| Below are brief descriptions of the capabilities of The
Eagle Group. Hopefully these will help you choose the casting
method that’s right for your project.
Shell mold process
Offered by Eagle Alloy, this process is the industry standard
for medium to high volume, commercial grade casting projects.
For a better look at how the process works, we offer a video
animation for your convenience.
Thermally bonded sand is applied to the surface of a pre-heated
pattern usually made of cast iron or steel. The “baked”
mold is lifted from the pattern in halves. The halves are
glued together, assisted by precise locating features to avoid
shifting. The Shell process offers tolerances of +/-.030”
on dimensions 6” or less and a surface finish around
200 – 250 RMS. Click here for a complete description
of available tolerances, radii, fillets and other design considerations.
Advantages: good casting detail, excellent
repeatability, very productive, less machine stock required
than in greensand or no-bake processes, competitive pound-prices,
very short production lead times.
Disadvantages: tooling prices higher than
some other process
Lost-wax investment process
Eagle Precision Cast Parts uses this process exclusively.
Wax is injected into an aluminum die to create a wax “pattern”.
These wax patterns are then assembled onto a “tree”
which is repeatedly dipped in a ceramic slurry that, after
drying, hardens into a mold. The wax is melted out, the mold
is preheated and the metal is poured in. The resulting casting
has an excellent surface finish of around 125 RMS, crisp lettering
and minimal machine stock. This process is perfect for highly
visible or highly machined parts. Tolerances can be held to
+/-.005” in most cases.
Advantages: excellent overall appearance,
machining reduced or eliminated, can cast very thin walls,
good for prototypes, economical tooling costs.
Disadvantages: higher pound-prices.
Permanent Mold (gravity pour)
The term “permanent mold” describes a mold that
can be used repeatedly, in contrast to sand-molds that must
be destroyed to remove the casting. This is only one of the
casting methods offered by Eagle Aluminum Cast Products. Permanent
molding is desired by those requiring an aluminum casting
with good density and superior mechanical properties. Castings
made with this method are much more dimensionally accurate
and repeatable than those made using sand methods. This reduces
or eliminates much of the machining that may be required.
Advantages: very repeatable, sound density,
can utilize cores in the casting design, short lead times,
excellent appearance, tight tolerances, perfect for high volume.
Disadvantages: tooling prices higher than
those used in sand processes.
Greensand (aluminum)
Along with permanent molding, Eagle Aluminum Cast Products
offers castings made with the greensand molding method. Greensand
molding is the most diversified molding method in use today.
Loose sand is mixed with a bonding agent and moisture then
compacted onto a pattern. After both halves of the mold are
made they are positioned together and filled with molten aluminum.
Eagle Aluminum’s expertise makes us one of the few capable
of casting very large castings with very thin sections.
Advantages: low pattern costs, speed to
market, not quantity-sensitive, can utilize cores in the casting
design.
Disadvantages: not suitable for smaller
parts, “grainier” surface finish than perm mold.
CNC Machining
Eagle CNC Technologies utilizes the latest in machining technologies
and has experience machining all types of casting and wrought
materials. Our services are mainly utilized by, but are not
restricted to, the Eagle Group. Our commitment to maintaining
available capacity means our facility list is constantly expanding
with the latest and greatest machines available. Contact us
to discuss your next machining project.
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