Abstract
Shape Deposition Manufacturing (SDM) is a layered manufacturing process that combines the benefits of Solid Freeform Fabrication (SFF), thermal spray and other manufacturing processing operations for fabricating multi-material objects of arbitrary three-dimensional geometric complexity with controlled microstructures and for embedding electronic components and sensors in conformal shape structures. SDM involves molten metal droplet deposition, remelting and solidification as well as the use of sacrificial support materials. Therefore a thorough understanding of the thermal issues is required to select SDM process parameters and to enable the integration with SDM computer-based design systems.
Important thermal issues in the production of high-quality SDM objects are the creation of inter-layer metallurgical bonding through substrate remelting, the control of cooling rates of both the substrate and the deposition material, and the minimization of residual thermal stress build-up which may induce warping and debonding between deposited layers. This paper presents brief descriptions of the thermal modeling approach, the numerical prediction of the cooling rates and substrate remelting depths of steel deposited on steel and on copper, and the analytical and experimental methods used to verify temperature histories. Through the integration of these different tools, accurate and useful information is available to assist in the selection of operating parameters during the manufacture of microcast artifacts.