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extrusion tooling for
the development and commercialization of the rapid solidification process
within the field of tooling (RSP tooling), which is a recent revolution in
the moldmaking industry. The first production of
extrusion tooling machine is scheduled
for delivery this year. This machine will be able to produce a 6 x 6 x 4
inch tool with finished cavities in two hours. Such a production rate is
revolutionary, and will likely change the tooling industry dramatically.
Related words are design of rigid pvc profile, plastic bimetallic in pvc
catheter for western molding head.
The
extrusion tooling process is a method of producing production level
tooling in prototype timing. While generically a spray forming method, it
differs from other approaches. Molten metal (e.g., molten tool steel) is
sprayed onto a ceramic pattern, replicating the pattern's contours, surface
texture and details, until the desired thickness is reached (see
extrusion tooling). The deposit is cooled to room temperature, separated
from the pattern, and its exterior is machined to fit into a standard mold
base (see Figure 2). The latter is accomplished using conventional practices
or wire EDM, depending on the hardness of the deposit.
extrusion tooling alloy
The desired tooling alloy is loaded into a crucible and heated to about
100'C above its melting point. The molten metal is injected into a nozzle,
where it is exposed to a flowing gas stream. The high-velocity gas jet
breaks the molten metal into tiny droplets, about 50 microns diameter, which
are carried by the gas stream and deposited onto the pattern surface (see
extrusion tooling). Transit time from the nozzle to the pattern is about
one millisecond. Since the tooling alloy stock material is melted during the
process, any form - cast metal, forged metal, powder or scrap - is suitable,
provided the chemistry is within alloy specification limits.
The extrusion tooling machine is a self-contained unit. The equipment
is configured so that the nozzle remains stationary while the pattern is
manipulated in the spray. The metal is maintained in a liquid state while it
is inside the nozzle, but upon exiting, gas at room temperature is drawn
into the jet, cooling the droplets and causing them to solidify rapidly. The
spray of droplets results in a huge increase - by 10 orders of magnitude -
in the surface area of the metal. The metal's latent heat (enthalpy of
solidification) is extracted rapidly from the droplets as they travel from
the nozzle to the ceramic pattern, resulting in about 70 percent of the
sprayed material having solidified by the time it reaches the pattern. The
remaining liquid fraction is enough to "weld" the metal together on the
pattern surface.
extrusion tooling rate
The high deposition rate, about 500 lbs./hr., results in a coherent build-up
(rather than layering) on the pattern. Rapid solidification eliminates
segregation of alloying additions in tool steels and produces a
supersaturated solid solution, which allows the alloy to be artificially
aged to obtain a more uniform carbide distribution and a unique combination
of properties without the risk of tool distortion. Related words are design
of rigid pvc profile, plastic bimetallic in pvc catheter for western molding
head. Tests have shown that the properties of H13 tool steel that has been
artificially aged compare well with the commercial forged/heat treated
material. In-service studies conducted by Global Metal Technologies, Inc. (GMTI),
Brigham Young University and Case Western Reserve University (CWRU) have
indicated that
extrusion tooling are at least as good as standard machined tools. In
the case of H13, GMTI found that the life of extrusion tooling
expectancy of a tool during aluminum die casting increased by 20 percent and
CWRU found a reduction in soldering by weight compared to other steel
inserts. Related words are design of rigid pvc profile, plastic bimetallic
in pvc catheter for western molding head.
At this point in its development,
extrusion tooling is limited to creating tools with a maximum of 4:1
aspect ratio. Even with that limitation, however, it is estimated that the
process could be used to create about 80 percent of the tools used in the
extrusion tooling industry
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