| 3DP (THREE DIMENSIONAL PRINTING) |
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3DP(Three Dimensional Printing) is a form of additive manufacturing technology where a three dimensional object is created by successive layers of material. 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 3DP 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. While rapid prototyping dominates current uses, 3D printers offer tremendous potential for production applications as well. The technology also finds use in the jewellery, footwear, industrial design, architecture, automotive, aerospace, dental and medical industries. One variation of 3D printing consists of an inkjet printing system. Layers of a fine powder (plaster, corn starch, or resins) are selectively bonded by "printing" an adhesive from the inkjet printhead in the shape of each cross-section as determined by a CAD file. This technology is the only one that allows for the printing of full colour prototypes. It is also recognized as the fastest method. Alternately, these machines feed liquids, such as photopolymer, through an inkjet-type printhead to form each layer of the model. These Photopolymer Phase machines use an ultraviolet(UV) flood lamp mounted in the print head to cure each layer as it is deposited. Another approach is the 3D microfabrication technique of 2-photon photopolymerization with which ultra-small features can be made. 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. 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. Generally, the main considerations are speed, cost of the printed prototype, cost of the 3D printer, choice of materials, colour capabilities, etc. Unlike "traditional" additive systems such as stereolithography, 3D printing is optimized for speed, low cost, and ease-of-use, making it suitable for visualizing during the conceptual stages of engineering design when dimensional accuracy and mechanical strength of prototypes are less important. No toxic chemicals like those used in stereolithography are required, and minimal post printing finish work is needed; one need only brush off surrounding powder after the printing process. Bonded powder prints can be further strengthened by wax or thermoset polymer impregnation. Standard applications include design visualization, prototyping/CAD, metal casting, architecture, education, geospatial, healthcare, entertainment/retail, etc. Other applications would include reconstructing fossils in paleontology, replicating ancient and priceless artifacts in archaeology, reconstructing bones and body parts in forensic pathology and reconstructing heavily damaged evidence acquired from crime scene investigations. More recently, the use of 3D printing technology for artistic expression has been suggested. Artists have been using 3d printers in various ways. Advantages * On the fly modeling enables the creation of prototypes that closely emulate the mechanical properties of the target design; * Some technologies allow the combination of black and white rigid materials in order to create a range of grayscales suitable for consumer electronics and other applications; * Save time and cost by removing the need to design, print and 'glue together' separate model parts made with different materials in order to create a complete model. Ink Jet Printing Techniques Ink jet printing comes from the printer and plotter industry where the technique involves shooting tiny droplets of ink on paper to produce graphic images. RP ink jet techniques utilize ink jet technology to shoot droplets of liquid-to-solid compound and form a layer of an RP model. Common ink jet printing techniques includes Sanders ModelMaker™, Multi-Jet Modeling™, Z402 Ink Jet System™, and Three-Dimensional Printing, etc. We choose Multi-Jet Modeling and Three-Dimensional Printin for introduction as below. Multi-Jet Modeling * Fast. * Office-friendly: non-toxic materials, small footprint, low odor. * Simple operation: operates as a network printer in an office environment. * Models are primarily for appearance use. * Compared to SLS® and SLA, not as established. Multi-Jet Modeling™ uses a 96-element print head to deposit molten plastic for layering. The system is fast compared to most other RP techniques, and produces good appearance models with minimal operator effort. The main market that this system is targeted at is the engineering office where the system must be non-toxic, quiet, small, and with minimal odor. The system is illustrated below:  Three-Dimensional Printing * Binder is "printed" on unbound powder layer. * Without milling step, work plane can become successively skewed. * Not as established as SLA and SLS. Three-Dimensional Printing, developed by MIT and Soligen, Inc., is illustrated below. It is another technique based on the inkjet printing process. Binder is printed on a powder layer to selectively bind powder together for each layer.  |
