(Direct Shell Production Casting)
DSPC (Direct Shell Production
Casting) produces the actual ceramic molds
for metal castings directly from 3-D CAD
designs. No tooling or patterns are required.
DSPC uses Three Dimensional Printing technology
to produce the ceramic casting molds using
a layer-by-layer process.
The CAD file of the designed
part is transferred via modem or magnetic
tape to the Shell Design Unit (SDU) of the
DSPC system. The SDU operator then designs
the ceramic mold for casting the metal part
by adding the gating system to the part
geometry and converting the updated file
into a cavity file in CAD space. This is
a one time process after which many identical
ceramic mold could be generated. The cavity
file for the ceramic mold is then used to
automatically generate the ceramic casting
The ceramic mold is created
in layers. The fabrication process involves
three steps per layer. First, the ceramic
shell model is "sliced" to yield a cross-section
of the ceramic mold. Second, a layer of
fine powder is spread by a roller mechanism.
Third, a multi-jet printhead moves across
the section, depositing binder in regions
corresponding to the cross-section of the
The binder penetrates the
pores between the powder particles and adheres
them together to form a rigid structure.
Once a given layer is completed, the ceramic
shell model is sectioned again, at a slightly
higher position, and the process is repeated
until all layers of the mold are concretized.
The DSPC mold is then cleaned of excess
powder, fired and poured with molten metal.
A DSPC mold may contain
an integral ceramic core, producing a hollow
metal part. Virtually any molten metal can
be cast in DSPC molds. Automotive parts
have already been manufactured in aluminum,
magnesium, ductile iron, and stainless steel.
The DSPC machine is like
a three dimensional printer that uses the
designerís Computer Aided Design to create
the actual ceramic casting molds. Consequently,
it expedites the design and the functional
testing of new automotive components such
as engines, transmissions and turbochargers.
First article parts, made directly from
the customerís CAD, are delivered in days.
Importantly, any design change is easily
incorporated in CAD space, which provides
the ultimate configuration control and assures
that all design changes are properly documented.
With DSPC, production tooling
(dies, patterns and core boxes) are cast
as net shape tools from the CAD file of
the approved part. This tooling is now created
only once, guaranteeing a smooth and cost
effective transition from the first article
part to production. The need for temporary
(prototyping) tooling is eliminated, and
so are the huge monetary outlays associated
with prototype tooling that previously had
to be considered. With DSPC, an indefinite
number of design iterations, including testing
the design with different alloys, can be
created without the costly and time consuming
need to produce tooling with each step.