The PDMA Handbook of New Product Development

27.5. Overview of Commercial Rapid Prototyping Systems (High End)

The high-end rapid prototyping machines produce prototypes as close to the real part as possible without computer numerical control (CNC) machining them from the desired material for the project. The machines are best suited for service bureaus or large companies who can keep them running on a daily basis. This article does not contain a complete listing of every current rapid prototyping machine—only the major systems (by their unique process nature) are listed here.

27.5.1. Stereolithography (SLA)

Today one of the most common, highly recognized, and widely used RP processes is stereolithography. Introduced in the mid-1980s, it catapulted the rapid prototyping revolution forward. Stereolithography's strengths are in the accuracy of the part produced and its excellent surface finish. The SLA machine builds parts by passing a low-power laser beam, controlled by the computer, into a vat of a photo reactive resin. When the laser beam hit this resin, it solidifies. As each layer is printed, the build platform is lowered, a sweeper bar levels a new layer of uncured resin over the first, and the process is repeated until the part is complete. SLA's require "bridgework" constructed to keep unattached pieces from floating away. The pieces will become attached as further levels arc printed. This bridgework is very thin and is removed during the postprocessing cleanup. As with most rapid prototyping processes, the SLA machine ...