Originally Published MPMN March 2006

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Laser Sintering Benefits Design and Manufacture of Blood-Separation Device
By replacing injection molding with laser sintering technology, a maker of centrifuges was able to streamline product design while reducing tooling and assembly costs
Corinne Litchfield

A manufacturer of laboratory centrifuges has developed a device that sediments and separates blood. The Rotomat incorporates a drum motor and six boxes and drip trays. The boxes have a complicated geometry and must withstand rotational speeds of 2000 rpm and acceleration forces of 1200 g. Andreas Hettich GmbH (Tuttlingen, Germany) determined that the use of conventional manufacturing technologies to make the device would require complex tooling and time-consuming assembly work. The firm decided to investigate other options. One that showed promise was laser sintering, offered as part of its e-Manufacturing technology by EOS GmbH (Krailling, Germany).

Laser sintering systems melt and solidify powders, which are deposited in successive layers to build a product. Plastic, metal, or sand powders can be used. The process has evolved over the years from a rapid prototyping and rapid tooling technology to a flexible batch-quantity manufacturing technique. Laser sintering is the core technology behind EOS GmbH’s e-Manufacturing platform, which allows companies to go directly from electronic data to fast, flexible, and cost-effective production.

Laser Sintering Versus Injection Molding

When it first evaluated laser sintering as an alternative production method, Hettich set as a baseline that it be at least as economical as injection molding. The evaluation included intensive testing of the laser-sintered boxes under production conditions. The results showed that the boxes, made of a polyamide 12 material, behaved similarly to those that were injection molded.

In other aspects, laser-sintered parts did more than simply match the performance of their injection-molded counterparts. In particular, the technology affords considerable design freedom. For example, internal structures can be easily realized, a capability that was used to its full advantage by design engineers at Hettich.

Conventional production methods require that box fixtures be molded separately. Consequently, additional tooling would have to designed and built, and the systems would need to be assembled. Laser sintering allowed the company to integrate fixtures into the box design. While the modified part was minimally more expensive to produce, the elimination of a new set of tooling and a reduction in assembly work more than made up for it. In addition, the new design improved functionality and added value to the product.

Laser sintering also enables parts production to be performed on demand. Design changes and product variations can be implemented quickly and at minimal cost. For example, the technology allows Hettich to offer different versions of the Rotomat to accommodate various blood bags.

By adapting its production methods to laser sintering technology, Hettich was able to design and manufacture a product with increased functionality without increasing costs, notes EOS GmbH.

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