There are three major 3D Printing technologies that comprise the bulk of the current market for small desktop/deskside printers. They are Fused Deposition Modeling (FDM), Stereolithography (SLA), and Selective Laser Sintering (SLS). Later there may be some pictures of three tanks printed using these three technologies but first a little more introduction.
FDM is the technology that most people will have seen and/or heard about as it is used in most printers that people are buying for personal use. Plastic filament in either 1.75, 2.85, or 3mm diameters are fed into a heated nozzle that extrudes the plastic in a thin line. The layer of plastic extruded can be a variety of thicknesses but the range of .1mm to .2mm, or 100 microns to 200 microns, is the most common. The printer builds a solid object one layer at a time with either the build platform, usually surfaced with a piece of glass, falling or the extruder assembly with the nozzle rising. Much more here!
SLA uses Ultra Violet light focused on a liquid resin causing it to harden with a similar result as described above as the model is built one layer at a time...but generally on a platform that is rising from a vat of the resin! The UV light is projected onto the bottom of the vat, the build platform starts the print touching the bottom of the vat, and with each layer the build platform is raised. The Form 1, a very popular SLA printer, is an example for this printing technology. Much more here!
SLS has been around long enough for patents to start to expire leading to printers of its ilk starting to come down in price and hence be seen more often. It uses a laser to sinter a powder, a layer at a time (there is a theme here), into a 3D object. Sintering, btw, is heating and compressing something but not melting it. In this process a powdered material is delivered layer by layer to the build platform where a laser does the sintering. The build platform lowers as each layer is sintered. Much more here!
FDM and SLA both share a common characteristic in that the object being printed will have rely on what are called support structures to print elements of the model that would otherwise be "printed on air". More about this later. SLS does not need support structures because the powder from each layer remains and provides that support. It can print crazy geometries and the part comes off the printer clean. I have never seen an SLS printer in person but it sounds kinda messy even if the part is clean. Maybe not as messy as an SLA printer with its resin but messy. Still if the price comes down I may have to have one!
There is one other printer technology worth mentioning and that is multi jet. Shapeways offers this as their Frosted Detail Plastic which is one of their more expensive offerings. It prints at a layer thickness of less than 20 microns and does so with one jet spraying a wax support material and another the actual plastic for the model. I have not done a print using this technology due to the cost but the pictures that I have seen are impressive. All the advantages of the SLS printer but with the look of an SLA print but at even better detail. Yours for $20000!
The 3D printing space is rapidly evolving with new printers and printing technology hitting the market all the time. This article was probably out of date before I pressed save!