Fused deposition modeling

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Fused deposition modeling, which is often referred to by its initials FDM, is a type of rapid prototyping or rapid manufacturing (RP) technology commonly used within engineering design. The technology was developed by S. Scott Crump in the late 1980s and was commercialized in 1990. The FDM technology is marketed exclusively by Stratasys Inc.

Like most other RP processes (such as 3D Printing and stereolithography) FDM works on an "additive" principle by laying down material in layers. A plastic filament or metal wire is unwound from a coil and supplies material to an extrusion nozzle which can turn on and off the flow. The nozzle is heated to melt the material and can be moved in both horizontal and vertical directions by a numerically controlled mechanism, directly controlled 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.

Several materials are available with different trade-offs between strength and temperature. As well as ABS polymer, the FDM technology can also be used with polycarbonates, polyphenylsulfones and waxes. A "water-soluble" material can be used for making temporary supports while manufacturing is in progress. Marketed under the name WaterWorks™ by Stratasys this soluble support material is actually dissolved in a heated sodium hydroxide solution with the assistance of ultrasonic agitation. Most current modelers use stepper or servo motors to move the extrusion head.

As of 2002 it has been the best-selling Rapid Prototyping technology, while simpler, cut-down versions of the system have been introduced in recent years, released under the Prodigy and Dimension trademarks.

The RepRap Project intends to develop an open source FDM machine that is capable of manufacturing most of its own parts, with only cheap commodity components such as electric motors needed to build a fully functional copy. It will also be capable of depositing Wood's metal to form conductive circuit paths within the objects it manufactures.

[edit] External links

• RepRap, open-source self-replicating FDM machine development.
• Castle Island Castle Island's worldwide guide to rapid prototyping
• Stratasys