3D printing


3D printing is a form of additive manufacturing technology where a three dimensional object is created by 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.

While rapid prototyping dominates current uses, 3D printers offer tremendous potential for production applications as well.[2] The technology also finds use in the jewellery, footwear, industrial design, architecture, automotive, aerospace, dental and medical industries.


Technologies

Previous means of producing a prototype typically took many hours, tools, and skilled labor. For example, after a new street light luminaire was digitally designed, drawings were sent to skilled craftspeople where the design on paper was painstakingly followed and a three-dimensional prototype was produced in wood by utilizing an entire shop full of expensive wood working machinery and tools. This typically was not a speedy process and costs of the skilled labor were not cheap, hence the need to develop a faster and cheaper process to produce prototypes. As an answer to this need, rapid prototyping was born.

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.

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 "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. FDM parts can be strengthened by wicking another metal into the part.

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Resolution

Resolution is given in layer thickness and X-Y resolution in dpi. Typical layer thickness is around 100 micrometres (0.1 mm), while X-Y resolution is comparable to that of laser printers. The particles (3D dots) are around 50 to 100 micrometres (0.05-0.1 mm) in diameter.

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Applications


An example of real object replication by means of 3D scanning and 3D printing: the gargoyle model on the left was digitally acquired by using a 3D scanner and the produced 3D data was processed using MeshLab. The resulting digital 3D model, shown on the laptop's screen, was used by a rapid prototyping machine to create a real resin replica of the original object

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.[7] Artists have been using 3d printers in various ways.[8]

3D printing technology is currently being studied by biotechnology firms and academia for possible use in tissue engineering applications where organs and body parts are built using inkjet techniques. Layers of living cells are deposited onto a gel medium and slowly built up to form three dimensional structures. Several terms have been used to refer to this field of research: Organ printing, bio-printing, and computer-aided tissue engineering among others.[9] 3D printing allows to manufacture a personalised hip replacement in one pass, with the ball permanently inside the socket, and even at current printing resolutions the unit will not require polishing.

The use of 3D scanning technologies allow the replication of real objects without the use of molding techniques, that in many cases can be more expensive, more difficult, or too invasive to be performed; particularly with precious or delicate cultural heritage artifacts.

Future applications may allow many of the familiar pieces of furniture in a contemporary home to be replaced by the combination of a 3D printer and a recycling unit. Clothing, crockery, cutlery and books can already all be printed on demand and recycled after use, meaning that wardrobes, washing machines, dishwashers, cupboards and bookshelves may eventually become redundant.

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RepRap

Main article: RepRap Project

RepRap is a project released under the GNU General Public License which aims to produce an open source self-replicating rapid prototyper; that is, a 3D printer which can print a copy of itself. It can currently only print plastic parts. Research is underway that will let it print circuit boards as well as details in metal. The creator said about the printer that "We want to make sure that everything is open, not just the design and the software you control it with, but the entire tool-chain, from the ground up." [10]

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Advantages

  1. On-the-fly modeling enables the creation of prototypes that closely emulate the mechanical properties of the target design

  2. 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

  3. 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.

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Equipment

A large number of competing technologies are available in the marketplace. As all are additive technologies, their main differences are found in the way layers are built to create parts. Some methods use melting or softening material to produce the layers (SLS, FDM) where others lay liquid materials thermodynamics sets that are cured with different technologies. In the case of lamination systems, thin layers are cut to shape and joined together.



A comparison of two ceramic art objects. The original was created by John Balistreri and then duplicated using a 3D Scanner and printed using 3D Ceramic Rapid Prototyping.


Prototyping technologies and their base materials

  1. 1.Selective laser sintering (SLS): Thermoplastics, metals, sand

  2. 2.Fused Deposition Modeling (FDM): Thermoplastics

  3. 3.Stereolithography (SL): Photopolymer

  4. 4.Lamination systems: Paper and plastic

  5. 5.Electron Beam Melting (EBM): Titanium alloys

  6. 6.3D Printing (3DP): Various materials

  7. 7.3D Ceramic Printing: Various clay and ceramic materials

In 2006, John Balistreri and others at Bowling Green State University began research into 3D Rapid Prototyping machines, creating printed ceramic art objects. This research has led to the invention of ceramic powders and binder systems that enable clay material to be printed from a computer model and then fired for the first time.

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See also


Design portal

  1. 3D microfabrication

  2. Additive manufacturing

  3. Contour Crafting

  4. Desktop manufacturing

  5. Digital fabricator

  6. Direct digital manufacturing

  7. Fused deposition modeling

  8. Instant manufacturing, also known as "direct manufacturing" or "on-demand manufacturing"

  9. List of emerging technologies

  10. Objet Geometries

  11. Rapid manufacturing

  12. Rapid prototyping

  13. Selective laser sintering

  14. Self-replicating machine

  15. Solid freeform fabrication

  16. Stereolithography

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References

  1. 1.^ See animation of layering

  2. 2.^ "Close-Up On Technology - 3D Printers Lead Growth of Rapid Prototyping - 08/04". Ptonline.com. Retrieved 2009-09-01.

  3. 3.^ Chee Kai Chua; Kah Fai Leong, Chu Sing Lim (2003). Rapid Prototyping. World Scientific. pp. 124. ISBN 9789812381170. Retrieved 2008-10-31.

  4. 4.^ "Cheaper avenue to 65 nm?". EETimes.com. Retrieved 2009-09-01.

  5. 5.^ "The World In 2008". Economist.com. 2007-11-15. Retrieved 2009-09-01.

  6. 6.^ "Bot generated title ->". Wohlers Associates<!. Retrieved 2009-09-01.

  7. 7.^ "Wall Street Journal" (PDF). Retrieved 2009-09-01.

  8. 8.^ Séquin, C. H. 2005. Rapid prototyping: a 3d visualization tool takes on sculpture and mathematical forms. Commun. ACM 48, 6 (Jun. 2005), 66-73. [1]

  9. 9.^ "ABC News: 'Organ Printing' Could Drastically Change Medicine". Abcnews.go.com. Retrieved 2009-09-01.

  10. 10.^ Hedquist, Ulrika (2008-04-08). "> Open source 3D printer copies itself". Computerworld. Retrieved 2009-09-01.

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Bibliography

  1. Objet geometries introduces PolyJet Matrix technology (2007)

  2. Grenda, E. (2006). The Most Important Commercial Rapid Prototyping Technologies at a Glance.

  3. Wright, Paul K. (2001). 21st Century manufacturing. New Jersey: Prentice-Hall Inc.

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External links


Wikimedia Commons has media related to: 3D printing

  1. Business Week: Printing in 3D Gets Practical

  2. Something Completely Different - 3D Printing

  3. Times Online article - Microtrends: 3D Printing

  4. Technical Articles on 3D printing

  5. 3D printer reshapes world of copying

  6. 3D Printing for the Masses

  7. 'Gadget printer' promises industrial revolution New Scientist

 
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