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Article
Publication date: 1 March 1999

Gabriel Bugeda Miguel Cervera and Guillermo Lombera

A finite element model has been developed for the 3D simulation of the sintering of a single track during a selective laser sintering process (SLS). The model takes into account…

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Abstract

A finite element model has been developed for the 3D simulation of the sintering of a single track during a selective laser sintering process (SLS). The model takes into account both the thermal and the sintering phenomena involved in the process. Owing to the continuous movement of the laser beam the model takes also into account the transient nature of the problem. This is transformed into a pseudo‐static one through a transformation of the coordinates system of the equations. Nevertheless, this transformation introduces a convective term into the heat equations that produces instabilities in the solution. These instabilities have been solved by using a stream upwind Petrov Galerkin (SUPG) strategy together with a shock capturing scheme. Finally, a fixed point strategy is used for the solution of the analysis. The model has been tested through the solution of some examples.

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Rapid Prototyping Journal, vol. 5 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 June 1995

Gabriel Bugeda, Miguel Cervera, Guillermo Lombera and Eugenio Onate

Stereolithography (SLA) is one of the most important techniques used in rapid prototyping processes. It has a great industrial interest because it allows for dramatic time savings…

1208

Abstract

Stereolithography (SLA) is one of the most important techniques used in rapid prototyping processes. It has a great industrial interest because it allows for dramatic time savings with respect to traditional manufacturing processes. One of the main sources of error in the final dimensions of the prototype is the curl distortion effect owing to the shrinkage of the resin during the SLA process. Presents a study of the influence of different constructive and numerical parameters in the curl distortion, an analysis which was made using the computer code stereolithography analysis program, developed to model SLA processes using the finite element method. Also briefly presents this code.

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Rapid Prototyping Journal, vol. 1 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 January 2006

Ian Campbell

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Rapid Prototyping Journal, vol. 12 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 10 October 2018

Ali Khoshkhoo, Andres L. Carrano and David M. Blersch

The purpose of this paper is to elucidate the effect of part thickness and build orientation upon the type and magnitude of distortion in material jetting processes.

428

Abstract

Purpose

The purpose of this paper is to elucidate the effect of part thickness and build orientation upon the type and magnitude of distortion in material jetting processes.

Design/methodology/approach

Specimens with high (10:1) aspect ratio were printed in two orientations (XY and YX) and three thickness values (1, 3 and 6 mm) and scanned with a white-light profilometer to quantify distortion.

Findings

The results of this paper indicate that 1-mm thick specimens always distorted following a wavy edge type, while thicker specimens (3- and 6-mm) always distorted following a reverse coil set. The factor thickness, when measured with the indices height of the highest peak (H) and profile radius (R), was shown to be statistically significant, with 3-mm specimens experiencing distortions of 57 and 51 per cent, respectively, more severe than those in 6-mm specimens. The thickness effect is attributed to the percentage of build layers that receive maximum energy exposure (61-72 per cent in 1-mm, 87-91 per cent in 3-mm and 93-95 per cent in 6-mm specimens). With respect to the thinner 1-mm specimens, the factor orientation was found to be statistically significant with distortion 114 per cent less severe in the YX orientation when measured by the H index.

Originality/value

This paper provides the first known description of build orientation and part thickness effects on dimensional distortion as a pervasive consequence of the curing process in photopolymerization and explores one of the most common defects encountered in additive manufacturing. In addition to the characterization of the type and magnitude of distortion, the contributions of this paper also include establishing the foundation for design guidelines aiming at minimizing distortion in material jetting.

Details

Rapid Prototyping Journal, vol. 24 no. 9
Type: Research Article
ISSN: 1355-2546

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