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2. DIRECTIONS
Duplicate master model using a suitable
duplicating material. Use a good quality duplicating material
to avoid rough model surfaces .
MODEL
Mix water and the special
liquid in desired proportions to obtain proper expansion for
the casting alloy. Generally, a mix of 50% liquid and 50%
water would provide adequate expansion and a smooth model.
Mix 14 ml liquid with 100 grams powder
for 30 to 60 seconds under full vacuum with a low speed mechanical
mixer ( 300 to 450 rpm). Pour the mix into the duplicating
material under gentle vibration. Allow the investment to set
and become hard for about one hour before separating the model
from the duplicating material. Use reverse spruing through
the model using sprues of appropriate length and diameters.
This will eliminate necessity of cutting through the hard
investment.
Dry model in oven at 200 to 250 degrees
Fahrenheit for about 60 minutes. Dip the model into wax or
rosin at 200 degrees F while the model is still hot. A good
model spray can also be used to prepare the model surface
for later wax up. Replace models in drying oven to absorb
any surface rosin or wax on model surface. Remove model and
blow off excess wax. You are now ready for wax-up.
PAINTING AND INVESTING
Mix desired amount of CHROMECAST
- XF in proportion of 14 - 15 ml water or a mixture of water
and the special liquid to 100 grams of investment. Again it
is better to mix under vacuum with a mechanical mixer at low
speed for 30 to 60 seconds. A liquid mix of 75% water and
25% special liquid will give a smooth and clean bubble-free
casting .
Paint pattern with the investment
and then gently fill the casting ring by pouring the investment
from the sides of the ring under gentle vibration. You can
also use liquid investment sold separately by other vendors
for painting purposes .
The mechanical mixing under vacuum
is the preferred method. Either a one piece or a split ring,
removable type can be used. It is not necessary to have a
casting ring around the investment during burnout or the casting
.
BURNOUT & CASTING
Allow flask to bench set for one hour before burn-out.
Place flask into a cold burn-out furnace and heat to 500
degrees Fahrenheit in 45 to 60 minutes; then raise the temperature
to 1700-1800 degrees Fahrenheit over the next 60 minutes.
Heat soak for about 30 minutes and cast as usual.
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