Three dimensional printing

THREE DIMENSIONAL PRINTING

Shreya Kumar

Electronics and electrical communication

PEC University of Technology

Sector 12, Chandigarh (India)

[e-mail]

ABSTRACT

Three dimensional printing or additive printing uses additives to form solid 3D objects of virtually any shape from a digital model. This is achieved using specially formulated additives, such as plastics, that are formed into successive layers of material typically laid down on a platform in different shapes. 3D printing is uniquely distinct from a more traditional 3D sculpting technique, which relies on the removal of layers (subtractive manufacturing) to produce a three-dimensional object. 3D printers work like inkjet printers. Instead of ink, 3D printers deposit successive layers to create a physical object from the data file.

KEYWORDS

3D printing, additive manufacturing, stereo lithography

1. 
   INTRODUCTION
   

3D printing is a form of additive manufacturing technology where a three dimensional object is created by laying down successive layers of material. It is also known as rapid prototyping, is a mechanized method whereby 3D objects are quickly made on a reasonably sized machine connected to a computer containing blueprints for the object. The 3D printing concept of custom manufacturing is exciting to nearly everyone. This revolutionary method for creating 3D models with the use of inkjet technology saves time and cost by eliminating the need to design; print and glue together separate model parts. Hence, creation of a complete model

Mentor: Sukhwinder Singh

Electronics and electrical communication

PEC University of Technology

Sector 12, Chandigarh (India)

[e-mail]

of 3D image is possible with the translation of code into a visible pattern. Typical 3D Printer 3D Printers are machines that produce physical 3D models from digital data by printing layer by layer. It can make physical models of objects either designed with a CAD program or scanned with a 3D Scanner. It is used in a variety of industries including jewelry, footwear, industrial design, architecture, aerospace, dental and medical industries, education and automotive industries.

2. 
   HISTORY
   

The first published account of a printed solid model was made by Hideo Kodama of Nagoya Municipal Industrial ResearchInstitute in 1982. The first working 3D printer was created in 1984 by Charles W. Hull of 3D Systems Corp. In 1992 the first SLA machine is produced by 3D systems. The machine’s process involves a UV laser solidifying photopolymer, a liquid with the viscosity and colour of honey that makes three dimensional parts layer by layer. In 1999, the first lab-grown organ is implanted in young patients where urinary bladder augmentation using 3-D synthetic scaffold coated with patient’s own cells. In 2002, a working 3D kidney is engineered at the Wake Forest Institute for Regenerative medicines.[1]

Hence, various advancements occur by the development of prosthetics, bioprinter to print blood vessels, aircrafts, and guns.

3. 
   HOW PRINTER WORKS
   

Stereo lithographic 3D printers (known as SLAs or stereo lithography apparatus) position a perforated platform just below the surface of a vat of liquid photo curable polymer. A UV laser beam then traces the first slice of an object on the surface of this liquid, causing a very thin layer of photopolymer to harden. The perforated platform is then lowered very slightly and another slice is traced out and hardened by the laser. Another slice is then created, and then another, until a complete object has been printed and can be removed from the vat of photopolymer, drained of excess liquid, and cured.

Fused deposition modeling - Here a hot thermoplastic is extruded from a temperature-controlled print head to produce fairly robust objects to a high degree of accuracy. The model to be manufactured is built up a layer at a time. A layer of powder is automatically deposited in the model tray. The print head then applies resin in the shape of the model. The layer dries solid almost immediately. The model tray then moves down the distance of a layer and another layer of power is deposited in position, in the model tray. The print head again applies resin in the shape of the model, binding it to the first layer. This sequence occurs one layer at a time until the model is complete.

3D PRINTING METHODS

Stereo lithography (SLA)

3D Systems explains the process of Stereo lithography

The first commercially available 3D printer (not called a 3D printer back then) used the stereo lithography (SLA) method. This was invented in 1986 by Charles Hull, who also at the time founded the company, 3D Systems. A SLA 3D printer works by concentrating a beam of ultraviolet light focused onto the surface of a vat filled with liquid photo curable resin. The UV laser beam draws out the 3D model one thin layer at a time, hardening that “slice” of the eventual 3D model as the light hits the resin. Slice after slice is created, with each one bonded to the other, and next thing you know you have a full, extremely high-resolution three dimensional model lifted out of the vat. Unused resin is reusable for the next job.

Fused Deposition Modeling (FDM)

Fused Deposition Modeling at a trade show.

Also invented in the late 1980s, by Scott Crump, was Fused Deposition Modeling (FDM) technology. With patent in hand, he and his wife founded Stratasys in 1988. With FDM, the object is produced by extruding a stream of melted thermoplastic material to form layers. Each layer stacks on top of and fuses with the previous layer as the material hardens almost immediately after leaving the extrusion nozzle. It is one of the less expensive 3D printing methods. Most FDM printers print with ABS plastic (think Lego), as well as PLA (Polylactic acid), a biodegradable polymer, which is produced from organic material.

The actual term “Fused Deposition Modeling” and its abbreviation “FDM” are trademarked by Stratasys. RepRap uses a similar process, but has called it “Fused Filament Fabrication” (FFF), so as to not step on the trademark. With FFF, the material is fed via filament from a spool of the material.

Selective Laser Sintering (SLS)

3D Systems demonstrates the SinterStation Pro SLS 3D printer

The 1980s were big for inventing 3D printing technologies. Not only were SLA and FDM invented and patented then, but so was Selective Laser Sintering (SLS), by Carl Deckard and colleagues at the University of Texas in Austin. SLS works similarly to SLA, but instead of liquid photopolymer in a vat, you’ll find powdered materials, such as polystyrene, ceramics, glass, nylon, and metals including steel, titanium, aluminum, and silver. When the laser hits the powder, the powder is fused at that point (sintered). All unsintered powder remains as is, and becomes a support structure for the object. The lack of necessity for any support structure with SLS is an advantage over FDM/FFF and SLA — there’s none to remove after the model is complete, and no extra waste was created. All unused powder can be used for the next printing.

PolyJet photopolymer

Objet developed this technology: much like a traditional inkjet printer deposits ink, a photopolymer liquid is precisely jetted out and then hardened with a UV light. The layers are stacked successively. The technology allows for various materials and colors to be incorporated into single prints, and at high resolutions.

Syringe Extrusion

Almost any material that has a creamy viscosity can be used in 3D printers equipped with syringe extruders. This includes materials like clay, cement, silicone, and Play-Doh. Certain foods like chocolate, frosting, and cheese can also be printed with these systems. The syringe may or may not need to be heated, depending on the material; chocolate may need to be kept warm while silicone can be kept at room temperature.

Other Methods

There are other variants of these technologies. For example there is Selective Laser Melting (SLM), which is like SLS but it fully melts the powder rather than just fusing the powder granules at a lower temperature. This is similar to Electron Beam Melting (EBM) which uses an electron beam instead of a UV laser. And then there is a completely different technology called Laminated Object Manufacturing (LOM), where layers of adhesive-coated paper, plastic, or metal laminates are successively glued together and cut to shape with a knife or laser cutter.

3D Printing is a Game Changer

Instantly printing parts and entire products, anywhere in the world, is a game changer. But it doesn’t stop there. 3D printing will affect almost every aspect of industry and our personal lives.

Medicine will forever be changed as new bioprinters actually print human tissue for both pharmaceutical testing and eventually entire organs and bones.

Architecture and construction are changing as well. Now, 3D-printed models of complex architectural drawings are created quickly and inexpensively, rather than the expensive and time-consuming process of handcrafting models out of cardboard. And experimental, massive 3D printers are printing concrete structures, with the goal of someday creating entire buildings with a 3D printer.

Art is already forever changed. Digital artists are creating magnificent pieces that seem almost impossible to have been made by traditional methods. From sculptures to light fixtures, beautiful objects no longer need to be handcrafted, just designed on a computer.

And there are developments where you least expect them: for example, archeologists can 3D scan priceless and delicate artifacts, and then print copies of them so they can handle them without fear of breakage. Replicas can be easily made and distributed to other research facilities or museums. It has been used to create a full-size reproduction of King Tutankhamun’s mummy and to repair Rodin’s sculpture, The Thinker.

4. 
   FUTURE OF 3D PRINTING
   

A Belgian company, LayerWise, used 3D printing to create a jawbone that was recently implanted into an 83-year-old woman. An Australian company, Inventech, has created what they call their 3D BioPrinters to print tissue structures using human tissue. And Bespoke Innovations is using 3D printing to create prosthetic limb castings.

This amazing technology can also be used for on-demand printing of spare parts--something the U.S. military is already doing in the field. Knowing this, it is not hard to see that in the future, a manufacturer could sell a machine or system to a company, and as part of their maintenance and support contract they can put their 3D printer on-site with the licensed software to print replacement parts as needed. In the near future we'll even see 3D printers have the ability to print two or more different materials at the same time, which will unlock many more applications since numerous goods consist of more than one material.

3D printing will definitely become more commonplace in the coming years thanks to its many benefits, including the ability to print the complete part without assembly and the ability to print complex inner structures too difficult to be machined. Additionally, the entire process produces much less waste than traditional manufacturing where large amounts of material have to be trimmed away from the usable part. Because this technology is growing so fast and can do so much, it is something that manufacturers of all sizes can no longer ignore.

5. 
   REFERNCES
   

[1]http://www.redorbit.com/education/reference_library/general-2/history-of/1112953506/the-history-of-3d-printing/

[2] Sherman, Lilli Manolis. "3D Printers Lead Growth of Rapid Prototyping (Plastics Technology, August 2004)". Retrieved 2012-01-31.

[3]3D Printing of Embedded Optical Elements for Interactive Devices Willis, K. D.D., Brockmeyer, E., Hudson, S. E., and Poupyrev, I. Printed Optics: 3D Printing of Embedded Optical Elements for Interactive Devices. In Proc. ACM UIST (2012).

[4]http://www.stratasys.com/applications