Characterization of an aluminum-filled polyamide powder for applications in selective laser sintering.pdf

Short communication Characterization of an aluminum-fi lled polyamide powder for applications in selective laser sintering Alida Mazzoli *, Giacomo Moriconi, Marco Giuseppe Pauri Department of Materials and Environment Engineering and Physics (FIMET), Faculty of Engineering, Technical University of Marche, Via Brecce Bianche, 60131 Ancona, Italy Received 31 May 2005; accepted 23 November 2005 Available online 18 January 2006 Abstract Solid free-form fabrication (SFF) techniques use layer-based manufacturing to create physical objects directly from computer-gener- ated models. Using an additive approach to manufacture shapes, SFF systems join liquid, powder or sheet materials. Selective laser sin- tering (SLS) is a SFF technique by which parts are built layer-by-layer off ering the key advantage of the direct manufacturing of functional parts. In SLS, a laser beam is traced over the surface of a tightly compacted powder made of thermoplastic material. In this paper is characterized a new aluminum-fi lled polyamide powder developed for applications in SLS. This material is promising for many applications that require a metallic look of the part, good fi nishing properties, high stiff ness and higher part quality. ? 2005 Elsevier Ltd. All rights reserved. 1. Introduction Solid free-form fabrication (SFF) refers to the physical modelling of a design using a special class of machine tech- nology. SFF systems quickly produce models and proto- typepartsfrom3-Dcomputer-aideddesign(CAD) models, 3-D digitizing systems acquired data, computer- ized tomography (CT) and magnetic resonance imaging (MRI) scan data. The physical object is manufactured layer-by-layer, transforming the three-dimensional prob- lem in a bidimensional one. SFF systems join liquid, pow- der or sheet materials to manufacture the physical object. Layer-by-layer, SFF machines fabricate plastic, wood, ceramic, metal and composite parts using thin, horizontal cross-sections of the computer-designed model. In contrast to traditional machining methods (i.e. com- puter numerically controlled machines CNC), the major- ity of SFF systems fabricate parts using an additive procedure,ratherthanmaterialremoval(subtractive approach). Therefore, this type of fabrication is uncon- strained by the limitations attributed to conventional machining approaches. In fact, there are no problems of tool clash and any geometrical shape can essentially be reproduced to a high degree of accuracy, in the order of the tenth or hundredth of millimetre, on the basis of the selected material 1,2. Most of the SFF techniques can pro- duce high quality three-dimensional parts, with varying degrees of complexity, size and shape by means of various photochemical, laser sintering, guided deposition, extrusion layering or sculpting processes. SFF parts were, fi rstly, used as visual aids, but with the development of new materials it is now possible to make, for example, investment casting patterns, casting cores and moulds, functional prototypes and mould inserts for injection. The selective laser sintering (SLS) process is one of the most eff ective and versatile SFF techniques available today 3. Developed by Carl Deckard for his master thesis at the University of Texas, SLS was patented in 1989. SLS is a technique by which objects are built layer-by-layer from CAD data fi les exported in the industry-standard exchange fi le format STL. Stereolithography format (STL) is a boundary representation that consists of a simple list of tri- angular facets 4. The basic material developed for SLS 0261-3069/$ - see front matter ? 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.matdes.2005.11.021 * Corresponding author. Tel.: +39 071 2204290; fax: +39 071 2204729. E-mail address: a.mazzoliunivpm.it (A. Mazzoli). Materials and Design 28 (2007) 9931000 Materials September 2003. p. 36370. Fig. 9. X-ray image: portion of cranial bone tissue (right) and AC sintered sample (left). Fig. 8. Compression, upper, and bending, lower, test of the sintered DF (black) and AC (grey) specimens. On the right the two samples, DF (a) and AC (b), before and after compression and bending. A. Mazzoli et al. / Materials and Design 28 (2007) 9931000999 2 Mazzoli A, Moriconi G, Germani M. Infl uence of diff erent manufac- turing techniques and materials on the accuracy of anatomical SFF models derived from CT data. In: Proceedings of the BIOMED-3 conference, Innsbruck; February 2005. p. 649. 3 Pham DT, Gault RS. A comparison of rapid prototyping technologies. Int J Mach Tools Manu 1998;38:125787. 4 Stereolithography interface specifi cation. Company Literature, 3D System Inc., 1988. 5 Kruth JP, Wang X, Laoui T, Froyen L. Lasers and materials for selective laser sintering. Assembly Autom 2003;23(4):35771. 6 DuraFormTMmaterialdatash