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Rapid Tooling & Metal Parts by Additive Fabrication (C) Copyright Castle Island Co., All Rights Reserved.
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 Tooling & Metal Part Technology Comparison Tables...
Sand CastingsThe sand casting process starts by tightly compacting fine, moist foundry sand in a box-like frame around a pattern which is typically made of wood. The pattern is removed from the sand to leave a cavity into which the molten metal is poured. Once the metal cools and hardens, it's removed from the sand, which is then recycled. As with investment casting, it may be necessary to remove extra material and perform finish machining and clean-up.
Indirect or Secondary Processes that Utilize RP-generated PatternsLaminated object manufacturing (LOM) has been a popular way to produce patterns for sand castings. The large size of parts that can be produced, and their similarity to wood patterns historically used in the process have been important factors. It may be necessary to seal the LOM-generated pattern against moisture to guarantee dimensional stability.Parts made using other methods of RP, such as stereolithography are also used in the process, and may have some advantages compared to laminated object manufacturing in terms of tolerances, finish and dimensional stability. However, sand casting is often used for very large parts and LOM has an advantage there. Direct Fabrication of Sand Casting PatternsIt's possible to skip the step of building a pattern for a sand casting mold altogether. This may be advantageous in the early stages of a project before final dimensions and other parameters may have been determined, or if very few castings are required, making the cost of producing a pattern prohibitive.Selective laser sintering (SLS) systems are available that fuse polymer coated sand layer by layer to form sand casting molds. EOS GmbH has dubbed this method DirectCroningTM. One limitation is the size of molds that can be produced. A solution for much larger parts is offered by ProMetal RCT GmbH (Rapid Casting Technology) of Germany. Their machine use a wide area inkjet to bond layers of sand into sand casting and core patterns, and has a build volume of 59 x 29 x 29 inches. The method is reminiscent of the 3 Dimensional Printing process developed by MIT. A build chamber full of sand weighs several tons. Clinkenbeard & Associates offers a process that avoids the use of additive fabrication altogether. Fairly robust blocks of sand are formed using a polymer binder. The blocks are subsequently machined using diamond tools and standard CNC techniques to fabricate a hollow mold in which metal is directly cast. Die-CastingsThe processes that are used to make metal die casting molds are similar those used to fabricate metal injection molds. Please see that section. However, low-cost prototype plaster die casting molds have also been fabricated using RP generated patterns. This is accomplished by casting plaster material against an RP-generated pattern in a process similar to making an RTV rubber mold. |
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Rapid Tooling & Metal Part Technology Comparison Tables.
Rapid Manufacturing; What RP will be when it grows up.
RP System Manufacturers.
Bridge Tooling and Related Listings.
Service Bureaus.
RP Technology, Brief Tutorial.
RP's Frequently Asked Questions.
