I'm new in casting i don't no how to use oven i have heard it need to
keep different timing for different temp and different gold like 14k,
18k and 21k yellow and white gold 18k.
please advice if anybody have chat.
Investment powder manufacturers recommend various burnout cycles.
Please visit their websites for the burnout cycles. For Programming
the programmer which programmer are you using in furnaces. Before you
use the program please ensure what is the ramp the powder can
150 Deg C 2hrs, hold for 2hrs, 270C one hour hold for 2hours, 400C
one hour hold for two hours, 550C one hour hold for 2hours, 630C one
hour hold for 2 hours, If wax set do not go above this temperature.
If no diamonds are set go to730 C hold for 2hours. Casting
temperature of the flasks 650 C hold for 2hours.
Burnout cycles should be the same whether casting silver or gold.
Platinum is a different matter and needs its own specialised
investment and casting equipment.
My usual burnout cycle for casting silver in 90mm flasks in a vacuum
casting machine is as follows:
Ramp up to 150C and hold for 2 hours with the vents on the kiln open
Ramp up to 400C and hold for 1 hour
Ramp up to 500C and hold 1 hour or until burning wax fumes stop
Close the vents on the kiln and ramp up to 650C (absolute maximum
700C) and hold for 3 to 4 hours
Ramp down 450C and cast
I extend the soak time at 650C for 4 hours when burning out organics
such as leaves and seed pods. 3 hours is fine for wax patterns. Check
the sprue base of the flask. If it is white or very light grey you
should have a clean burnout.
I usually cast at 450 though sometimes 500 is advisable for castings
with fine details. Otherwise I cast the flask with finely detailed
stuff first on the assumption that the core temperature of the flask
would be higher than the kiln temperature. I take 700C as the
absolute maximum soak temperature because the gypsum in the
investment will start to break down at 730C leading to rough
castings. With my current setup 650 consistently gives me a clean
burnout and saves on electricity consumption.
If you are using smaller flasks such as those typically used for
centrifugal casting you can get away with shorter stages in the ramp
up to soak temperature.
If you live in the US you may have to convert my figures to those
funny American degrees.
All the best
Using Kerr's Satin Cast The first temperature is 300 deg. F, for two
hours once it reaches temperature. The next is 700 deg. F, for two
hours once it reaches temperature. The final burn out temperature is
1350 deg. F, for four hours once it reaches temperature. After burn
out is completed the casting temperature is 900 deg. F to 1100 deg.
F, for one hour or more once it has reached temperature. At this
point I cast. Good Luck,
Here is what I have hope it helps
General rule for investment/water ratio: while cupping the end of
the metalflask with one hand pour water into the flask to two-thirds
level; empty this into the mixing bowl. Proceed to fill the
investment until it reaches the top of the water level.
Flask up to 65x65 (mm)
1 hour - 155 C
2 hours - 155 C
1 hour - 430 C
2 hours - 430 C
2 hours -735 C
3 hours - 735 C
1 hour - lower to casting temperature
1 hour - lower to casting temperature
FLASK CASTING TEMPERATURES
aluminum 204 C
gold 10kt white 535 C
berellium copper 420 C
gold 14kt (585) yellow 480 C
bronze 480 C
gold 14kt (585) white 520 C
gold 10kt yellow 520 C
platinum 760 C
silver 425 C
Andy The Tool Guy
Have a Stullerific Day
One of the things I learned through experience in casting is the
need to keep the investment dry by storing in a well sealed container
and of precision in the proportion of investment to water. The
manufacturers of my investment, Gold Star Ultra specify an investment
to water ratio of 38% to 42%, the thinner mixture for intricate
castings and the thicker for heavy ones. I usually split the
difference by making the water 40% of the weight of investment. For a
85 by 110mm flask I add 750g of investment powder to 300g of water,
in my case rain water. I measure both the investment powder and water
by weight using digital scales that read to one gram. This is a more
than adequate level of precision.
I mix my investment in 2 litre ice cream tubs which fit comfortably
in the bell jar for debubblising. I add investment to water and mix
with a spatula until the mixture is smooth and free of lumps. It
should look and feel like a crepe batter I start a countdown times
set to 8 minutes as soon as I add the investment to water. I
debubblise in the tub for around two to three minutes. Watch for the
mixture to firstly rise and then subside somewhat.
When it bubbles look a bit like cooking porridge then the mixture is
I then pour the investment into the flask and debubbilise the flask.
It is important to keep an eye on the timer and ensure the flask is
out of the vacuum and the top of the investment smoothed over by the
time 7 minutes have elapsed. A handy feature on my timer is a three
minute warning beep.
As a note of warning remember that the silica powder in investment
is potentially carcinogenic so wear a mask with proper dust filters
when handling investment particularly when it is dry. Disposable
paper masks are really not good enough.
I keep my soak temperature when burning out below 700C, usually 650.
I find this consistently gives me a clean burnout. The manufacturers
of the investment I use specify the maximum soak temperature as 735C
but to me this uncomfortably close the point where the gypsum in the
investment starts to break down (around 750C)
After all this you just have to decide what incantation to casting
goddess works for you as you pour the metal.
All the best