FDM works on an "additive" principle by extruding material in layers. A plastic filament is unwound from a coil and pulled through to an extrusion nozzle which turns the flow on and off. The nozzle is heated to melt the material and is moved both horizontally and vertically by a mechanism which is controlled directly by a Computer Aided Design software package. In a similar manner to Stereolithography, the model is built up from layers as the plastic hardens immediately after extrusion from the nozzle.

The Dimension SST Printer uses Acrylonitrile Butadiene Styrene (ABS) Plastic to print solid objects at extremely high resolution directly from 3D CAD files in *.stl format. The ABS models are built up in thin layers, 0.01 in. to 0.013 in. thick. The resulting models are white, sturdy and can be sanded, drilled etc. with typical hand- and power tools. A water-soluble material is used for making temporary supports during manufacturing, which can be dissolved away with a cleaning solution. No further post-processing is required for the models.

Several materials are available with different trade-offs between strength and temperature. As well as ABS plastic, the FDM technology can also be used with polycarbonates, polyphenylsulfones and waxes. Developments in the technology have seen the introduction of magnetic levitation to move the extruder head in place of conventional wires and electric motors.

For more information regarding Fused Deposition Modeling and other Rapid Prototyping technologies please see the Stratasys website at www.stratasys.com.

The ZCorp 450 3D printer in DS334 uses Three-Dimensional Printing technology (3DP™) originally developed at the Massachusetts Institute of Technology (MIT) in 1993. 3DP technology creates 3D physical prototypes by solidifying layers of deposited powder using a liquid binder. It is an extremely versatile and rapid process which accommodates geometry of varying complexity in hundreds of different applications, and supports many types of materials.

The ZCorp 450 printer uses standard inkjet printing technology to create parts layer-by-layer by depositing a liquid binder onto thin layers of powder.  Once the layer of powder is spread, the inkjet print heads print the cross-sectional area for the first, or bottom, slice of the part onto the smooth layer of powder, binding the powder together. The build platform is then lowered 0.1016mm (0.004”) and a new layer of powder is spread on top. The print heads apply the data for the next cross section onto the new layer, which binds itself to the previous layer. The printer repeats this process for all of the layers of the part.

After the materials have had time to set, loose powder can be blown off the part for later reuse. The ZCorp 450 can also print in color, using 4 colored binders (cyan, magenta, yellow, and clear) to print colors onto the shell of the part. 

For more information on the 3DP technology, see the Z Corporation 3D Printing Technology White Paper at www.zcorp.com/en/Products/3D-Printers/ZPrinter-450/spage.aspx.