Rapid Prototyping...this is what we used to call the additive manufacturing technology that is mostly called 3d printing today.
The initial primary value of Rapid Prototyping (RP) was the ability to quickly make plastic models of designs for fit, form and some function. RP was produced by expensive, highly specialized equipment that required controlled environments and trained operators.
Overtime, the industry evolved in the late 1990's to include an RP machine that would work in an engineers office, and this was the beginning of the currently popular 3d printing system. A system that can be operated by a general user and operate in a normal environment. Of course, the early 3d printers were sold to mostly engineers to be used in their offices and were actually still quite complex and expensive. For the history buffs, the first 3d printers were by a company called BPM (Ballestic Particle Modeling) based on an invention by one of my mentors, Bill Masters. BPM actually formalized the bifurcated of the industry into high-end RP systems and lower-end office printers.
The expiration of the early patents for RP, particularly FDM by Stratasys, launched a new wave of 3d printers by hobbyist and the current catayst for the popularity of 3d printing today.
The following is various bits of information on Rapid Prototyping to provide a context to the professional or industrial side of a fascinating industy.
Stereolithograpy is the founding technology for the 3d printing industry. SLA uses a UV laser to draw successive layers (cross-sections) on top of a photo-curable resin that solidifies when energized by the laser. While a simple approach to additive manufacturing, SLA is one of the most complicated processes since it requires mastery of chemistry, lasers and mechanics. Truly a beautiful masterpiece of innovation and engineering.
In the early 2000's, a company called Objet launched a new machine that merged the power of traditional SLA (photocurable resins) with ink-jet technologies. Over the decade, they evolved the technology to be one of the most powerful AM technologies on the market. Objet merged with Stratasys in 2013.
Below is a video on Stereolithography that was produced by a company that did a poor job of entering the RP market, but the video is decent. Skip to about 1:00 to get to the good stuff that shows the laser doing it's dance.
Below is the chapter on SLA from my book. It includes an overview, images and applications of the process for product development.
Since I mentioned Objet, the following is a reasonable video that clearly shows the process. Objet is a similar to SLA in that it is a chemical process that uses photo-curable resins. The primary difference is that Objet replaced the single laser beam with a bulb for UV energy and photo-masking.
FUSED DEPOSITION MODELING (FDM)
FDM is one of the pioneering technologies for RP. It is one of the simplest approaches to additive manufacturing, which is one of the reason it is the technology of choice for most 3d printers that are dominating the market (e.g Makerbot). It is essentially a hot glue gun that extrudes melted plastic. The following video is a well produced video on the technology.
SELECTIVE LASER SINTERING (SLS)
SLS is also a pioneering technology that evolved during the 1990's. The SLS process became a very useful technology to produce very durable, functional models that could help validate fit, form AND function of a new design.
SLS used powdered plastic and heat from a laser to sinter or melt the plastic together in successive layers. Using the powder allowed the materials to be more natural to the standard thermoplastic plastics, such as Nylon.