The advantages and disadvantages of the most popular prototyping technologies are below:
1. Virtual Prototyping Virtual prototyping is a simulation of the part being designed created by 3D CAD software. It is ideal for early conceptualization because it allows parts to be designed, revised, virtually fitted together and tested using finite element analysis. The drawback is that it is entirely virtual, so going directly to high volume production from this point is very risky.
2. Fused deposition modeling (FDM) FDM is an additive fabrication process that melts solid thermoplastic and extrudes it through nozzles not much thicker than a human hair (minimum extrusion of approximately 0.01 inch). It is a relatively inexpensive process which produces durable, functional prototypes as well as low-volume production parts. It is more accurate and stronger than other additive technologies and can produce very complex (even unmanufacturable) geometries. Sometimes it suffers from stair-stepped surface finishes (although this can be resolved with post-processing via Ready Part) and only works with a range of materials.
3. Stereolithography Apparatus (SLA) SLA is an additive fabrication process that uses a laser to cure layers of photopolymer resin. The process is suitable for making concept models to support presentations or trade shows. It is a relatively inexpensive way to make a single part and produces a good surface finish. The drawback is that it only works with a very limited range of proprietary resins and produces a fragile end product whose dimensional stability suffers over time.
4. Selective Laser Sintering (SLS) SLS uses a laser to fuse powdered material. As is the case with SLA, SLS is suitable for making initial prototypes for demonstration purposes and is relatively inexpensive. SLS produces more durable parts than SLA, making it a good choice to test form and fit. Unfortunately, the parts produced are still too weak to be used for testing. As with other technologies, SLS works with a limited range of materials and the resulting parts have a rough finish.
5. Photo-polymer Jetting (PolyJet) PolyJet is similar to SLA, using computer controlled UV light to cure layers of photopolymer. As is the case with SLA, PolyJet is used primarily as a concept modeling process. PolyJet offers the same advantages as SLA, but typically costs less and produces a finer surface finish. When compared to SLA, PolyJet is more limited in the size of parts that can be created.
6. CNC Machining CNC machining uses traditional manufacturing equipment to cut parts from a solid block of material. The process is useful for demonstration parts through low volume production. It is as fast as the additive fabrication processes and produces parts comparable to injection molding. Unfortunately due to price, it is generally not well suited for production quantities in excess of hundreds of parts and is not a green alternative due to wasted material. Further, CNC cannot easily produce complex parts with internal cavities and undercuts.
The most popular prototyping technologies are available from Rapidpro .