1.9 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.
1.9.1 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,
1.9.2 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.