3D printing is a form of additive manufacturing technology where a three dimensional object is created by laying down successive layers of material[1]. 3D printers are generally faster, more affordable and easier to use than other additive manufacturing technologies. 3D printers offer product developers the ability to print parts and assemblies made of several materials with different mechanical and physical properties in a single build process. Advanced 3D printing technologies yield models that closely emulate the look, feel and functionality of product prototypes.
In recent years 3D printers have become financially accessible to small- and medium-sized business, thereby taking prototyping out of the heavy industry and into the office environment. It is now also possible to simultaneously deposit different types of materials.
3D printers offer tremendous potential for production applications as well.[2] The technology also finds use in the jewellery, footwear, industrial design, architecture, engineering and construction (AEC), automotive, aerospace, dental and medical industries.
Additive Manufacturing :
Additive manufacturing (AM) is defined by ASTM as the "process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies. Synonyms: additive fabrication, additive processes, additive techniques, additive layer manufacturing, layer manufacturing and freeform fabrication"[1]
The term Additive manufacturing describes technologies which can be used anywhere throughout the product life cycle from pre-production (i.e. rapid prototyping) to full scale production (also known as rapid manufacturing) and even for tooling applications or post production customisation.
Technologies :
One variation of 3D printing consists of an inkjet printing system used by Z Corporation. A 3D CAD file is imported into the software. The software slices the file into thin cross-sectional slices, which are fed into the 3D printer. The printer creates the model one layer at a time by spreading a layer of powder (plaster, or resins) and inkjet printing a binder in the cross-section of the part. The process is repeated until every layer is printed. This technology is the only one that allows for the printing of full colour prototypes. It is also recognized as the fastest method.
Alternately, in DLP, or Digital Light Projection, a liquid polymer is exposed to light from a DLP projector under safelight conditions. The exposed liquid polymer hardens. The build plate then moves down in small increments and the liquid polymer is again exposed to light. The process repeats until the model is built. The liquid polymer is then drained from the vat, leaving the solid model. The ZBuilder Ultra is an example of a DLP rapid prototyping system.
Fused deposition modeling (FDM), a technology developed by Stratasys[3] that is used in traditional rapid prototyping, uses a nozzle to deposit molten polymer onto a support structure, layer by layer.
Another approach is selective fusing of print media in a granular bed. In this variation, the unfused media serves to support overhangs and thin walls in the part being produced, reducing the need for auxiliary temporary supports for the workpiece. Typically a laser is used to sinter the media and form the solid. Examples of this are SLS (Selective laser sintering) and DMLS (Direct Metal Laser Sintering), using metals.
Finally, ultra-small features may be made by the 3D microfabrication technique of 2-photon photopolymerization. In this approach, the desired 3D object is traced out in a block of gel by a focused laser. The gel is cured to a solid only in the places where the laser was focused, due to the nonlinear nature of photoexcitation, and then the remaining gel is washed away. Feature sizes of under 100 nm are easily produced, as well as complex structures such as moving and interlocked parts.[4]
Each technology has its advantages and drawbacks, and consequently some companies offer a choice between powder and polymer as the material from which the object emerges.[5]Generally, the main considerations are speed, cost of the printed prototype, cost of the 3D printer, choice of materials, colour capabilities, etc.[6]
Unlike stereolithography, inkjet 3D printing is optimized for speed, low cost, and ease-of-use, making it suitable for visualizing during the conceptual stages of engineering design through to early-stage functional testing. No toxic chemicals like those used in stereolithography are required, and minimal post printing finish work is needed; one need only to use the printer itself to blow off surrounding powder after the printing process. Bonded powder prints can be further strengthened by wax or thermoset polymer impregnation. FDM parts can be strengthened by wicking another metal into the part.
The democratization of 3D printing is evolving in two streams, firstly with DIY 3D Printers such as BotMill, MakerBot and RepRap for home 'desktop manufacturing'. The second stream is through online services such as Shapeways or Sculpteo that allow users to upload their designs to have them 3D printed in a wide range of materials (currently 20 material options) and shipped worldwide. The creation of tools that enable 3D printing without the direct use of CAD are also currently being implemented.
Below is the video of MakerBot - A 3D printing robot .
The Future :
According to Neil G
ershenfeld ,
who runs MIT's Center for Bits and Atoms,
foresees a time when computers will upgrade from PCs to PFs, or personal fabricators. His book on FAB at home reveals a lot on this topic.
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