Processing, Thermal and Mechanical Issues in Shape Deposition Manufacturing

Abstract

An overview of Shape Deposition Manufacturing (SDM) is presented, detailing
\nmanufacturing, thermal and mechanical issues of concern in making it a commercially viable
\nmethod for creating arbitrarily shaped three-dimensional metal parts. SDM is a layered
\nmanufacturing process which combines the benefits of solid freeform fabrication and other
\nprocessing operations, such as multi-axis CNC machining. This manufacturing process makes
\npossible the fabrication of multi-material layers, structures of arbitrary geometric complexity,
\nartifacts with controlled microstructures, and the embedding of electronic components and sensors
\nin conformal shape structures. Important issues toward the production of high quality objects are
\nthe creation of inter-layer metallurgical bonding through substrate remelting, the control of cooling
\nrates of both the substrate and the deposition material, and the minimization of residual thermal
\nstress effects. Brief descriptions of thermal and mechanical modeling aspects of the process are
\ngiven. Because SDM involves molten metal deposition, an understanding of thermal aspects of the
\nprocess is crucial. Current thermal modeling of the process is centered on the issue of localized
\nremelting of previously deposited material by newly deposited molten droplets. Residual stress
\nbuild-up is inherent to any manufacturing process based on successive deposition of molten
\nmaterial. Current mechanics modeling is centered on the issues of residual stress build-up and
\nresidual stress-driven debonding between deposited layers.