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Article

Huang-Jan Hsu, Shyh-Yuan Lee, Cho-Pei Jiang and Richard Lin

This study aims to compare the marginal fit, flexural strength and hardness for a ceramic premolar that is constructed using dental computer aided machining (CAM) and…

Abstract

Purpose

This study aims to compare the marginal fit, flexural strength and hardness for a ceramic premolar that is constructed using dental computer aided machining (CAM) and three-dimensional slurry printing (3DSP).

Design/methodology/approach

Dental CAM and 3DSP are used to fabricate a premolar model. To reduce the fabrication time for 3DSP, a new composition of solvent-free slurry is proposed. Before it is fabricated, the dimensions of the green body for the premolar model are enlarged to account for the shrinkage ratio. A two-stage sintering process ensures accurate final dimensions for the premolar model. The surface morphology of the green body and the sintered premolars that are produced using the two methods is then determined using scanning electronic microscopy. The sintered premolars are seated on a stone model to determine the marginal gap using an optical microscope. The hardness and the flexural strength are also measured for the purpose of comparison.

Findings

The developed solvent-free slurry for 3DSP can be used to produce a premolar green body without micro-cracks or delamination. The maximal marginal gap for the sintered premolar parts that are constructed using the green bodies from dental CAM is 98.9 µm and that from 3DSP is 72 µm. Both methods produce a highly dense zirconia premolar using the same sintering conditions. The hardness value for the dental CAM group is 1238.8 HV, which is slightly higher than that for the 3DSP group (1189.4 HV) because there is a difference in the pre-processing of the initial ceramic materials. However, the flexural strength for 3DSP is 716.76 MPa, which is less than the requirement for clinical use.

Originality/value

This study verifies that 3DSP can be used to fabricate a zirconia dental restoration device that is as good as the one that is produced using the dental CAM system and which has a marginal gap that is smaller than the threshold value. The resulting premolar restoration devices that are produced by sintering the green bodies that are produced using 3DSP and dental CAM under the same conditions have a similar hardness value, which is four times greater than that of enamel. The flexural strength of 3DSP does not meet the requirement for clinical use.

Details

Rapid Prototyping Journal, vol. 25 no. 7
Type: Research Article
ISSN: 1355-2546

Keywords

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Article

Wei-Ting Chang, Huang-Jan Hsu, Cho-Pei Jiang, Shyh-Yuan Lee and Yuan-Min Lin

The aim of this paper is to examine the effects of light controlling system that combined high refractive particles (n-TiO2 [titanium dioxide – TiO2]) and tartrazine lake…

Abstract

Purpose

The aim of this paper is to examine the effects of light controlling system that combined high refractive particles (n-TiO2 [titanium dioxide – TiO2]) and tartrazine lake dye (TL dye) on thickness, flexural strength, flexural modulus and surface details of the 3D-printed resin.

Design/methodology/approach

Influences of different concentrations of n-TiO2 and TL dye in light-cured resin formulations for 3D printing (3DP) application were evaluated, including curing thickness, flexural strength and surface details under scanning electron microscopy.

Findings

The polymerization thickness of samples containing both n-TiO2 and TL dye was lower compared to samples with TL dye solely. Samples containing more n-TiO2 and more TL dye exhibited lower flexural strength and modulus. Ramp models showed that for samples containing 1 per cent TL dye, when their n-TiO2 content increased from 1 to 5 per cent, surface laminate structures became sharper. However, when the TL dye content doubled to 2 per cent, the surface laminate structures were indefinite compared to 1 per cent TL dye-containing counterparts.

Originality value

In visible-light 3DP, light controlling system in cooperate dye with high refractive particles provides better energy distribution and scattering control. High refractive particles, dyes and light exposure time had influenced the surface resolution and mechanical properties of the 3DP products.

Details

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

Keywords

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Article

Cho‐Pei Jiang, You‐Min Huang and Chun‐Ho Liu

This paper aims to introduce the principle of the mask exposure and scanning stereolithography (MESS) and to develop a simulation code to analyze the MESS process.

Abstract

Purpose

This paper aims to introduce the principle of the mask exposure and scanning stereolithography (MESS) and to develop a simulation code to analyze the MESS process.

Design/methodology/approach

Photopolymerization is a key reaction in stereolithography. It brings about molecular linkage and releases exothermic temperature. The shrinkage effect is the major cause of prototype deformation, and the shrinkage resulting from scanning and mask exposing is different. It is important to analyze the inaccuracy of each curing layer after the mask exposing in order to optimize the scanning parameters. A simulation code, based on dynamic finite element method, to analyze the shrinkage effect in accordance with scanning path and mask exposure pattern. A benchmark model has been proposed to validate the implementation of the developed code.

Findings

The simulation results show that the developed code can analyze the deformation in laser scanning, masking exposing and the MESS process. In benchmark model study, the sharp corner shrinks faster than rounded edge in mask pattern curing. Although the profile scanning can maintain the high accuracy in the MESS process, the residual stress is easily discovered inside of the sharp corner.

Originality/value

The developed simulation code can be applied for optimizing scan path and exposing time due to the analysis process in accordance with the drawing path and fabrication parameters.

Details

Rapid Prototyping Journal, vol. 12 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

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Article

Cho‐Pei Jiang, Jyun‐Ru Huang and Ming‐Fa Hsieh

Bone tissue engineering is an emerging field providing viable substitutes for bone regeneration. Poly(ε‐caprolactone) (PCL) is a good candidate for scaffold fabrication…

Abstract

Purpose

Bone tissue engineering is an emerging field providing viable substitutes for bone regeneration. Poly(ε‐caprolactone) (PCL) is a good candidate for scaffold fabrication due to its high mechanical strength and excellent resistance under moist conditions, but its hydrophobicity causes cell‐attached difficulties, thus limiting its clinical application. The paper aims to develop an air pressure‐aided deposition system for fabricating scaffolds made of synthesized PCL‐PEG‐PCL copolymers and to validate the biocompatibility and hydrophilicity improvement of fabricated scaffolds.

Design/methodology/approach

An air pressure‐aided deposition system that involves rapid prototyping technique has been developed to fabricate scaffolds for tissue engineering (TE) application. Poly(ethylene glycol) (PEG), a hydrophilic non‐ionic polymer, is adopted to reduce the hydrophobicity of PCL alone. The synthesis process of PCL‐PEG‐PCL copolymer is briefly introduced. Effect of viscosity in regard to scanning speed on the deposited strand is investigated. Scaffolds with different mean pore sizes are fabricated using the developed system. The fibroblast cells are seeded for culturing and biocompatibility of fabricated scaffolds are validated using methylthiazol tetrazolium assay.

Findings

The study finds that the air pressure‐aided deposition system is suitable for fabricating micro‐porous cellular scaffold, especially for thermal‐sensitive copolymers. In addition, the experimental results shows that at the molecular weight of 50,000, the molten form can be stably deposited through a heating nozzle at an air pressure of 0.3 MPa and no crack occurs after it solidifies. The scaffold with mean pore size of 339×396 μm is suitable for fibroblast binding and ingrowth. The synthesized copolymers are non‐toxic, biocompatible and can be used for biomedical application.

Research limitations/implications

This study shows that weight ratio of PEG, 0.1, enhances the hydrophilicity of copolymer. Improvement regarding the weight ratio of PEG is necessary. Important challenges for further research are to optimize the fabrication parameter and pore interconnection for eliminating pore size error and enhancing cells proliferation, respectively.

Originality/value

An air pressure‐aided deposition system is successfully proposed to construct 3D tissue scaffolds. In addition, synthesized PCL‐PEG‐PCL copolymers are verified for biocompatibility and successfully fabricated into tissue scaffold with different mean pore sizes.

Details

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

Keywords

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Article

Cho‐Pei Jiang

The purpose of this paper is to develop a novel two‐laser beam stereolithography system which has the advantages of low cost, fabrication time reduction and high accuracy.

Abstract

Purpose

The purpose of this paper is to develop a novel two‐laser beam stereolithography system which has the advantages of low cost, fabrication time reduction and high accuracy.

Design/methodology/approach

The wavelengths of the two semiconductor laser beams are determined to be 405 nm (blue light) and 532 nm (green light), respectively, according to the relative absorbance rate of the visible‐light curable resin (NAF202) used. The blue light laser is suitable for scanning the contour of objects because of its fast absorbance, thus giving a narrow cured depth. The green light laser is better suited to scanning the internal crosshatch to condense the fabrication time because of its deep penetration and its high power results in a wide cured width. A photoabsorber, carbon powder with an average diameter of 0.1 μm, is adopted to control the cured layer thickness. An adaptive crosshatch technique is introduced and applied to the fabrication process. Two benchmarks are proposed and fabricated using the developed system to evaluate the fabrication capability. Furthermore, a coordinate measuring machine is employed to evaluate the accuracy of the fabricated benchmark parts.

Findings

An optimal weight percentage of 1.5 is specified. The technique developed in this study is feasible for the fabrication of highly‐convoluted objects such as fan blades. The inclusion of the adaptive crosshatch technique in the developed system significantly reduces the fabrication time.

Originality/value

The results presented in this paper show that the developed system can fabricate objects quickly with high accuracy.

Details

Rapid Prototyping Journal, vol. 17 no. 2
Type: Research Article
ISSN: 1355-2546

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Article

Cho‐Pei Jiang

The purpose of this paper is to propose a method for fabricating tumor vessel phantom and then investigate the thermal dosage profile caused by high‐intensity‐focused…

Abstract

Purpose

The purpose of this paper is to propose a method for fabricating tumor vessel phantom and then investigate the thermal dosage profile caused by high‐intensity‐focused ultrasound (HIFU) surgery.

Design/methodology/approach

In this paper, a thermal sensitive powder has been added to silicon‐based gel as a vessel phantom raw material for displaying the thermal dosage profile caused by HIFU. A fused deposition modeling system was used for fabricating the shell casting mold and the vessel arbor mold. The arbor prototype, made of wax, was solidified in the cavity of vessel arbor mold. The vessel phantom object embedded with the arbor prototype was created in the shell mold casting process. The vessel phantom was obtained by immersing the vessel phantom object into hot water (65°C) for melting the vessel arbor prototype. A HIFU experiment has been conducted for verifying the feasibility of displaying the thermal dosage profile of the fabricated vessel phantom. The HIFU experimental parameters including the driving power of HIFU transducer, ultrasound exposure duration and volume flow rate were used for investigating the thermal dosage variation by the perfusion of vessel phantom.

Findings

The properties of fabricated mimicking phantom agree well with those of human tissue. The experimental results show that the proposed method can fabricate the Y‐type vessel phantom. The proposed method has been proved as a promising fabrication process in fabricating the vessel phantom and it displays the thermal dosage profile in HIFU experiment.

Originality/value

The proposed method and the developed experimental apparatus are helpful for pre‐clinical HIFU surgery.

Details

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

Keywords

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