SLA – Stereolithography apparatus
Stereolithography (SLA) was the first commercially exploited method on the market, the patent is from 1985. GT Prototyper has worked with SLA-technique since 1996. Since 2000 we have three SLA-systems installed, all from 3D-Systems. SLA is the most accurate method on the market for additive manufacturing, deviations are ever so rarely more than 0.10 mm. SLA-models are the given choice as patter in a succeeding process (e.g. Vacuumcasting, plastercasting). SLA-materials of today (epoxy) are quite durable, issues with sensibility to UV and humidity belongs to the past. Temperature resistance is however quite reduced. Prices are mainly affected by height and volume. Time-consumption per part is not linear, therefore it does not take twice as long time to build two parts instead of one.
SLA-technique works on same principles as all AM-methods starting with a software that slices the CAD-model in to thin layers (normally 0,1 mm). Inside the generated boundaries a raster is created, the raster is then controlling the laserspot. Before a build is started, a platform is placed just beneath the surface in a container consisting of UV-curing, floating epoxy. The laser is then exposing the areas described in the slicefile and there the epoxy will cure. When one layer is cured the platform is lowered by one layerthickness and the curing of next layer takes place. The procedure goes on until the whole model is cured. The first ten millimeters consist of supportstructure, this to enable release of the parts from the platform. After parts are taken out of the machine, and the support-structure has been removed, a cleaning and rinsing procedure takes place. Parts are then postcured in an UV-oven, finished, blastered and measured before delivery.
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