The Various Ways of Prototyping

Stereolithography (SLA): The SLA process was coined in 1986 by Charles W. Hall.  SLA is the method of layering curable materials in a successive form to create an object. Photopolymer resin sits in a tub as a ultraviolet laser.  The laser builds up layer after layer of this resin until the desired form is completely traced. The drawback of SLA printing is time.  Depending on the complexity of the part, the manufacturing time varies accordingly.

Selective Laser Sintering (SLS):  The SLS process uses a high-powered carbon-dioxide laser to selectively fuse pieces of plastic, metal, ceramics, or glass into a three dimension form.  The material lays in a tub underneath the laser.  With the input to the SLS system being a CAD file, the file is then broken down into layers, determined by the complexity of the part.  This process is well known for being stronger and more rigid that similar prototyping methods.  For instance, one SLS produced part can be a finished product if desired. 

Fused deposition modeling (FDM): The FDM process is one that most are familiar with.  I have been using FDM machines since high-school.  These machines are relatively cheaper than its other competitors.  The FDM process begins with a CAD file, then the FDM machine does the rest.  In Fused deposition modeling, the printer head lays out a molten bead of plastic.  After these rows of liquid plastic are 'printed', the machine rebuilds specific areas of the piece until the desired shape is complete.  Although these machines are cheaper, the main drawback is with this process is time.  The fact that the FDM machine needs to repetitively layer up .005" beads of plastic means extensive manufacturing time. 

Laminated Object Manufacturing (LOM):  The LOM process is one of the cheaper processes used in todays prototyping world.  The LOM process uses paper which is laser-cut or machine cut to the desired dimensions.  Each individual piece is cut to its specific dimension by input provided by CAD data.  Paper models, once completed, have similar finishing properties as wood, which allows this process to be a final output level of manufacturing.