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Ford Motor Company, Power Train Operations is
located in Dearborn, Michigan. This organization is responsible
for the design, engineering and manufacturing of Ford's
worldwide engines and transmissions for Ford and Ford's
worldwide subsidiaries. They required a new power train assembly
for a newly designed automotive model. Although the base engine
design was complete, the top cast support bracket, a component
that holds the engine in proper position in the engine
compartment, was still under development. Only four weeks
remained before the scheduled delivery of six complete engine
assemblies to Europe. Without this bracket, the development
program and testing cycles could not proceed on time.
Ford's challenge now centered on how to
produce a prototype aluminum support bracket, allow adequate
time to cast and machine the parts and test the components
within the 4-week time frame. At this point, Ford only had the
CAD drawings to assess the design, and there was not enough time
to create tools to produce the casting patterns. Moreover, there
was reluctance to create expensive tooling at this stage. If
Ford was forced to rethink material choices, separate tooling
would be required to handle the different shrinkage rates of the
alternate materials.
Because of the speed of the Z Corp 3D
Printer, Ford was able to create 3D conceptual models as well as
actual casting patterns. The first model produced was used as a
design and fit aid. It was made to scale and was placed inside
the actual engine to determine if the design was correct. After
making one minor change to the CAD file, the design was
accepted, and six Z Corp patterns were produced for casting.
These patterns were printed to reflect shrinkage that would
occur after the metal was poured for casting. The six patterns
made for the six engine assemblies were then sent to an
investment casting foundry for production.
The foundry that Ford used is experienced
using RP patterns for investment casting. The cast aluminum
parts were produced within three weeks and delivered for
machining. This was a considerable improvement in speed; the
foundry reported that production of parts like these from other
RP methods traditionally takes up to twice as long because of a
combination of build time, post-processing and foundry
preparation. Because of the wax coating available on the Z Corp.
models, a simple method of attaching gates and runners was
quickly developed at the foundry and there were no problems with
expansion or shell cracking. In addition, burn-out resulted in
acceptable levels of residual ash, which was easily removed from
the molds.
The six parts that were investment cast had a
100% success rate with no pattern or shell problems. The parts
showed no sign of surface deformation and a uniform tolerance
level was measured. The parts were delivered in time to allow
for machining and assembly. The completed prototype assemblies
were shipped to Europe on time and at Ford's high quality
standards.
RPD has given Ford the potential to reduce
many intangible operating expenses and improve their operations
through: (1) early detection of design flaws; (2) improved
communication of design intent to suppliers, engineers and
designers; (3) reduction of Powertrain's overall time to market.
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