Intro to Rapid Prototyping
Rapid Prototyping is defined as a process to quickly fabricate a scale model of a part or assembly using a three-dimensional computer aided design (CAD) file. Spectrum Plastics Group offers several rapid prototyping methods, including Stereolithography (SLA), Laser Sintering (LS), Room Temperature Vulcanization (RTV) Rubber Molding and Urethane Castings, and Connex 3D Printing.
A 3-D CAD model is processed to create a file that can be interpreted by the stereolithography computer. This data is mathematically processed to yield a series of cross sections (layers). Next, computer-controlled mirrors direct an ultraviolet beam across the surface of a vat containing photo-curable liquid polymer. The laser traces the path of the cross section, changing the liquid into a solid, until a new layer is formed. This newly-formed layer is then lowered into the vat by an elevator, while a recoating and leveling system establishes the thickness for the next layer (from .002' to .006' thick depending on the SLA machine used). The part is built layer by layer, one on top of another, each adhering to the last, until a three dimensional part is formed.
Laser Sintering (LS)
Laser Sintering is a process that uses a laser beam to selectively melt a heated powder. It's done layer by layer, in usually .005'' (.125mm) layers. The process is analogous to Stereolithography, but instead of a vat of resin, there is an exchangeable frame filled with Nylon powder, yet in both processes the material is solidified using a laser beam.
PolyJet, or multi-jet modeling, is a 3D printing process where photopolymers are jetted on to a build platform, then parts are built up layer by layer. In this case, those layers can be as small as 16 microns, with 600x600 dpi.
RTV Rubber Molding and Urethane Casting
Room Temperature Vulcanization (RTV) molding is the fastest, most accurate, and least expensive way to create 1 - 100 duplicates of a prototype part, including small details on the original part.
The rubber mold is formed from a high level finish existing part or "pattern", A stereolithography (SLA) part is commonly used for the pattern. The SLA part is sometimes oversized to allow for shrink rate of the resin used. The SLA is surrounded by a surface to create the parting line to open the completed mold. A liquid RTV rubber is poured over the master pattern, including parting surface. After the rubber has solidified, the mold is split and the pattern is removed producing a two piece rubber tool.
Protogenic, a division of Spectrum Plastics Group, is available to meet your prototyping needs.