The center piece of ART's rapid prototyping capability is a 3D Systems SLA-250/40 stereolithography apparatus (SLA). With this equipment, we can produce plastic prototypes up to 10" x 10" x 10" in a single build. Most often deliveries occur in 3 to 5 days after receipt of electronic CAD data. These SLA prototypes are extremely useful in form, fit, and limited-functional testing. SLA models can also be used as masters for secondary operations, such as: silicone molding, investment casting, and sand casting. Should your project require larger models ( > 1000 cu. in.), we can either build those parts in smaller sections and epoxy them together upon completion or have them built on a larger SLA-500 available to us through a strategic relationship with another bureau. The SLA-500 build envelope is eight times larger than the SLA-250 envelope, at 20" x 20" x 24".

The Stereolithography Process

The stereolithography process produces exact replicas of computer solid models, within hours, by solidifying a liquid photo-curable resin, layer by layer, with a UV laser. Below is a schematic providing a general overview of the process.

A platform, mounted to a z-axis traversing elevator, is positioned within the vat of photo-curable resin. First a support structure is created to anchor the soon-to-be-built part to the platform and provide a flat surface for part building. A 3D solid model is "sliced" into horizontal cross-sections with thicknesses that correspond to the build layer thickness (typically 0.006 or 0.008" on the SLA-250). Each cross-section is then traced over the surface of the epoxy resin by the UV laser. The movements of the laser are controlled by stepper motor driven mirrors. After each layer is traced, the elevator is lowered into the vat to allow resin to cover the layer that was just solidified. The elevator then raises back up to a level that is one layer thickness below the previous layer. The sweeper blade moves across the vat removing any meniscus created by the part rising and the process starts all over with the next cross-section being traced on the surface of the resin. When all the cross-sections have been traced, the elevator raises the platform out of the resin allowing the solid model to drain until removed for post-processing.