3D printing or Additive manufacturing is the process of making a three-dimensional object of just about any shape from a digital model. 3D printing is achieved by adding successive layers of material applied in different shapes. This is called an additive process, opposite of the subtractive process which is the traditional machining technique that relies on the removal of material by methods that include cutting or drilling.
Overview of 3D Printing
3D printing technology has been around since the 1980s, however, it wasn’t until the early in the past decade that the printers became widely available commercially. The first 3D printer was created by Chuck Hull from 3D Systems Corp. in 1984. There has been a large sales growth in 3D printers since the start of the twenty-first century which has caused the price of the machines to drop substantially.
The technology is used in several industries, including, jewelry, footwear, industrial design, architecture, engineering and construction, automotive, aerospace, dental and medical, education, geographic information systems and several others. There are three types of 3D printing, these include:
Fused Deposition Modeling (FDM)
Fused deposition modeling was developed by S. Scott Crump and was commercialized in 1990 by Stratasys. Since the patent expired, there has been a large open-source development community, as well as commercial and DIY variants that use this type of 3D printer.
FDM printers use a thermoplastic filament, which is heated to its melting point and then extruded, layer by layer, to create a three dimensional object. The printers use two kinds of materials, a modeling material, which makes up the finished object and a support material, which acts as a scaffolding to support the object while it is being printed.
Stereolithography (SLA) uses a vat of liquid ultraviolet curable photopolymer “resin” and an ultraviolet laser to build layers, one at a time, of the part being printed. For every layer, the laser beam traces a cross-section of the part pattern on the surface of the liquid resin. The ultraviolet laser light will then cure and solidify the pattern traced on the resin and join it to the layer below.
After the pattern has been traced, the SLA’s elevator platform descends by a distance equal to the thickness of a single layer. Then a resin-filled blade sweeps across the cross section of the part, recoating it with fresh material. On this new liquid surface, the next layer pattern is traced, this joins the previous layer. This is how a complete 3D part is formed. When they are finished, the parts are immersed in a chemical bath to be cleaned of excess resin and are subsequently cured in an ultraviolet oven.
Selective Laser Sintering (SLS)
SLS involves the use of a high power laser to fuse small particles of plastic, metal, ceramic or glass powders into a part that has a 3D shape. The laser fuses the powdered material by scanning cross-sections generated from a 3D digital description of the part on the surface of a powder bed. After each cross-section is scanned, the powder bed is lowered by one layer thickness, a new layer of material is applied on top, and the process is repeated until the part is finished.
The SLS machine uses a pulsed laser because the finished part density depends on peak laser power, rather than laser duration. The machine preheats the bulk powder material in the powder bed somewhat below its melting point, to make it easier for the laser to raise the temperature of the selected regions the rest of the way to the melting point.
Unlike FDM and SLA, SLS doesn’t require support structures because the part being constructed is surrounded by unsintered powder at all times. This allows for the construction of previously impossible geometries.
Uses for 3d printing
Manufacturing corporations and aerospace organizations have been able to save billions of dollars by using the 3D printing for building parts. 3D printing has saved lives as well.
The technology is impressive to say the least, not only because of the way 3D printers create items, but also because of the items that they are able to be create. Some of these items include:
Automotive engineers are using 3D printing to the save time required in prototyping the parts for vehicles.
3D printing has been used to print organs from a patient’s own cells. In the future patients may no longer have to wait for donors.
Last year, scientists from Princeton University created a bionic ear using a 3D printer. The reason for this experiment was to explore an effective way to merge electronics with tissue.
These are just a few of the endless possibilities the future holds for 3D printing technology.