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First Machine Generation

“Although very intricate parts produced by rapid prototyping equipment are now common, the first parts out of these types of systems required a good deal of faith that improvements would occur. Shown are three early parts from different experimental systems. The Housholder part was made from an embodiment that included a grid for separating mold material (concrete and water) from casting material (dry concrete). The Herbert part was created in August 1979. It is not known exactly when the Kodama and Housholder parts were created[1].”

Three early rapid prototyping parts; from left to right by Kodama, Herbert, and Housholder.[1].

Commercial Rapid prototyping technology exists since 1987[2]. The first machine was engineered by 3D Systems (Rock Hill, SC) and created three-dimensional shapes through layered UV curing of a photosensitive resin. The SLA-1 was the first commercially available additive process machine in the world. The technology was coined “Stereo Lithographic Apparatus” (SLA) and represents together with “Selective Laser Sintering” (SLS) the most prominent RP technologies for high quality, large scale[3] models with a broad selection of available materials. Several other companies as NTT Data CMET, Sony/D-MEC and EOS, Germany were developing their own applications of the stereolithographic process in the following years. The successive development of acrylic and epoxy resins was enhancing the material properties of the first models.

SLA Printer by 3D Systems, CAL

1991 saw the arrival of three new additive technologies: “Fused Deposition Modeling (FDM)[4] from Stratasys (Eden Prairie, MN), Solid Ground Curing (SGC)[5] from Cubital and Laminated Object Manufacturing (LOM)[6] from Helisys.”[7]

o FDM is an additive layered build system that uses a plastic filament or metal wire that is unwound from a coil and supplies material to an extrusion nozzle which can turn on and off the flow. The controlled extrusion head deposits very thin beads of material onto the build platform to form the first layer. The platform is maintained at a lower temperature, so that the thermoplastic quickly hardens. No post curing is required and the FDM technique also enables the designer to create functional snap fit parts without the need for secondary processes. After the platform lowers, the extrusion head deposits a second layer upon the first. Supports are built along the way, fastened to the part either with a second, weaker material or with a perforated junction. [8]

o The SGC process uses photosensitive resin hardened in layers as with the Stereolithography (SLA) process. However, in contrast to SLA, the SGC process is considered a high-throughput production process. The high throughput is achieved by hardening each layer of photosensitive resin at once. Many parts can be created at once because of the large work space and the fact that a milling step maintains vertical accuracy. [9]

o In the LOM technique profiles of object cross sections are cut from paper or other material using a laser. The paper is unwound from a feed roll onto the stack and first bonded to the previous layer using a heated roller which melts a plastic coating on the bottom side of the paper. The profiles are then traced by an optics system that is mounted to an X-Y stage. After cutting of the layer is complete, excess paper is cut away to separate the layer from the web. Waste paper is wound on a take-up roll. [10]

A year later Selective Laser Sintering (SLS) became available on the market. The technology was originally developed at the University of Texas and patented[11] in 1989 by Carl Deckard and commercialized by DTM Corporation, now 3D Systems.

o The SLS rapid prototyping process uses the heat of a CO2 laser to “sinter” or melt powdered thermoplastic materials or thermoplastic binders in high temperature resistant powdered materials such as ceramics and metals in layers of 0.1mm-0.15mm.  The Higher powered (>50W) CO2 lasers is guided across the part bed by a scanning system and “selectively” sinters or melts the material based on cross-sectional slice information of the 3D CAD data file.  The part or parts are built in an atmosphere that controls the thermal distribution and thus requires very little laser power to sinter the material.  The powder in the build chamber acts as a support for the part during fabrication and thus no additional support structure is required.  SLS is able to produce parts with tolerances and detail similar to SLA, but with the added advantage of strength.

Until 1993 the RP technology focus lay in the functional testing and product design development through abstracted models, with a limited functionality and material performance. With the arrival of the Direct Shell Production[12] (DSPC) that generated a ceramic casting pattern for investment casting the models became a generic physical component in the actual manufacturing process.

o Direct Shell Production Casting (DSPC) fabricates ceramic shells (molds) that can be used to cast metal parts. A DSPC system consists of a shell design unit (SDU) and a shell production unit (SPU). A CAD file containing the data of the designed part is transferred to the SDU. The operator of the SDU, which is essentially a graphics workstation, then designs the ceramic mold by adding the gating system to the data in the CAD file. This updated CAD file is then converted into a cavity file. The ceramic mold can then be automatically fabricated from the cavity file as many times as needed by the SPU. The ceramic mold is built in layers by slicing the model into cross-sections, spreading a fine layer of fine alumina powder with a roller mechanism, and depositing a liquid resinous binder in regions corresponding to the cross-section of the mold with a multi-jet print head moving across the section. This process is repeated for each layer until the entire mold is built. The binder that is deposited for each layer penetrates the pores between the powder particles resulting in the layers adhering to each other. The mold can contain an integral ceramic core in order to produce a hollow metal part. Once the mold is built, the excess powder is cleaned away and the mold is fired.

Military CRT housing in 356 aluminum, size appr. 127mm x 50.8mm, images by www.soligen.com

The introduction of this additive fabrication technique marked the beginning of the Rapid Tooling Process. Fraunhofer Allianz described the main objectives for Rapid Tooling as followed: “Producing functional molds, mold inserts and tools extremely rapidly and efficiently for short-term manufacturing of small and medium-sized lots made of polymer, metal or ceramic with features similar to or consistent with a series by employing high-performance Rapid processes.” [13] The materialized model was synchronized with the end product in scale and contained an active role in the actual materialization process.


[1] Beaman, Prof. Joseph J. . “Chp. 3: Technology.” World Technology Evaluation Center: Welcome. 28 Aug. 2008 <http://www.wtec.org/loyola/rp/03_01.htm#F03_12a>.

[2] First outline of the technique was patented by Hull, Charles. “Apparatus for production of three-dimensional objects by stereolithography.” Google. 11 Mar. 1986. 26 Aug. 2008 <http://www.google.com/patents?id=y

[3] max 2100×680x800mm (Mammoth SLA, 3D Systems)

[4] Crump, Scott S.. “Apparatus and method for creating three-dimensional objects.” Patent number: 5121329. 30 Oct. 1989. 28 Aug. 2008 <http://www.google.com/patents?id=VPApAAAAEBAJ&dq=5121329>.

[5] Pomerantz, Itzchak , Joseph Cohen-Sabban, Avigdor Bieber, Josef Kamir, Mathew Katz, and Michael Nagler. “Three dimensional modelling apparatus .” Patent number: 4961154. 2 Oct. 1990. 28 Aug. 2008 <http://www.google.com/patents?id=2ZYkAAAAEBAJ&dq=4961154>.

[6] Kinzie, Norman. “Method and apparatus for constructing a three-dimensional surface of predetermined shape and color.” Patent Nr.5015312. 27 Dec. 1988. 28 Aug. 2008 <http://www.google.com/patents?id=2qsjAAAAEBAJ&dq=5015312>.

[7] Gormet, Tim . “Viewpoint: History of Additive Fabrication (Part 1) .” Wohlers Associates. 28 Aug. 2008 <http://wohlersassociates.com/MarApr08TCT.htm>.

[8] A detailed overview on this additive fabrication technique that informs about material properties, build sizes and manufacturers of Rapid Prototyping Technologies can be found in the appendix.

[9] A detailed overview on this additive fabrication technique that informs about material properties, build sizes and manufacturers of Rapid Prototyping Technologies can be found in the appendix.

[10] A detailed overview on this additive fabrication technique that informs about material properties, build sizes and manufacturers of Rapid Prototyping Technologies can be found in the appendix.

[11] Deckard, Carl. “Multiple material systems for selective beam sintering.” Patent number: 4944817. 5 Sep. 1989. 28 Aug. 2008 <http://www.google.com/patents?id=hsoeAAAAEBAJ>.

[12] Sachs, Emanuel M, John S. Haggerty, Michael J. Cima, and Paul A. Williams. “Three-dimensional printing techniques.” Patent number: 5340656. 9 Apr. 1993. 28 Aug. 2008 <http://www.google.com/patents?id=xOonAAAAEBAJ&dq=5340656>.

[13] “Rapid Tooling — Fraunhofer-Allianz Rapid Prototyping.” Fraunhofer-Allianz Rapid Prototyping . 28 Aug. 2008 <http://www.rapidprototyping.fraunhofer.de/ver2/en/newspr/rapid_tooling.php>.