Rapid Prototyping Equipment Information
Rapid prototyping equipment builds models of products before they are mass produced for the marketplace. These physical prototypes can convey more complete information about a product early in the development cycle compared to virtual models. Parts that are fabricated relatively quickly can be tested early to identify problem areas requiring design iteration. Some rapid prototyping equipment is also referred to as additive manufacturing equipment or 3D printers. Computer numerical control (CNC) machining equipment can also be used for rapid prototyping, cutting away material from a block to form a part.
Rapid prototyping equipment is often part of a development process called computer-aided manufacturing (CAM), in which 3D models are created from computer-aided design (CAD) drawings. Rapid prototyping equipment reads CAD data and creates a sculptural object based on this information.
Rapid prototyping equipment can utilize a variety of 3D printing technologies to form objects, like those listed below.
Extrusion techniques include fused deposition modeling (FDM) and robocasting or direct ink writing (DIW).
- Fused deposition modeling (FDM) involves heating filaments of a material such as thermoplastic and dispensing it from a nozzle to form layers of the final object. The material hardens immediately after extrusion. FDM techniques can be quiet and reliable, although the process is often quite slow for some object geometries.
- Robocasting or direct ink writing (DIW) is similar to FDM in that a material is dispensed from a nozzle to form layers, but distinct in that the "ink" is often a ceramic slurry that requires the final object to undergo a sintering process to achieve mechanical strength.
Light polymerizing techniques include stereolithography (SLA) and digital light processing (DLP).
- Stereolithography (SLA) involves building object layers by focusing an ultraviolet laser onto a volume of photopolymer resin in the desired pattern, solidifying the resin due to its photosensitivity. SLA provides high accuracy and great surface finish in the finished product.
- Digital light processing (DLP) differs from SLA in that the source of light is a more conventional lamp as opposed to a laser. The light is reflected off a deformable mirror device (DMD) or through a liquid crystal panel to expose the photopolymer from below. DLP requires a smaller volume of photopolymer than SLA, and has the potential for faster production because an entire layer is exposed at once.
Powder bed techniques include powder bed and inkjet head 3D printing (3DP), electron-beam melting (EBM), selective laser melting (SLM), selective heat sintering (SHS), selective laser sintering (SLS), and direct metal laser sintering (DMLS).
- Laser sintering techniques are similar in concept to stereolithography methods. A laser is focused on a bed of powder material, fusing the powder in the desired pattern one layer at a time. Laser sintering allows material properties useful for real engineering applications, although the equipment required is typically complex and costly.
Direct metal laser sintering (DMLS) video.
Video credit: Stratasys Direct, Inc.
Lamination techniques include laminated object manufacturing (LOM) and selective deposition lamination (SDL).
- Laminated object manufacturing (LOM) involves cutting cross sections of the desired object out of a web material such as paper and layering each section with a plastic coating in between, acting as a bonding agent.
- Selective deposition lamination (SDL) is similar to the LOM method, but involves carefully depositing adhesive in higher densities in the areas that will become the part, and much lower densities in areas that will only serve as support. This allows rapid removal of supporting material when the part is complete.
Electron beam freeform fabrication (EBF) utilizes an electron beam to melt a metal wire and deposit the material on a metallic substrate, which then solidifies immediately. The technique reduces the need for surface finishing by creating objects that are very close to the final desired shape.