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1. From sample or drawing,
we use CAD to ease the tooling or pattern design. |
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2. Example of tooling for
investment casting process: It is machined from Aluminum alloy
with cavity shape as a negative of the part. |
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3. Example of pattern for stack shell mold process: It is
machined from cast iron with raised shape as (positive way)
same as the part.
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4. Special wax is injected into the cavity to make a pattern.
The pattern is cooled in the tooling to stable form. The pattern
is removed from the tooling.
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5. The pattern is touched up ,such as removing unnecessary
flash, or mounting some wax pieces to form more complex part.
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6. All finished pattern must be inspected according to requirement,
guarantee that no any defective parts happen during following
process.
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7. The pattern (one or more) are attached to a central sprue.
The sprue, gates and runners form the channels where metal
will flow which is often called a "tree".
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8. 8-1 to 8-3 The pattern tree is dipped
into a ceramic slurry and then into an air fluidized bed of
ceramic sand. This is repeated to form a thin self supporting
ceramic "shell". |
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9. After controlled drying , the ceramic shell is heated
in a steam autoclave to melt out the pattern wax.
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10. The shell mold is then fired to strengthen it and burn
out any remaining pattern material. Also the shell mold is
preheated to protect the mold shock during pouring because
of too much gradient temperature.
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11. In the meantime, the molten metal is prepared by induction
furnace. The spectrometer is used to confirm that the chemical
composition is conformed to standard. The result will be recorded
for future reference(in case necessary).
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12. 12-1 to 12-3 The molten metal is poured
into the preheated mold, producing a metal duplicate of the
original pattern. |
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13. After the metal has solidified and cooled, the ceramic
mold material is mechanically removed, leaving the tree of
cast metal parts.
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14. 14-1 to 14- 4 The individual castings
are cut from the tree. Feed gate stubs are ground off, and the
castings are cleaned by shot blasting or sand blasting. |
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15. Quality Assurance:
15-1 Dimensional inspection
15-2 Hardness testing
15-3 Microscope for identify microstructure of the metal. |
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