Production of overhang, undercut, and cavity structures using direct metal depostion

This invention relates generally to laser-based additive manufacturing and, in particular, to direct-metal deposition, or DMD. More specifically, this invention relates to the production of overhang, undercut, and cavity structures using DMD processes. Overhang and undercut features, as well as cavities, channels, pipes and three-dimensional voids and other structures are fabricated using a laser-aided direct-metal deposition (DMD) processes. In the preferred embodiment, this is accomplished through the selective deposition of a lower melting point sacrificial material. Following the integrated deposition of both sacrificial and non-sacrificial materials using DMD, the part is soaked in a furnace at a temperature sufficiently high to melt out the sacrificial material. As preferred options, the heating is performed in an inert gas environment to minimize oxidation, with a gas spray also being used to blow out remaining deposits. Using this technique, articles having integral sensors and cooling channels may be used as part of an automated system for controlling the temperature, stress and strain during the shaping or forming of a product using the resultant smart die or mold. Such a system would preferably include means of controlling the inlet flow of coolant and means for controlling or terminating the forming or injection process. The control is preferably mediated through a computer which analyzes and evaluates the inputs from the sensors and transmits the resulting information to a flow controller and to a process controller or logic gate, so that appropriate actions are carried out on a continuous basis.