3D Printing is achieved using different printing methods, at the moment, the main printing technologies being used are:
In addition there are a few other less common printing technologies that include:
- Inkjet Based 3D Printing
- Three Dimensional Printing (3DP)
- Laminated Object Manufacturing
- Laser Engineered Net Shaping (LENS)
Thermoplastic Extrusion is one of the most widely used 3D Printing (additive fabrication) methods, this method is also known as Fused Deposition Modeling (FDM), Fused Filament Fabrication (FFF) or Melted Extrusion Modeling.
This method of printing uses a plastic material (from a reel) which is fed into a extrusion nozzle, the extrusion nozzle is heated so as to melt the plastic material. The melted material is then dropped in very small beads onto a stage (flat board where the model is built), as the plastic leaves the heated nozzle, it soon cools, hardens and bonds to the layer it has been placed onto. One layer is completed before the printer starts the next layer, thus gradually building up a model (layer-by-layer).
One of the problems with this method of 3D Printing is warping of the models, many 3D Printers use a heated stage to help to prevent warping, whilst some of the more expensive / professional systems encapsulate the whole mechanism within a temperature controlled chamber.
Several thermoplastic materials are used, including PLA (Polylactic Acid), ABS (Acrylonitrile butadiene styrene) and PVA (Polyvinyl Alcohol Plastic). More information can be found on our Printer Materials page.
This method of printing is fairly quiet, and ideally suited for production of small plastic models (it can be very time consuming to produce a large model).
The finish of models produced using Themoplastic Extrusion varies depending on the printer, the quality of this printing technology has improved in recent years, but it isn't as good as models printed using sterolithography.
Stereolithography is a very popular form of 3D Printing also known as optical fabrication, photo-solidification, solid free-form fabrication and solid imaging.
This method of printing typically involves the use of a laser and a vat of liquid photopolymer (resin). The laser is traced onto the surface of the vat of resin, as the laser hits the resin it quickly solidifies. A single layer is completed before the printer moves to the next layer, this is achieved by lowering the model (layers built so far) down into the resin, thus exposing a single layer of resin above the model, the laser then works on this layer of resin before moving onto the next, thus gradually building up the 3D model.
Some of the latest methods of stereolithography use a LCD (liquid crystal display) or DMD (deformable mirror device) light source to harden the photopolymer liquid, instead of a laser, this is helping to reduce the cost of this type of printer.
One of the main advantages of this method of printing is the quality of the 3D models that are produced are very accurate and have an excellent finish. This method of printing is also much faster that the thermoplastic printing method, and some very large objects can be produced using this method of printing (there are some very large Stereolithography printers). In addition there is a wide range of materials available allowing production of many different types of object.
However, the cost of stereolithography printers is still high, as are the resins, and working with the liquid materials can be a lot messier that using reels of thermoplastic material.
More information about Stereolithography can be found at: https://en.wikipedia.org/wiki/Stereolithography
Laser Sintering also known as Selective Laser Sintering (SLS) is a method of additive printing that uses a powder material and laser to sinter (bond) the powder.
The procedure involves a piston that delivers the powder by moving upwards, each incremental movement upwards delivers a measured amount of powder to produce a layer of the object. The powder is then spread by a roller across the surface of a build cylinder. This build cylinder also contains a piston that moves downwards each time a new layer is added. A laser is used on the new layer of powder, this laser selectively targets only the areas of the powder that require sintering (bonding), the heat of the laser bonds the powder forming a solid layer. The model is thus fabricated layer-by-layer until complete, at which time is is elevated from the build cylinder where any excess powder is brushed away. The mechanism is contained within a temperature controlled fabrication chamber to allow the laser to operate more efficiently thus producing 3D models at a greater speed.
A major benefit of Laser Sintering technology is it allows printers to be created that will work with various types of powders, thus high quality models can be fabricated using plastics, metals, ceramic or glass powders. Although, to perform laser sintering with metals requires much higher powered lasers to those used for plastic laser sintering, however it is possible to use a metal powder coated in plastic to allow a lower powered laser to be used.
Some of the disadvantages of Laser Sintering include the cost which can be quite prohibitive, the complexity of the technology, and the length of time it can take for a model to cool down after being produced, in some cases it can take a few days for large objects to cool.
More information about Laser Sintering can be found at: https://en.wikipedia.org/wiki/Selective_laser_sintering