| |
 |
Step 1: The process begins with production of a one piece pattern. This
pattern is usually made by injecting wax into an aluminum die. These dies
may range from a simple hand operated single cavity tool to a fully automated
multi cavity tool, depending on quantities and complexity. |
|
 |
 |
|
 |
| |
 |
Step 2: Patterns are fastened by the gates to one or more runners. The
runners are attached to the pouring cup. Both are usually made of wax. Patterns,
runners and pouring cup comprise the sprue or tree, which is needed to produce
the ceramic mold. |
|
|
|
|
|
| |
 |
Step 3: The investment shell technique involves dipping the entire cluster
into a ceramic slurry giving the cluster its initial face coat.
After drying, the cluster is coated again and again using progressively
coarser grades of ceramic material, until a self-supporting shell has
been formed. The shell may run between 3/16 to 5/8 inches thick.
|
|
|
|
|
|
| |
 |
Step 4: The coated cluster is placed in a high temperature furnace or
steam autoclave where the pattern melts and runs out through the gates,
runners and pouring cup. This leaves the foundry with a ceramic shell containing
cavities of the casting shape desired with passages leading to them.
|
|
|
|
|
|
| |
 |
Step 5: The molds must be fired to burn out the last traces of pattern
material and to attain a certain degree of permeability before they can
be filled with metal. In the case of solid molds, this heating has to proceed
slowly, in a controlled cycle which stretches over 12 to 18 hours to avoid
cracking.
|
|
|
|
|
|
| |
 |
Step 6: Molten Metal is poured into the fired shell at temperatures exceeding
1000 degrees Fahrenheit which varies depending on the type of alloy.
O'Fallon also uses its superior countergravity
casting technology.
|
|
|
|
|
|
| |
 |
Step 7: After the poured metal has cooled, the mold material is removed
from the casting cluster using high pressure water. This image illustrates
a complete cluster just after the mold or outside shell has been removed. |
|
|
|
|
|
| |
 |
Step 8: The individual castings are removed from the cluster and any remaining
protrusions left by gates or runners are removed by grinders. Generally
the castings are sand blasted for a smoother finish. The castings are then
ready for secondary operations. |
|
|
|
|
|
| |
 |
Step 9: After minor finishing operations, the metal castings--identical
to the original wax patterns--are ready for shipment to the customer.
|
|
