Hello, two things strike me when I read your description of your
casting process, the first is how low your flask temperature is, the
second is the time you wait before quenching, although this is most
probably related to your low flask temperature and the quick freezing
of the castings that this will result in. If we start at the
Metal temperature, your quoted value of 1800F is good. In general I
might recommend starting a little higher at 1820F, but each machine
is slightly different and if you have good fill at 1800F then you
obviously have the alloy fluid enough for the size of pieces you
Flask temperature, you quote 700F. This seems very low to me.
Generally I would be recommending flask temperatures in the range
850-1050F, dependent on the section size you are casting.
Finally, time to quench. I recommend removing the flask from the
casting chamber within one minute of casting and then waiting for 25
minutes before quenching out the flask.
I hope that this assists you with your next set of castings and
please feel free to contact me directly if you have any further