to the problem of injection molding process optimization. Moreover, effect of injection molding parameters on part weight and shrinkage in DMLS mold has not been studied previously. This study helps while considering DMLS molds for manufacturing few thousands of parts.

Details

Rapid Prototyping Journal, vol. 15 no. 3
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…

2403

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: 23 January 2007

P. Mognol, M. Rivette, L. Jégou and T. Lesprier

To propose a method to manufacture a hybrid rapid tool (a multi component tool).

1350

Abstract

Purpose

To propose a method to manufacture a hybrid rapid tool (a multi component tool).

Design/methodology/approach

The part is decomposed into multi component prototype instead of a part made from a single piece. First, this method is based on a topological analysis of the tool. Features are regrouped starting from the numerical definition of the die. Second, the manufacturing possibilities of the high speed milling (HSM), direct metal laser sintering (DMLS) and electro discharge machining (EDM) process are analyzed. Finally this information is synthesized to obtain solutions. This method is validated by industrial example.

Findings

A method is proposed to choose the best manufacturing process in order to optimize the manufacture of a “hybrid rapid tooling” between three processes: HSM, DMLS and EDM. So, it is possible to obtain the different components of the hybrid rapid tooling according to the envisaged process.

Research limitations/implications

The final goal is to propose a software assistant used in association with CAD system during the design of hybrid rapid tooling. An important work concerning the features recognition must be implemented. The assembly of the different parts of the hybrid rapid tooling must be considered and optimized.

Practical implications

This method allows the selection of the best process among EDM, HSM and DMLS technologies form manufacturing tools.

Originality/value

The analysis of manufacturing hybrid rapid tooling has not been studied yet.

Details

Rapid Prototyping Journal, vol. 13 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 12 March 2018

Hamza Hassn Alsalla, Christopher Smith and Liang Hao

The purpose of this paper is to study new process parameters which were selected to achieve the full density of Ti-6Al-4V samples in different building orientations and…

Abstract

Purpose

The purpose of this paper is to study new process parameters which were selected to achieve the full density of Ti-6Al-4V samples in different building orientations and investigate fracture toughness property and its relation to the microstructure, an area which has not previously been reported in full detail and which may offer information to a designer. Direct metal laser sintering (DMLS) is an additive manufacturing technique that directly manufactures three-dimensional parts, layer-by-layer, to scan and melt metal powders for aerospace applications.

Design/methodology/approach

Hardness and tensile tests were carried out to evaluate the effect of consolidation on the mechanical performance of specimens made at three different building directions. Optical and electron microscopy were used to characterise the microstructure of the DMLS specimens and their effects on the fractures and mechanical properties.

Findings

It was found that the built samples have an excellent density at 4.5 g/cm, and the sample surfaces parallel to the building direction are rougher than the perpendicular surfaces. The fracture toughness result was higher than that of the cast material for the same alloy and higher than the Ti-6Al-4V parts fabricated by electron beam melting. This results in the superior mechanical properties of DMLS, while slightly lower in the zy direction owing to cracks, porosity and surface finish.

Research limitations/implications

The tensile strength was found to be higher than the wrought material, and the samples exhibited brittle fractures owing to the martensitic phase, which is caused by a high temperature gradient, and the mechanical properties change with the change in the microstructures at different building directions.

Originality/value

This paper contains original research.

Details

Rapid Prototyping Journal, vol. 24 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 20 March 2017

Gabriel Antonio Mendible, Jack A. Rulander and Stephen P. Johnston

This study aims to evaluate the performance of injection molding inserts produced via rapid and conventional manufacturing techniques considering the mechanical and thermal…

1502

Abstract

Purpose

This study aims to evaluate the performance of injection molding inserts produced via rapid and conventional manufacturing techniques considering the mechanical and thermal performance of the tools as well as the resulting molded part quality.

Design/methodology/approach

Three insert materials and manufacturing techniques were evaluated, jetted photopolymer (PolyJet) 3D printing using digital ABS, direct metal laser sintering (DMLS) using bronze and machining using stainless steel. Molding trials were performed, and the insert surface temperature, longevity and part properties were evaluated. Complementary information was acquired using computer simulation.

Findings

Similar behavior and part quality were observed in machined and DMLS inserts. The latter were used for 500 cycles without any signs of failure. PolyJet inserts had increased cycle time and slower rate of cooling which increased shrinkage and crystallinity in the molded parts. PolyJet inserts could be produced quickly at a lower cost than machined or DMLS inserts.

Research limitations/implications

Cooling within the insert was not studied; inserts were cooled indirectly by the mold plates behind them. Subsequent studies will incorporate cooling lines directly into the inserts.

Originality/value

Little research has been done to understand the thermal behavior of inserts manufactured via rapid tooling techniques. This study provides a direct comparison between rapid tooling techniques, which is supported by simulation results and analysis of the actual molding properties.

Details

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

Keywords

Article
Publication date: 3 May 2016

Pawel Rokicki, Bogdan Kozik, Grzegorz Budzik, Tomasz Dziubek, Jacek Bernaczek, Lukasz Przeszlowski, Olimpia Markowska, Bartlomiej Sobolewski and Arkadiusz Rzucidlo

The purpose of this paper is to present the methodology for manufacturing of aircraft transmission gears using incremental method of rapid prototyping (RP) – direct metal laser…

Abstract

Purpose

The purpose of this paper is to present the methodology for manufacturing of aircraft transmission gears using incremental method of rapid prototyping (RP) – direct metal laser sintering (DMLS). The production of prototypes from metallic powders using described system allows the execution of final elements of complex structures with additional economic impacts.

Design/methodology/approach

The paper describes the use of selective laser sintering method (DMLS) by EOS Company. Whole chain of production of prototype is presented with the addition of geometric accuracy measurements by blue light laser device.

Findings

Presented in the research analysis of SLS/SLM technologies as rapid manufacturing systems shows that they can be applied in the production of prototypes used in the manufacturing process of gears for propulsion systems in aviation industry. Also, very important is the geometrical accuracy of gear prototypes produced by incremental methods. It determines subsequent treatment steps for aircraft propulsion system gears.

Practical Implications

The use of RP techniques as an alternative for conventionally used manufacturing method has mainly an economic impact related to the cost of time-consuming process and amount of defected elements appearing in serial production.

Originality/value

This paper presents possibility to use RP – DMLS system – for propulsion elements of aircraft structure. This research is original because of the complex description of the whole chain of manufacturing process. Additionally, geometrical accuracy measurement methodology by blue light presented with the RP method of manufacturing gives the research a unique characteristic.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 88 no. 3
Type: Research Article
ISSN: 1748-8842

Keywords

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