66.9 BALLISTIC PARTICLE MANUFACTURING (BPM)

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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.

66.9.1 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,

66.9.2 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.