TIME COMPRESSION 73
for prototyping clear medical device housings and fluid flow analysis models due to its functional properties and high dimensional stability (Fig. 4). USP Class VI approval creates new opportunities for prototypes to be used in clinical trials.
Software developments
Of course, whatever material is selected for a stereolithography application, the way it is used can make a significant difference to the part’s performance and cost. And this is where software can have an impact. DSM Somos has developed a software application that enables lightweight prototypes to be created with enhanced structural integrity. Based on patented technology from the Milwaukee
School of Engineering (MSOE), Tetrashell hollow- build software uses MSOE’s Tetralattice technology to facilitate the manufacture of hollow stereolithography parts with variable skin thicknesses, supported by a Tetralattice support structure (Fig. 5). Potential application areas include investment casting patterns, reduced-density metal-clad composite structures, and lightweight large, thick-sectioned parts. DSM Somos believes that Tetrashell enables parts
to be built that would not have been cost-effective to create as solid parts – yet without compromising the parts’ structural integrity. Brian Bauman, a product development manager with DSM Somos, comments: “The Tetrashell software will allow stereolithography part builders to widely vary wall thickness, as well as to adjust support parameters – and consequently opens doors previously closed to stereolithography because of cost or weight considerations. Due to the overall reduction in mass, the Tetrashell hollow-build style will create material savings for customers with bulky parts, while at the same time increasing part accuracy.” While the developments from 3D Systems and DSM
Somos could be viewed as incremental innovations – albeit important ones – Huntsman Advanced Materials has unveiled its Araldite Digitalis rapid prototyping machine that uses an entirely new technology in conjunction with radiation-curing resins. Described as fundamentally different to other technologies, the Araldite Digitalis is neither based on lasers nor on light-reflecting MEMS (micro-electro mechanical system) as used in 3D printers. At the heart of the Araldite Digitalis is an MLS (MicroLightSwitch) exposure system that operates via a computer-controlled micro-mechanical shutter system that selectively exposes a larger surface area of resin in a single step. This type of exposure, in contrast to a laser that exposes one point at a time, is said to enable much faster and more accurate manufacturing of simple or complex parts. The Araldite Digitalis apparatus consists of three key
elements: the operating console, the vat enclosure with a recoater, and the exposure system. UV (ultraviolet) light from UV lamps is distributed through fibre optics onto the exposure bar where MLS units distribute UV light
Fig. 5. Tetrashell software facilitates the manufacture of hollow stereolithography parts with variable skin thicknesses, supported by a Tetralattice support structure.
www.engineerlive.com
Fig. 4. Watershed XC is used for prototyping clear medical device housings and fluid flow analysis models due to its functional properties and high dimensional stability.
pixels on to the resin surface. The computer-controlled shutter mechanisms steer the exposure of the UV light to avoid scattering, and micro lenses refocus the UV light after leaving the MLS. Importantly the illuminating angle is 90 degrees, which guarantees that uniformly high accuracy is always achieved. With its innovative technologies and potential to
reduce production times and costs, the Araldite Digitalis won the Euromold-Award 2008 Gold Prize in December 2008. The Euromold awards honour the three best products and services out of the broad spectrum of exhibits at Euromold. n
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