The ongoing trend of miniaturisation still requires innovative and reliable production methods, especially for true three-dimensional components. As one of the classical Solid Freeform Fabrication principles in the macro-scale world, stereolithography has successfully shown its suitability for producing micro- and meso-scale parts with highest geometrical complexity. ((Teaser Ende))

In recent years, Solid Freeform Fabrication (SFF) has proven to be a solid basis for the design, development and manufacturing of products and consumer goods from various industries (e.g. telecommunications, automotive industry, information technologies). Here, SFF can be used as a design tool during product development ("Rapid Prototyping"), or as a direct production method for complex shaped parts ("Rapid Manufacturing"). Mainly based on a layer-by-layer production method, parts are built in a stepwise fashion, using a virtually sliced 3-D CAD model, without tools or moulds, exemplary by selectively curing liquid resins, melting powders or cutting thin foils. All principles have in common "stacking" individually generated layers to form a three-dimensional model, mainly by using light sources or lasers during layer generation.

Apart from applications in the macro-sized world, innovative laser sources and handling concepts enable the use of SFF for micro- and meso-scale applications. Based on the classical concept, highly precise parts can be fabricated by curing a liquid polymer, technically known as stereolithography. From the bottom to the top, highly complex parts with internal geometries can be produced, which is not possible with any other production method (Figure 1). Innovative laser sources provide high quality beams that can be focused down close to the micron level, thus enabling the fabrication of ultra-fine features (< 10 µm). Compared to classical stereolithography, an increase of the process resolution up to factor 10 could be achieved. Besides demonstrator parts that effectively show the potential of the technology developed (Figure 2), components for micro-mechanical applications have already been realised (Figure 3).

The high quality of these parts in all directions has been proven by using a micro-computer tomography system. Spatial resolutions of approximately 10 µm have been successfully demonstrated, and thus high precision components for various applications in the mechanical or fluidic sector are conceivable.

The "Lasers in Manufacturing Conference' (LIM) by Wissenschaftliche Gesellschaft für Lasertechnik e. V. (WLT) will present Rapid-Manufacturing-Technologies and other laser-based processes at the World of Photonics Congress in Munich from 14 to 19 June 2008.
Figure 1: The stereolithography principle

Figure 2 (a)-(d): SEM image of a micro-chess figure fabricated with stereolithography (a), STL model (b), µCT scan of the fabricated part (c) and variance comparison (d). The turquoise and green areas indicate deviations of +/- 10 µm, respectively

Figure 3 (a), (b): SEM images of a micro-mechanical device (b), and a 3-D CAD model (a)


Kontakt:
Laser Zentrum Hannover e.V.,
Dipl.-Ing. André Neumeister,
Tel. +49 (0)511 2788 372,
E-mail: a.neumeister@lzh.de