Examples Of Parts Built With SDM
Embedded Electronics
An example of a heterogeneous product design is an embedded electronic device fabricated by building up a nonconductive housing package and simultaneously embedding and interconnecting electronic components within the housing. With this approach it is feasible to fabricate compact, rugged, customized computer modules in small lot sizes. This capability is particularly well suited for military and industrial applications to manufacture mission-specific, conformal shaped 'smart' devices such as wearable computers. These computers might store maps, equipment descriptions, help to log data, or provide communication links. For one example, the 'Frogman' (completed part shown in left side of figure above, and CAD model in the middle) is a water-proof computer which can store maps for navigational aids, or detailed assembly drawings for service, maintenance, or field operations.. The graphical information, which is stored on PCMCIA cards, is displayed on a heads-up display. The device is built up in layers of polyurethane (PU) and sacrificial wax. The PU is deposited as a 2-part thermoset. The important points are that custom tooling was not required to manufacture the Frogman and that embedding facilitates waterproofing. [For more information see Weiss, L. and Prinz, F., "Novel Applications and Implementations of Shape Deposition Manufacturing," Naval Research Reviews, Office of Naval Research, Three/1998, Vol. L , or Weiss, L.E., Neplotnik, G., Prinz, F.B., Schultz, L., Padmanabhan, P, Krishnan, R., and Merz, R.., "Shape Deposition Mnaufacturing of Wearble Computers," 1996 Solid Freeform Fabrication Symposium, The University of Texas At Austin, Auust, 1996.]
Advanced Tooling
Another inteteresting heterogeneous product design would be mutli-material, steel/cooper injection mold tool with internal conformal cooling channels. The channels would be formed using sacrificial material. The interior of the tool would be made of copper, for fast and uniform heating/cooling, while the outside shell would be made of steel. To demonstrate the feasibility of using SDM to manufacture such structures the hemispherical shaped structure shown in thef igure above was built using microcasting. The structure is compposed of 308 stainless steel outer shell, a permanent copper interior, and conformable channels as depicted in the CAD drawing. [For more information see L.E. Weiss, R. Merz, F.B. Prinz, G. Neplotnik, P. Padmanabhan, L. Schultz, K. Ramaswami " Shape Deposition Manufacturing of Heterogeneous Structures," SME Journal of Manufacturing Systems, Vo. 16, No. 4, (1997) pp. 239-248]
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Rotor |
These are examples of a silcone nitride components built with the Mold SDM process. The part on the left is an inlet nozzle design that is intended for use in a minature turbine engine. It experiences the highest static temperatures in the engine. Estimates indicate that a ceramic inlet nozzle could increase engine performance by 7% compared with a metal nozzle. The first design of the inlet nozzle was tested on a jet engine test rig and survived under the flow of 1250°C, high pressure gas expected in the turbine engine application. [For more information see S. Kang, A. Cooper, J., Stampfl, F. Prinz, J. Lombardi and L. Weiss, "Improving Quality of Ceramic Parts with Mold SDM," 1999 Solid Freeform Fabrication Symposium, The University of Texas At Austin, August, 1999]. The part on the right is a rotor for the engine.
Structural Ceramics Built with Extrusion SDM
An example of a 'green' ceramic part built on the integrated SDM shaping/deposition machine is displayed in the figure above. The part material is silicon nitride, and the support material is ACR 200 which is a proprietary non-ionic, water-soluble, machinable thermoplastic. While this particular shape could have been cut directly from a block of 'green' ceramic stock, such conventional machining would require reorienting, efixturing, and registering of the part after one side has been cut, since this shape has under-cut features. Another advantage of SDM over conventional machining is that first depositing shapes in near-net, before machining, reduces the waste of costly materials.
Nozzle
