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Casting problem, plaster falls from flask


#1

i am a problem with the casting , can anyone help me to rectify the
issue. I am using the kerr plast 2000, plaster. After blending with
38% - 40 % of water to 100 gms of power. After blending it is
debubblezed, and poured into the flask, then dried natural for 45
minutes. Then kept in the dewaxer, the to burn out furnace starting
with 150 degrees, after the burnout cycyle when the flack is
mover/removed for powering the plaster falls like the flakes from
the flask.


#2
... After blending with > 38% - 40 % of water to 100 gms of power.

The investment to water ration is critical. Use the ratios
recommended by the manufacturer, EXACTLY as written.


#3

Try a longer time before steam dewaxing 1 hr 30 min or 2 hours. Then
make sure the steam dewaxer temperature is a little below 100 C. I
used to have problems with plaster spalling in a large steam dewaxer
till we set the temperature down to about 90 C. There will still be
plenty of water vapor just not quite as hot.

James Binnion
James Binnion Metal Arts


#4

… After blending with 38% - 40 % of water to 100 gms of power.

The investment to water ration is critical. Use the ratios
recommended by the manufacturer, EXACTLY as written. 

38-40% is within the manufacturers ratio for this investment

James Binnion
James Binnion Metal Arts


#5
i am a problem with the casting, can anyone help me to rectify the
issue. I am using the kerr plast 2000, plaster. After blending
with 38% - 40 % of water to 100 gms of power 

Nagesh, I would suspect the problem is either due to using the
De-Waxer or perhaps in the burn out cycle. Find a way to check the
temperature of your oven and make sure it is within the proper range.
We quit de-waxing some years ago due to it causing several different
investment problems. We haven’t had an investment problem since. You
might check to make sure the water-powder ratio is exactly in
proportion as well and make certain the investment is fresh… it
does get old.

Hope this helps. Dan.
DeArmond Tool
dearmondtool.com


#6
We quit de-waxing some years ago due to it causing several
different investment problems. We haven't had an investment problem
since 

When we started doing steam de-waxing we had lots of investment
issues too, bad surface finishes, spalling and cracking were not
uncommon. After a lot of experimenting we found that reducing the
temperature slightly got rid of the problems. I placed a
thermocouple probe in the chamber connected to a temperature
controller and kept the chamber at 190 F. Also making sure to allow
the investment to gain its full green strength 1.5-2hrs after gloss
off. Also not moving or disturbing the flasks for 1 hr after gloss
off proved to reduce investment issues.

Jim

James Binnion
James Binnion Metal Arts