Laminated object manufacturing (LOM) has often been the method of choice for large sand casting patterns, but has become less-commonly available in recent years. ProMetal RCT GmbH (Germany) provides a process similar to three dimensional printing (3DP) which avoids the use of a pattern altogether. The process is not available from service bureaus. Smaller, more intricate patterns can be made by laser sintering (LS), stereolithography or jetted-photopolymer methods.
Investment Casting
Special stereolithography build styles, such as QuickCast,TM can be used to create a pattern which burns out of an investment cleanly and without fracture. Direct shell production casting (DSPC) based on three dimensional printing (3DP) technology from Soligen is used to make large investments with no patterns at all. The company runs a vertically integrated molding house called Parts Now, but in recent years has de-emphasized its involvement with additive fabrication to a considerable extent.
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Investment casting shell fabricated by direct shell production casting (DSPC). The openings are for gates and risers.
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Investment casting shell showing internal features and casting. Water jackets and part cores are integral parts of the mold.
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Large, complex investment casting fabricated by direct shell production casting (DSPC).
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SLS-generated polystyrene casting patterns and castings.
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(All DSPC photos courtesy, Soligen, Inc.)
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(Courtesy, Accelerated Technologies,Inc.)
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Selective laser sintering (SLS) parts made from polystyrene and other plastics can be used in the investment casting process, as well. Fused deposition modeling (FDM) is often used for smaller parts, and paper-based laminated object manufacturing (LOM) patterns can be burned out of an investment to fabricate medium sized to larger parts. In some cases LOM patterns may leave a residue that might have to be cleaned out manually. However, as mentioned above, LOM has become less available in recent years.
Solidscape's ModelMaker™ (MM) inkjet-based technology is a very high resolution process and offers the greatest precision of any additive technologies, making it especially advantageous for small intricate items such as jewelry. Perfactory™ technology from Envisiontec GmbH is also a good choice for such applications, and 3D Systems InVision™ inkjet-based photopolymer machines offer high-resolution, as well.
A process which has enjoyed considerable success for investment casting in the past is MultiJet Modeling™ (MJM) from 3D Systems. The company's ThermoJet™ machines based on this technology using wax hot melt materials are still in use in many service bureaus, although they are now considered legacy systems. The combination of materials and part size fits the needs of this market very well.
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QuickCast (TM) stereolithography investment casting pattern broken open to show internal structure.
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MultiJet Modeling (MJM) investment casting pattern for a ring, with support structure.
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MultiJet Modeling (MJM) investment casting pattern and casting.
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ModelMaker inkjet-based investment casting pattern for a ring.
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(Courtesy, Cadem A.S., Turkey)
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(Courtesy, Cadem A.S., Turkey)
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(Courtesy, Cadem A.S., Turkey)
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(Courtesy, Bathsheba Grossman Protoshape, Inc. Ring designed by Charles Bahringer, Out of Solitude Custom Jewelry)
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Die Casting 
Selective laser sintering (SLS) can directly fabricate metal dies which can produce hundreds of parts. Laser powder forming processes have also been used for this application which has very stringent material requirements. Any other additive method can also be used to make a die through indirect processes.
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Die casting mold fabricated by Laser Engineered Net Shaping (TM).
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(Courtesy, Optomec Design Co.)
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