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Publication Date: 2005-Mar-02
Document File: 3 page(s) / 1M

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This paper relates to the manufacturing of plastic parts using the process of Laser Stereolithography.

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This paper relates to the manufacturing of plastic parts using the process of Laser Stereolithography.

The process of Laser Stereolithography is used to quickly fabricate models or parts. In the process, a bath of UV curable liquid photopolymer resin is exposed to a laser. The resin hardens or cures upon contact with the laser. In this way, three-dimensional objects are fabricated layer-by-layer. Because of the accuracy of lasers, objects of any shape and complexity can be fabricated.

Stereolithographic processes are material additive processes in contrast to milling machines which are material subtractive. Layers are fabricated in the X-Y axis plane while new layers are added in the Z-axis direction. The objects are fabricated on a platform that drops lower into the bath as layers are built up upon previous layers. When the build-up process is completed, excess resin is stripped off and final curing of the model part is done using an ultraviolet "oven."

As technology associated with stereolithography advances, the process is used to create smaller and thinner parts. The small parts may be fragile and often require a support structure to be built with the model parts. The support structure adds strength to the part as it is processed.

It is often useful to create parts that are highly transparent. For example, the model parts may be prototypes for an enclosure, and development engineers need to assess how parts packaged fit within the enclosure. As the model prototypes as well as the enclosed parts become smaller a higher degree of transparency is desired.

Some stages of the stereolithography process negatively impact the amount of transparency in the final model part. One problem is from laser "overcure" that is necessary during fabrication of the initial layers of the part. Overcuring results in a tran...