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2. When using wax patterns assembled on wax runners, the tree assembly should go though an autoclave
process for 10 minutes before being put in the firing oven. The autoclave should be 380
o
F (193
o
C) and 130 psi (9
bars). The pattern should then be put in the burnout oven. Note: this process has been omitted by some users
to their satisfaction.
Patterns infiltrated with resin should skip the autoclave process and go directly to the burnout oven.
3. Z Corp. patterns should be burned out at 1750-1800
o
F (954-982
o
C) in an oxygen rich environment. Burnout
time will depend on the part volume and air circulation. If the part is an inch thick or less, it should burn out
completely in two hours. For larger parts, a longer burnout time should be expected. The patterns will burn out
completely if they are left in the oven for a sufficient amount of time.
Low-temperature furnaces with air treatment devices using ionized air have also been utilized successfully to
burn out Z Corp. patterns. Refer to the furnace manufacturer for guidelines for this process.
4. After burn-out, allow the shell to return to room temperature. In some cases, a small amount of residual ash
may remain (less than 1%). This can typically be washed or blown out of the mold. Wash the shell out with water.
Allow the shell to dry and thoroughly pre-heat shell before pouring metal to entirely eliminate any water vapor that
may remain.
Results
2% shrinkage should be expected when going from the Z Corp. pattern to a cast part. The surface finish will
depend on the surface of the original pattern, but can be expected to be around 3-5 mils.
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