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Article
Publication date: 1 May 2002

O. Dufaud and S. Corbel

The characteristics of PZT suspensions have been studied and fit to stereolithography restraints. On one hand, researches concern the influence of fillers contents, dispersant…

1853

Abstract

The characteristics of PZT suspensions have been studied and fit to stereolithography restraints. On one hand, researches concern the influence of fillers contents, dispersant concentration, temperature and resins nature and amount on suspensions rheological behaviour. On the other hand, the influence of photoinitiator and PZT concentrations, density of energy and nature of the resin on suspension reactivity was investigated. These experiments have led to the choice of two photosensitive suspensions suitable for stereolithography purpose; which use depend on the fillers content. Furthermore, the stereolithography process has been modified owing to the balance between suspensions rheological and photochemical properties in order to shape piezoelectric ceramics. Thanks to these improvements, PZT ceramics/polymer composites dedicated to transducers and medical imaging applications have been fabricated.

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Rapid Prototyping Journal, vol. 8 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 September 1998

C. Hinczewski, S. Corbel and T. Chartier

Ceramic three‐dimensional parts can be produced by a stereolithography (SL) process using a ceramic suspension containing alumina powder, UV curable monomer, diluent…

2223

Abstract

Ceramic three‐dimensional parts can be produced by a stereolithography (SL) process using a ceramic suspension containing alumina powder, UV curable monomer, diluent, photoinitiator and dispersant. The monomer reacts to UV radiation (argon ionized laser) and is transformed into a solid polymer which is then removed by thermal treatment (debinding). Subsequent sintering of green parts leads to dense ceramic parts. The effect of each component on the rheology of the alumina suspensions has been studied first. Both the addition of dispersant and diluent and the increase in temperature allow a significant decrease of the viscosity of the suspensions. The highly loaded (more than 55 vol. per cent), homogeneous and stable suspensions have a shear thinning behaviour which is favourable for casting the layers. Adequate cured depth (above 200μm) and satisfactory transversal resolution have been obtained and these allow the production of ceramic parts, which demonstrates the feasibility of the process. Sintering at 1,580°C leads to dense ceramic parts with homogeneous microstructure. The process still needs to be optimized to improve even more the mechanical properties.

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Rapid Prototyping Journal, vol. 4 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 January 2008

A. Touati, S. Corbel and J.P. Corriou

Photolithography allows the fabrication of a solid polymer object through polymerization of a monomer resin by means of a laser source guided according to the data of computer…

67

Abstract

Photolithography allows the fabrication of a solid polymer object through polymerization of a monomer resin by means of a laser source guided according to the data of computer aided design. However, one drawback of this method is the inaccuracy of the dimensions of the objects related to the shrinkage phenomenon which depends on the polymerization, on the laser flux and on the used sweeping procedure. In this paper, the deformation of an isolated voxel (elementary volume) or a voxel interacting with its neighbor is described. This simulation is based on a kinetic model that takes into account the gel effect and a model of volumetric variation due to the difference of the length of the bonds between the monomer and polymer molecules.

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Multidiscipline Modeling in Materials and Structures, vol. 4 no. 1
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 3 April 2007

A.S. Limaye and D.W. Rosen

Mask projection micro‐stereolithography (MPμSLA) is an additive manufacturing process capable for fabricating true three‐dimensional microparts and hence, holds promise as a…

1804

Abstract

Purpose

Mask projection micro‐stereolithography (MPμSLA) is an additive manufacturing process capable for fabricating true three‐dimensional microparts and hence, holds promise as a potential 3D MEMS fabrication process. With only a few MPμSLA systems developed and studied so far, the research in this field is inchoate and experimental in nature. In order to employ the MPμSLA technology for microfabrication, it is necessary to model its part building process and formulate a process planning method to cure dimensionally accurate microparts. The purpose of this paper is to formulate a process planning method for curing dimensionally accurate layers.

Design/methodology/approach

A MPμSLA system is designed and assembled. The process of curing a single layer in resin using this system is modeled as the layer cure model. The layer cure model is validated by curing test layers. This model is used to formulate a process planning method to cure dimensionally accurate layers. The process planning method is tested by conducting a case study.

Findings

The layer cure model is found to be valid within 3 percent for most of the features and within 10 percent for very small features (<250μm). The paper shows that ray tracing can be effectively used to model the process of irradiation of the resin surface in a MPμSLA system.

Research limitations/implications

The process planning method is applicable only to those imaging systems, which are aberration limited as opposed to diffraction limited. The dimensional errors in the lateral dimensions of single layers cured by MPμSLA have been modeled, but not the vertical errors in 3D parts.

Originality/value

In this paper, a process planning method for MPμSLA has been presented for the first time.

Details

Rapid Prototyping Journal, vol. 13 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 October 2006

Ameya Shankar Limaye and David W. Rosen

Print‐through results in unwanted polymerization occurring beneath a part cured using Mask Projection Stereolithography (MPSLA) and thus creates errors in its vertical dimension…

938

Abstract

Purpose

Print‐through results in unwanted polymerization occurring beneath a part cured using Mask Projection Stereolithography (MPSLA) and thus creates errors in its vertical dimension. In this paper, the “Compensation Zone approach” is presented to avoid this error.

Design/methodology/approach

Compensation zone approach entails modifying the geometry of the part to be cured. A volume (compensation zone) is subtracted from underneath the CAD model in order to compensate for the increase in the Z dimension that would occur due to print‐through. Three process variables have been identified: thickness of compensation zone, thickness of every layer and exposure distribution across every image used to cure a layer. Analytical relations have been formulated between these process variables in order to obtain dimensionally accurate parts. The compensation zone approach is simulated on a test part with a slanted down‐facing surface.

Findings

The simulation results show that the compensation zone approach can reduce print‐ through errors significantly. In addition, it has been demonstrated numerically that the approach can also alleviate the problem of stair stepping.

Research limitations/implications

The derivations in the compensation zone approach are made with the following simplifying assumptions: exposure is additive; threshold model of resin cure is valid; the resin molecules underneath the part being cured are stationary; and the cleaning process can completely clean the part off the surrounding resin, due to these assumptions, the compensation zone model might require some calibration.

Originality/value

The errors in the vertical direction of a MPSLA build have been modeled for the first time. Compensation zone approach is a new concept.

Details

Rapid Prototyping Journal, vol. 12 no. 5
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 28 October 2024

Siavash Moayedi, Jamal Zamani and Mohammad Salehi

This paper aims to provide a full introduction, new classification, comparison and investigation of the challenges as well as applications of layerless 3D printing, which is one…

83

Abstract

Purpose

This paper aims to provide a full introduction, new classification, comparison and investigation of the challenges as well as applications of layerless 3D printing, which is one of the industry 4.0 pioneers.

Design/methodology/approach

Given the significance and novelty of uniform 3D printing, more than 250 publications were collected and reviewed in an unbiased and clear manner.

Findings

As a result, the majority of uniform parts printed in polymer form are known up to this point. In a novel division for better researchers’ comprehension, uniform printing systems were classified into three categories: oxygen inhibition (OI), liquid lubrication (LL) and photon penetration (PP), and each was thoroughly investigated. Furthermore, these three approaches were evaluated in terms of printing speed, precision and accuracy, manufacturing scale and cost.

Originality/value

The parameters of each approach were compared independently, and then a practical comparison was conducted among these three approaches. Finally, a variety of technologies, opportunities, challenges and advantages of each significant method, as well as a future outlook for layerless rapid prototyping, are presented.

Details

Rapid Prototyping Journal, vol. 31 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 16 January 2017

Xuan Song, Zeyu Chen, Liwen Lei, Kirk Shung, Qifa Zhou and Yong Chen

Conventional machining methods for fabricating piezoelectric components such as ultrasound transducer arrays are time-consuming and limited to relatively simple geometries. The…

1169

Abstract

Purpose

Conventional machining methods for fabricating piezoelectric components such as ultrasound transducer arrays are time-consuming and limited to relatively simple geometries. The purpose of this paper is to develop an additive manufacturing process based on the projection-based stereolithography process for the fabrication of functional piezoelectric devices including ultrasound transducers.

Design/methodology/approach

To overcome the challenges in fabricating viscous and low-photosensitive piezocomposite slurry, the authors developed a projection-based stereolithography process by integrating slurry tape-casting and a sliding motion design. Both green-part fabrication and post-processing processes were studied. A prototype system based on the new manufacturing process was developed for the fabrication of green-parts with complex shapes and small features. The challenges in the sintering process to achieve desired functionality were also discussed.

Findings

The presented additive manufacturing process can achieve relatively dense piezoelectric components (approximately 95 per cent). The related property testing results, including X-ray diffraction, scanning electron microscope, dielectric and ferroelectric properties as well as pulse-echo testing, show that the fabricated piezo-components have good potentials to be used in ultrasound transducers and other sensors/actuators.

Originality/value

A novel bottom-up projection system integrated with tape casting is presented to address the challenges in the piezo-composite fabrication, including small curing depth and viscous ceramic slurry recoating. Compared with other additive manufacturing processes, this method can achieve a thin recoating layer (as small as 10 μm) of piezo-composite slurry and can fabricate green parts using slurries with significantly higher solid loadings. After post processing, the fabricated piezoelectric components become dense and functional.

Details

Rapid Prototyping Journal, vol. 23 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 12 March 2020

Shekhar Srivastava, Rajiv Kumar Garg, Vishal S. Sharma, Noe Gaudencio Alba-Baena, Anish Sachdeva, Ramesh Chand and Sehijpal Singh

This paper aims to present a systematic approach in the literature survey related to metal additive manufacturing (AM) processes and its multi-physics continuum modelling approach…

916

Abstract

Purpose

This paper aims to present a systematic approach in the literature survey related to metal additive manufacturing (AM) processes and its multi-physics continuum modelling approach for its better understanding.

Design/methodology/approach

A systematic review of the literature available in the area of continuum modelling practices adopted for the powder bed fusion (PBF) AM processes for the deposition of powder layer over the substrate along with quantification of residual stress and distortion. Discrete element method (DEM) and finite element method (FEM) approaches have been reviewed for the deposition of powder layer and thermo-mechanical modelling, respectively. Further, thermo-mechanical modelling adopted for the PBF AM process have been discussed in detail with its constituents. Finally, on the basis of prediction through thermo-mechanical models and experimental validation, distortion mitigation/minimisation techniques applied in PBF AM processes have been reviewed to provide a future direction in the field.

Findings

The findings of this paper are the future directions for the implementation and modification of the continuum modelling approaches applied to PBF AM processes. On the basis of the extensive review in the domain, gaps are recommended for future work for the betterment of modelling approach.

Research limitations/implications

This paper is limited to review only the modelling approach adopted by the PBF AM processes, i.e. modelling techniques (DEM approach) used for the deposition of powder layer and macro-models at process scale for the prediction of residual stress and distortion in the component. Modelling of microstructure and grain growth has not been included in this paper.

Originality/value

This paper presents an extensive review of the FEM approach adopted for the prediction of residual stress and distortion in the PBF AM processes which sets the platform for the development of distortion mitigation techniques. An extensive review of distortion mitigation techniques has been presented in the last section of the paper, which has not been reviewed yet.

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Article
Publication date: 19 January 2010

Weizhao Zhou, Dichen Li and Hui Wang

The purpose of this paper is to present a new ceramic suspension to fabricate complex ceramic parts by stereolithography (SL).

2216

Abstract

Purpose

The purpose of this paper is to present a new ceramic suspension to fabricate complex ceramic parts by stereolithography (SL).

Design/methodology/approach

The process consists of preparation of aqueous ceramic suspensions, building ceramic parts, drying, subsequent binder removal, and sintering. Highly concentrated aqueous ceramic suspensions with a suitable viscosity are prepared, then a wet green ceramic part fabricated in a SL machine according to a 3D model is dried in polyethylene glycol. After binder removal sintering in a high temperature‐sintering furnace, a complex ceramic part is obtained.

Findings

The dispersant, volume fraction of ceramic powder and powder diameter could influence the viscosity of suspension. The cured depth is inversely proportional to the scanning speed of laser spot when the laser power keeps a constant and proportional to the concentration of monomer. The penetration depth and critical exposure are 0.27 mm and 231.2 mJ/cm2 from the experimental result of the windowpanes method. A new support structure could prevent the deformation of ceramic part from the suspension and improve the quality of ceramic parts. A complex impeller is fabricated at last.

Research limitations/implications

The dimensional and surface accuracy of ceramic SL should be further investigated.

Originality/value

This paper describes a new aqueous ceramic suspension to produce complex‐shaped ceramic parts by SL.

Details

Rapid Prototyping Journal, vol. 16 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 30 September 2021

Erfan Zamani and Theodoros Dounas

This study proposes a DfMA (Design for Manufacture and Assembly) based on unmanned aerial vehicle (UAV) and uses Iranian-Islamic Muqarnas as the main case study due to their…

274

Abstract

Purpose

This study proposes a DfMA (Design for Manufacture and Assembly) based on unmanned aerial vehicle (UAV) and uses Iranian-Islamic Muqarnas as the main case study due to their geometric modularity. In Islamic architecture, different geographic regions are known to have used various design and construction methods of “Muqarnas”, a type of decorated dome.

Design/methodology/approach

The paper presents a study on parametric analysis of the Iranian-Islamic Muqarnas and analyses its components, geometric relations and construction methods that should be considered when constructing one. This study aims to use the Muqarnas analysis as a driver to generate a DfMA basis on the UAVs and parametric fabrication. In Islamic architecture, different geographic regions use various design and construction methods of Muqarnas. There are four main parameters of the Muqarnas that define their classification; first, their three-dimensional shape, that provides volume. Second, the size of their modules is variable. Third, their own specific generative process-algorithm, and finally, the two-dimensional pattern plan that is used as a basis in the design. Thus, the authors present a global analytical study that drives a generative system to construct Muqarnas, through a careful balance of the four parameters.

Findings

This study thus presents a global analytical study that drives a generative system to construct Muqarnas, through a careful balance of four specifications. The paper reports the result of using a parametric tool, Grasshopper and parametric plugins, for creating a generative system of several types of Muqarnas. This synthetic translation aims at expanding our understanding of parametric analysis and synthesis of traditional architecture, advancing our understanding towards using parametric synthesis, with the scope to fabricate and assemble modules towards UAV-based fabrication of Muqarnas. To do so, the authors are taking advantage of their inherent repetition and recursion.

Originality/value

In the first step, this paper reviews studies on traditional Muqarnas (both Iranian and non-Iranian) and relevant parametric approaches. In the second step, the study aims to create a general generative system for Muqarnas. The creation of a generative system for Muqarnas is driven towards the creation of three-dimensional fabrication of their components so that these are assembled automatically using a swarm of UAVs. This particular drive imposes specific constraints in the parametric system, as the assembly of the final components, the authors posit, can only take place in a pick and place fashion.

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