Common steps to make an SLA model

1 May, 2001 By: Mark Huxley,Steven Weisberg Cadalyst

Common steps to make an SLA model
A summary of how the SLA process produces a rapid prototyping model
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1A solid CAD model is converted to an STL (stereolithography) file and sent to an RP service bureau for quote and subsequent build. The service bureau imports the STL into its RP software and properly orients it to use the superior surface finish of the positive z-axis. The service bureau may group this STL with others to maximize machine use.
2The service bureau may core out or honeycomb large solid areas, add supports for overhanging areas, and add vent holes and other elements as necessary.
3The RP program sections the STL file in the z-axis into slices about 0.005" thick. When the build starts in the SLA machine, the platen is at the maximum z-height. A laser traces the first section. To accomplish quicker, more accurate outlining and quick filling of each section, some machines now vary the diameter of their laser beams from about 0.005"—0.030".
4The machine lowers the platen about 0.005" . A wiper passes over the surface of the liquid to break the surface tension and ensure a smooth, even surface for the next section.
5The laser traces the next section. The machine repeats steps 4 and 5 until all sections are built.
6The machine attendant raises the platen, drains, wipes, and rinses the part as necessary, and may perform a final cure with UV light.
7The attendant removes the part from the platen and begins the finishing process by removing support structures from the part.
8Hand-finishing of the part is generally necessary. The level of finishing (as built, lightly sanded, paint ready, polished, etc.) will depend on its intended use.
A concept for a desktop stereo developed by Volan Design LLC for Dataplay Inc.'s CES debut. Left. CAD model of the assembly. Center. The STL output with a detailed view of a triangulated corner. Right. Finished prototype.

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