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 A rapid prototyping technology that is said to be up to 50 times faster than layer-based methods is being developed by Direct Shaping Technologies GmbH of Germany. The process uses familiar thermoplastics such as polystyrene, polyethylene, polypropylene and other materials in essentially their intrinsic state. While there are geometric limitations, the technique is being aimed first at producing parts having shell-like geometries. Such items represent a substantial subset of all plastic parts. Direct Shaping is expected to be suitable for quickly producing low volumes of parts for medical, consumer and business applications without tooling.
The technique is similar to glass blowing: A pre-form, in this case a flat sheet of plastic, is heated by a CO2 laser imagewise in proportion to the amount of required deflection in the Z-direction of the sheet to form the final part. The quantity of heating generated by the laser is calculated from the CAD data that describes the part. Compressed air is then applied to the back of the sheet to force the softened plastic to deform upwards. The picture above and those below show several simple geometries formed in this way.
 In glass blowing, skill is required on the part of the artisan to get the correct result. The artist will re-heat the material and apply more air, or work the material by hand, many times until the proper effect is achieved. In contrast, Direct Shaping uses video cameras mounted above and to the side of the work to continuously measure the results and adjust the amount of heat applied by the laser and other parameters dynamically. Closing a loop around the process in this way effectively circumvents the numerous variables involved, according to the company's Carsten Duesterhoeft. Several cycles may be required to complete a part, but each can be fairly quick, on the order of a minute.
 
video cameras, etc., and a close-up of a part being formed. The minimum feature size and radius of curvature obtainable are similar in dimensions to the thickness of the original sheet, and such items as holes are formed by ancillary processes such as CNC or laser machining. In the long run, the company envisions incorporating secondary processes into the DS system itself. At present, the process is limited to producing walls at a maximum of 60 degrees from the plane of the sheet. However, according to Mr. Duesterhoeft it should be possible with development to produce both perpendicular walls and undercuts. The company is seeking strategic partners and additional venture financing.
For more info contact:
Direct-Shaping-Technologies GmbH
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