Robot Mechanisms and Mechanical Devices Illustrated - Profe Saul

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Introduction
laser fusing of ceramic powders to fabricate parts as an alternative to the
use of metal powders. A system that would regulate and mix metal powder
to modify the properties of the prototype is also being investigated.
Optomec Design Company, Albuquerque, New Mexico, has
announced that direct fusing of metal powder by laser in its LENS
process is being performed commercially. Protypes made by this method
have proven to be durable and they have shown close dimensional tolerances.
Research and Development in RP
Many different RP techniques are still in the experimental stage and have
not yet achieved commercial status. At the same time, practical commercial
processes have been improved. Information about this research has
been announced by the laboratories doing the work, and some of the
research is described in patents. This discussion is limited to two techniques,
SDM and Mold SDM, that have shown commercial promise.
Shape Deposition Manufacturing (SDM)
The Shape Deposition Manufacturing (SDM) process, developed at the
SDM Laboratory of Carnegie Mellon University, Pittsburgh,
Pennsylvania, produces functional metal prototypes directly from CAD
data. This process, diagrammed in Figure 10, forms successive layers of
metal on a platform without masking, and is also called solid free- form
(SFF) fabrication. It uses hard metals to form more rugged prototypes
that are then accurately machined under computer control during the
process.
The first steps in manufacturing a part by SDM are to reorganize or
destructure the CAD data into slices or layers of optimum thickness that
will maintain the correct 3D contours of the outer surfaces of the part and
then decide on the sequence for depositing the primary and supporting
materials to build the object.
The primary metal for the first layer is deposited by a process called
microcasting at the deposition station, Figure 10(a). The work is then
moved to a machining station (b), where a computer-controlled milling
machine or grinder removes deposited metal to shape the first layer of
the part. Next, the work is moved to a stress-relief station (c), where it is
shot- peened to relieve stresses that have built up in the layer. The work
is then transferred back to the deposition station (a) for simultaneous
deposition of primary metal for the next layer and sacrificial support