Rapid prototyping techniques gain ground in volume production

Citation

(2004), "Rapid prototyping techniques gain ground in volume production", Assembly Automation, Vol. 24 No. 1. https://doi.org/10.1108/aa.2004.03324aab.001

Rapid prototyping techniques gain ground in volume production

Rapid prototyping techniques gain ground in volume production

Keywords: Rapid prototyping, Lasers, Sintering

At a recent international user meeting held at the Munich headquarters of a leading laser sintering machine manufacturer, EOS, participants from 18 countries were presented with the latest developments in e-Manufacturing. This is a word coined by the German company to describe the rapid manufacture not only of prototypes, but also increasingly of tooling or the finished product itself in small-to-medium size batches directly from a CAD file or other electronic data. The technology covers three broad areas – plastic, metal and sand.

In addition to presentations by the company on its latest products, powders and techniques, a number of case studies were cited by customers, as described later.

The Swiss company, Phonak, uses an EOS laser sintering system for the series production of plastic shells for its digital hearing aids, saving time and money while at the same time improving the product. Laser sintered in the ear hearing devices have an optimum fit and grip, according to Phonak's Dr Hans Hessel, despite the difficulty of manufacturing a customised hearing aid due to the complicated anatomy of the human ear.

Hettich Centrifuges from Tuttlingen, Germany has adopted EOS technology for volume production of its new centrifuges. By laser sintering directly in plastic without the need for tooling, Hettich is able to fabricate a highly complicated centrifuge while reducing the number of components which later have to be assembled. Not only is the manufacture of the new centrifuges faster and cheaper, but the products also have improved functionality.

Design company Freedom of Creation, Amsterdam, uses EOS laser sintering for fabricating designer products of all kinds, from fabrics to jewellery and lamps. Treviso Tecnologia, Italy, described how its CE marked, laser sintered sunglasses, which are finished fully automatically, are being marketed as a limited-edition product (Plate 1).

Plate 1 These limited-edition sunglasses were manufactured by Treviso Tecnologia, Italy, using an EOS laser sintering machine and fine polyamide powder

Latest trends in the manufacture of tooling directly from laser sintered metal (DirectTool) were described. Rapid tooling, i.e. manufacturing moulds in a short lead time for producing products such as a small number of injection moulded or die-cast parts, is becoming faster. A good example is the so-called “minute mould” concept developed by the Finnish company, Rapid Product Innovations, in which a small series of injection moulded parts was produced from 2D drawings within just 15h.

DirectTool is being used increasingly for series production of tooling, according to Peter Decloedt of QuickTools, Belgium, who described a range of examples where even challenging projects have been successfully performed quickly and cost-effectively. For example, tooling production and the manufacture of 20,000 covers in polybutylene terephthalate (PBT) +30GF (30 per cent glass fibre) was achieved in just 2 weeks using laser sintered inserts.

These trends are supported by the increasing use of novel tooling concepts, i.e. those which optimise the characteristics and benefits of laser sintering rather than sticking to traditional methods. For instance, various EOS metal powder sintering machine customers are using “frameless tooling” where no bolster is needed. Dr Dirk Hennigs of Fraunhofer Institute for Manufacturing and Advanced Materials (IFAM) presented ongoing research to develop efficient ways of building large and complex tools by assembling them in segments.

At this year's GIFA 2003 foundry fair in Düsseldorf, EOS presented e-Manufacturing for the first time directly to the casting industry together with three sub-exhibitors, which staged practical demonstrations for producing cast parts “live” by laser sintering. The design flexibility of DirectCast technology was presented for the manufacture of complex sand cores and moulds for prototypes, one-off parts and spare parts as well as small series runs offering high accuracy, detail resolution and surface quality.

As a result of an EU-sponsored project directed mainly by the Fraunhofer Institute of Production Technology in Aachen, EOS showed for the first time at GIFA parts which had been laser sintered directly in zirconia silicate. This is a ceramic material which is normally used for casting aluminium alloys or low-alloy steels. The project illustrated the technical feasibility of the technology and enabled applications, requirements and specifications to be evaluated. The possibility of manufacturing ceramic cores and shells for investment casting directly by laser sintering met with considerable interest and committed EOS to further investigation.

For further information, contact: Stuart Jackson, Regional Manager, UK and Eire, EOS Electro Optical Systems Ltd, The Innovation Centre, Warwick Technology Park, Gallows Hill, Warwick, CV34 6UW. Tel: 01926 623107; Fax: 01926 623108; E-mail: stuart.jackson@eos.info.; Web site: www.eos.info