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Article
Publication date: 11 February 2020

Zhenglin Du, Hui-Chi Chen, Ming Jen Tan, Guijun Bi and Chee Kai Chua

In recent years, additive manufacturing techniques have attracted much research attention because of their ability to fabricate customised parts with complex geometry. The…

Abstract

Purpose

In recent years, additive manufacturing techniques have attracted much research attention because of their ability to fabricate customised parts with complex geometry. The range of composites suitable for laser-based powder bed fusion technique is limited, and has not been investigated yet. This paper aims to study the fabrication of AlSi10Mg reinforced with nAl2O3 using the laser-based powder bed fusion technique.

Design/methodology/approach

An experimental approach was used to investigate the densification of AlSi10Mg–nAl2O3 composites using laser-based powder bed fusion technique. Optimisation of the porosity was performed, and microstructure evolution was evaluated.

Findings

In this study, laser volumetric energy density (approximately 109 J/mm3) was found to be required for the fabrication of AlSi10Mg–nAl2O3 composites with a relative volumetric density approximating 99%. The use of laser volumetric energy density resulted in larger grains. Columnar grain structure was observed via the use of electron backscatter diffraction mapping.

Originality/value

This paper examines the processing of new aluminium composite material suitable for the fabrication via the laser-based powder bed fusion technique.

Details

Rapid Prototyping Journal, vol. 26 no. 4
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 20 June 2017

Chor Yen Yap, Hongyi Kenneth Tan, Zhenglin Du, Chee Kai Chua and Zhili Dong

Selective laser melting (SLM) is an additive manufacturing technology that is gaining industrial and research interest as it can directly fabricate near full density…

Abstract

Purpose

Selective laser melting (SLM) is an additive manufacturing technology that is gaining industrial and research interest as it can directly fabricate near full density metallic components. The paper aims to identify suitable process parameters for SLM of processing of pure nickel powder and to study the microstructure of such products. The study also aims to characterize the microhardness and tensile properties of pure nickel produced by SLM.

Design/methodology/approach

A 24 factorial design experiment was carried out to identify the most significant factors on the resultant porosity of nickel parts. A subsequent experiment was carried out with a laser power of 350 W. The scanning speeds and hatch spacings were varied.

Findings

Scanning speed and hatch spacing have significant effects on the porosity of SLM components. A high relative density of 98.9 per cent was achieved, and microhardness of 140 to 160 Hv was obtained from these samples. A tensile strength 452 MPa was obtained.

Research limitations/implications

As the energy input levels were made in steps of 20 J/mm3 for the optimization study, the true optimal combination of parameters may have been missed. Therefore, researchers are encouraged to test the parameters with smaller variations in energy levels.

Practical implications

The paper provides a set of optimized parameters for the SLM of pure nickel. This study enables the three-dimensional (3D) printing of objects with nickel, which has applications in chemical catalyses and in microelectromechanical systems with its magnetostrictive properties.

Originality value

This research is the first in direct processing of pure nickel using SLM, with the identification of suitable process parameters. The study also provides an understanding of the porosity, microhardness, strength and microstructure of SLM produced nickel parts. This work paves the way for standardization of 3D printed nickel components and enables the applications of pure nickel via SLM.

Details

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

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Article
Publication date: 9 March 2010

Chee Kai Chua, Kah Fai Leong, Chu Sing Lim and Trong Thien Vu

The purpose of this paper is to detail the development of a multimedia courseware that enhances the learning of rapid prototyping (RP) among professionals, senior year and…

Abstract

Purpose

The purpose of this paper is to detail the development of a multimedia courseware that enhances the learning of rapid prototyping (RP) among professionals, senior year and graduate students.

Design/methodology/approach

The design and development of the multimedia courseware is based on a “visit a science museum” concept where each topic can be accessed depending on the interests or the needs of users. Factors that influence learning curve such as structure of information, application of visual and auditory components and human‐computer interface are addressed and discussed.

Findings

Instructions using multimedia significantly enhances the education process of RP technology. Methods to produce a good multimedia courseware have been introduced.

Originality/value

This paper describes the latest version of the multimedia courseware which is an accompaniment to the third edition of the book entitled Rapid Prototyping: Principles & Applications published in 2009.

Details

Rapid Prototyping Journal, vol. 16 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 February 2000

Chua Chee Kai, Chou Siaw Meng, Lin Sin Ching, Lee Seng Teik and Saw Chit Aung

While computerized tomography (CT) and magnetic resonance imaging (MRI) technologies are highly commendable for their applications and usage, sometimes cases involving…

Abstract

While computerized tomography (CT) and magnetic resonance imaging (MRI) technologies are highly commendable for their applications and usage, sometimes cases involving facial anatomy restoration may not necessarily require these highly sophisticated technologies. A suitable replacement that is also non‐contact and allows fast image capture is the laser digitizer surface scanner. This scanner takes only seconds to capture an image of the patient’s sound or healthy facial anatomy. By using the captured image data, it is possible, with the help of a surface data modeller rapid prototyping (RP) machine and vacuum casting machine, to manufacture the prosthesis for implant. Presents a novel approach for facial prosthesis fabrication through a case study of a prosthetic ear model using an integrated manufacturing system comprising the laser surface digitizer, surface data modeller, rapid prototyping system and vacuum casting system.

Details

Integrated Manufacturing Systems, vol. 11 no. 1
Type: Research Article
ISSN: 0957-6061

Keywords

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Article
Publication date: 8 June 2012

Mohammad Vaezi, Chee Kai Chua and Siaw Meng Chou

Today, medical models can be made by the use of medical imaging systems through modern image processing methods and rapid prototyping (RP) technology. In ultrasound…

Abstract

Purpose

Today, medical models can be made by the use of medical imaging systems through modern image processing methods and rapid prototyping (RP) technology. In ultrasound imaging systems, as images are not layered and are of lower quality as compared to those of computerized tomography (CT) and magnetic resonance imaging (MRI), the process for making physical models requires a series of intermediate processes and it is a challenge to fabricate a model using ultrasound images due to the inherent limitations of the ultrasound imaging process. The purpose of this paper is to make high quality, physical models from medical ultrasound images by combining modern image processing methods and RP technology.

Design/methodology/approach

A novel and effective semi‐automatic method was developed to improve the quality of 2D image segmentation process. In this new method, a partial histogram of 2D images was used and ideal boundaries were obtained. A 3D model was achieved using the exact boundaries and then the 3D model was converted into the stereolithography (STL) format, suitable for RP fabrication. As a case study, the foetus was chosen for this application since ultrasonic imaging is commonly used for foetus imaging so as not to harm the baby. Finally, the 3D Printing (3DP) and PolyJet processes, two types of RP technique, were used to fabricate the 3D physical models.

Findings

The physical models made in this way proved to have sufficient quality and shortened the process time considerably.

Originality/value

It is still a challenge to fabricate an exact physical model using ultrasound images. Current commercial histogram‐based segmentation method is time‐consuming and results in a less than optimum 3D model quality. In this research work, a novel and effective semi‐automatic method was developed to select the threshold optimum value easily.

Details

Rapid Prototyping Journal, vol. 18 no. 4
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 September 1997

Chua Chee Kai and Leong Kah Fai

Rapid prototyping (RP) is fast becoming a “strategic” technology, one that cannot be simply overlooked. This is because the production of a physical prototype from the…

Abstract

Rapid prototyping (RP) is fast becoming a “strategic” technology, one that cannot be simply overlooked. This is because the production of a physical prototype from the computer model can be achieved in a very short turnaround time and without the fuss required by NC programming systems. In Singapore, like many countries around the world, there is great interest in this emerging technology. Discusses the evolution of the RP scene in Singapore from 1988 to 1997.

Details

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

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Article
Publication date: 1 March 2006

Ker Chin Ang, Kah Fai Leong, Chee Kai Chua and Margam Chandrasekaran

The purpose of this paper is to investigate the mechanical properties and porosity relationships in fused deposition modelling (FDM) fabricated porous structures.

Abstract

Purpose

The purpose of this paper is to investigate the mechanical properties and porosity relationships in fused deposition modelling (FDM) fabricated porous structures.

Design/methodology/approach

Porous structures of numerous build architectures aimed at tissue engineering (TE) application were fabricated using the FDM. The employment of FDM to fabricate these non‐random constructs offers many advantages over conventional scaffold fabrication techniques as patient specific scaffolds with well‐defined architectures and controllable pore sizes can be fabricated accurately and rapidly. There exist several FDM parameters that one needs to specify during the scaffold fabrication process. These parameters, which can be interdependent and exhibit varying effects on scaffold properties, were identified and examined using the design of experiment (DOE) approach. Essentially, the effects of five FDM process parameters, namely air gap, raster width, build orientation, build layer and build profile, on the porosity and mechanical properties of acrylonitrile‐butadienene‐styrene (ABS) scaffold structures with three‐dimensional interconnectivity were investigated in two designed experiments. Statistical analyses of the data were performed and the respective factors that have significant influence on the porosity and mechanical properties of the scaffolds were identified. The relationship between scaffold's mechanical properties and porosity was thereafter established empirically.

Findings

Models of TE scaffolds of numerous build architectures were successfully fabricated using different parameter settings on the FDM. The DOE approach determined air gap and raster width as the most significant parameters in affecting the porosity and mechanical properties of the ABS scaffold structures. The relationship between scaffolds' mechanical properties and porosity was determined to be logarithmic, with the best mechanical properties observed in scaffolds of low porosity.

Originality/value

The paper highlights how the application FDM to tissue scaffold application can overcome most of the limitations encountered in the conventional techniques.

Details

Rapid Prototyping Journal, vol. 12 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 9 March 2010

Florencia Edith Wiria, Novella Sudarmadji, Kah Fai Leong, Chee Kai Chua, E. Wei Chng and Chian Chai Chan

In recent years, selective laser sintering (SLS) has been used in the biomedical field, including building small‐scaled biomedical devices such as tissue engineering…

Abstract

Purpose

In recent years, selective laser sintering (SLS) has been used in the biomedical field, including building small‐scaled biomedical devices such as tissue engineering scaffolds and drug delivery devices. A compact adaptation system for the SLS is needed to obtain a more effective and efficient way of sintering small‐scale prototypes so as to reduce powder wastage. Limitations of available smaller‐scale adaptation devices include the need of additional electrical supplies for the device. The purpose of this paper is to report the development of such a system to be mounted at the SLS part bed without any additional energy supply.

Design/methodology/approach

The compact adaptation device works on the concept of transferring the motion of the SLS part bed onto the part bed of the compact adaptation device. The device is an integrated attachment that is fixed onto the building platform of the SLS. The gear system of the device lifts the powder supply bed at both sides of the device simultaneously when the part bed at the center of the device is lowered. To further increase powder saving, an improved powder delivery system named alternative supply mechanism (ASM) is mounted on top of the roller to be coupled together with the compact adaptation device.

Findings

Powder saving up to 6.5 times compared to using full build version of the Sinterstation 2500 has been achieved by using the compact adaptation device. Furthermore, powder wastage has been reduced by 84 percent when using the ASM compared to the compact adaptation device alone.

Originality/value

The paper demonstrates the development and viability of adaptation devices for SLS to significantly reduce powder consumption by using solely mechanical means to build small parts without using external power supply.

Details

Rapid Prototyping Journal, vol. 16 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 5 October 2010

Florencia Edith Wiria, Kah Fai Leong and Chee Kai Chua

Tissue engineering (TE) involves biological, medical and engineering expertise and a current engineering challenge is to provide good TE scaffolds. These highly porous 3D…

Abstract

Purpose

Tissue engineering (TE) involves biological, medical and engineering expertise and a current engineering challenge is to provide good TE scaffolds. These highly porous 3D scaffolds primarily serve as temporal holding devices for cells that facilitate structural and functional tissue unit formation of the newly transplanted cells. One method used successfully to produce scaffolds is that of rapid prototyping. Selective laser sintering (SLS) is one such versatile method that is able to process many types of polymeric materials and good stability of its products. The purpose of this paper is to present modeling of the heat transfer process, to understand the sintering phenomena that are experienced by powder particles in the SLS powder bed during the sintering process. With the understanding of sintering process obtained through the theoretical modeling, experimental process of biomaterials in SLS could be directed towards the appropriate sintering window, so as not to cause unintentional degradation to the biomaterials.

Design/methodology/approach

SLS uses a laser as a heat source to sinter parts. A theoretical study based on heat transfer phenomena during SLS process was carried out. The study identified the significant biomaterial and laser beam properties that were critical to the sintering result. The material properties were thermal conductivity, thermal diffusivity, surface reflectivity and absorption coefficient.

Findings

The influential laser beam properties were laser power and scan speed, which were machine parameters that can be controlled by users. The identification of the important parameters has ensured that favorable sintering conditions can be achieved.

Research limitations/implications

The selection of biopolymer influences the manner in which energy is absorbed by the powder bed during the SLS process. In this paper, the modeling and investigative work was validated by poly(vinyl alcohol) which is a biomaterial that has been used for many biomedical and pharmaceutical purposes.

Practical implications

The paper can be the foundation for extension to other types of biomaterials including biopolymers, bioceramics and biocomposites.

Originality/value

The formulation of the theory for heat transfer phenomena during the SLS process is of significant value to any studies in using SLS for biomedical applications.

Details

Rapid Prototyping Journal, vol. 16 no. 6
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 June 1997

Nan‐Shing Ong, CheeKai Chua and Eng‐Wah Lee

Presents the development of an AutoCAD development system (ADS) application program for the automatic analysis of parts in mechanical assembly. The primary goal is to…

Abstract

Presents the development of an AutoCAD development system (ADS) application program for the automatic analysis of parts in mechanical assembly. The primary goal is to provide design engineers with a tool for extracting the part’s characteristics from the 3‐D solid model AutoCAD database. With this information and other non‐geometric information, the time for assembling the part can be determined. Describes the algorithms used to evaluate the rotational symmetries from the solid model database. Twelve 3‐D solid models are designed to evaluate the program capabilities. The overall performance of the program is satisfactory in terms of speed. It also provides a low‐cost PC‐based, fully‐functional alternative to the more expensive workstation‐based analysis program.

Details

Integrated Manufacturing Systems, vol. 8 no. 3
Type: Research Article
ISSN: 0957-6061

Keywords

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