3D Printers

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 architecture, medical, automotive, education and consumer products.

The technology for printing physical 3D objects from digital data was first developed by Charles Hull in 1984. He named the technique as Stereolithography and obtained a patent for the technique in 1986.http://www.freepatentsonline.com/4575330.html After obtaining the patent, he founded 3D Systems and developed the first commercial 3D Printing machine. However the term “3D Printer” was not used by that time and the machine was called only as Stereolithography Apparatus. As the technology was very new, 3D Systems delivered the first version of the machine to only a few selected customers and based on their feedback, 3D Systems developed an improved version, named SLA-250, which was made available to the general public in 1988.http://dspace.mit.edu/bitstream/handle/1721.1/10954/35749974.pdf

While Stereolithography systems had become popular by the end of 1980s, other similar technologies such as Fused Deposition Modeling (FDM) and Selective Laser Sintering (SLS) were introduced. FDM was invented in 1988 by Scott Crump who founded Stratasys in the next year to commercialize the technology. Stratasys sold its first FDM-based machine, "3D Modeler", in 1992.http://www.fundinguniverse.com/company-histories/Stratasys-Inc-Company-History.html During the same year, DTM marketed SLS based systems.http://www.timecompression.com/columns/history-of-additive-fabrication-part-1

In 1993, Massachusetts Institute of Technology (MIT) patented another technology, named "3 Dimensional Printing techniques", which is similar to the inkjet technology used in 2D Printers. In 1995, Z Corporation obtained an exclusive license from MIT to use the technology and started developing 3D Printers based on 3DP technology.http://www.zcorp.com/en/Company/At-a-Glance/spage.aspx

In 1996, three major products, "Genisys" from Stratasys, "Actua 2100" from 3D Systems and "Z402" from Z Corporation, were introduced. It was only during this period, the term "3D Printer" was first used to refer rapid prototyping machines. During the late 1990s and early 2000s, several relatively low-cost 3D Printers came into the market.

In 2005, Z Corp. launched a breakthrough product, named Spectrum Z510, which was the first high definition color 3D Printer in the market.

Another breakthrough in 3D Printing occurred in 2006 with the initiation of an open source project, named Reprap, which was aimed at developing a self-replicating 3D printer. The first version of Reprap, which was released in 2008, can manufacture about 50 percent of its own parts. The second version of Reprap is currently under development.http://reprap.org/bin/view/Main/WebHome

The following are the predominant technologies used in 3D Printers.

1. Stereolithography (SL)
2. Fused Deposition Modeling (FDM)
3. Selective Laser Sintering (SLS)
4. 3 Dimensional Printing (3DP)
5. Polyjet
6. Polyjet Matrix

A Stereolithography machine consists of an UV (ultraviolet) laser, a build platform and a vat of liquid photopolymer. It works as follows. A software first divides the 3D CAD model into several thin layers and sends the data to the machine. The UV laser draws the first layer on the surface of photopolymer solidifying it onto the build platform. The platform is then lowered and recoated with the liquid photopolymer. The UV laser traces and solidifies the next layer. The process repeats until the complete three dimensional model is built.http://www.3dsystems.com/products/sla/tour/movtest.asp

Advantages: More accurate, Good feature detail, Smooth surface finish.

Disadvantages: Limited material options, Color models cannot be created.http://www.xpress3d.com/Processes.aspx

Fused Deposition Modeling technology uses thermoplastic material to build the 3D model. Similar to stereolithography, a software first converts the 3D CAD model into several thin layers. Then, the thermoplastic material is supplied to the extrusion head which is heated to melt the material. The extrusion head extrudes the thermoplastic material and deposits it layer by layer onto the built platform until the complete model is built.http://www.stratasys.com/

Advantages: More accurate, Greater material strength, Color models can be created,.

Disadvantages: Rough Surface finish.

Selective Laser Sintering technology works by using a CO2 (carbon dioxide) laser and a powder material. The powder material is placed over the build platform in several layers. Based on the 3D data, the CO2 laser binds the powder material layer by layer to build the model.http://www.materialise.com/materialise/view/en/91755-Selective+Laser+Sintering.html

Advantages: Greater material strength.

Disadvantages: Less accurate, Rough surface finish, Color models cannot be created.

The 3D printers based on this technology use a powder material and a liquid binder to build the model. It works similar to Selective Laser Sintering, but instead of using UV laser, it uses a liquid binder to bind the powder material. The liquid binder is sprayed through the inkjet printing heads similar to 2-D inkjet printing.http://www.zcorp.com/documents/108_3D%20Printing%20White%20Paper%20FINAL.pdf

Advantages: More accurate, High definition color models can be created.

Disadvantages: Less material strength, Rough surface finish, Less feature detail.

Polyjet and Ployjet Matrix are relatively new technologies which were introduced by Objet Geometries in 2000 and 2007 respectively. Polyjet technology works by jetting photopolymer material in ultra-thin layers onto a build platform. Polyjet matrix also allows simultaneous jetting of different types of materials. An UV light cures each layer immediately after it is jetted. Polyjet-based 3D Printers can produce more accurate models with layer thickness of about 16 microns.http://www.objet.com/Company/Company_Overview/

Advantages: More accurate, Smooth surface finish, Good feature detail, Color models can be created.

Disadvantages: Less material strength.

1. Stratasys - Fused Deposition Modeling
2. Z Corporation - 3 Dimensional Printing
3. 3D Systems - Stereolithography and Selective Laser Sinteriing
4. Objet Geometries - Polyjet & Ployjet matrix