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-it is faster to spray adhesive than fuse/cut with laser

-final materials only limited by casting

•disadvantages,

-rough surface finish: details down to 0.175mm; tolerance +/- 0.05mm

-unbound powder can clog in hidden cavities

-the printing jet tends to clog.

-not commercially available yet

-small work envelope

•work volume is 8” by 12” by 8”

•resolution of print head 0.007”

•cost for alpha machine $200,000US

•Expected machine in 1994 is,

-$250,000US

-20” by 20” by 20”

-0.002” resolution

-5 min/layer

-9 to 20 hours for build

65.9 BALLISTIC PARTICLE MANUFACTURING (BPM)

•Developed by BPM technology

•Sprays material (wax) in 0.002” drops at rates of 12,500 drops per sec to build up slices

•The elevator drops as slices are formed

•Variable slice thickness is set by changing the flow rate

•Part material supports are made from water soluble wax (polyethelene glycol) and are removed after completion by placing the model in water

•The BPM personal modeler is $35,000

•Incremental fabrication is a ballistic particle method developed by Incre Inc. but molten metal is used instead.

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65.9.1 Sanders Prototype

•This methods uses two thermoplastic materials the positive having a higher melting temperature. The materials are distributed by a head that will melt and deposit either material (much like an ink jet printer head doing multiple colors). A raster scan is used to build up layers until the final composite part is done. The lower temperature material is melted away to leave the inner part.

•This method is very good for small parts, and produces parts in engineering materials.

•There are two commercially available units,

65.9.2 Design Controlled Automated Fabrication (DESCAF)

•Invented in 1986 by Efrem Fudim

•Marketed by Light Sculpting Inc.

•Uses photomasks of layers to develop sections.

•Exposes the parts to UV light, and develops the photomask

•Requires about 40 sec/layer

•Expected specs.