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Hello everybody,
I made an 800 silver ring using the lost wax casting technique, the result was that there was a bit of material missing inside the ring, as if there was a void. I wonder what went wrong, thanks in advance for the replies.
https://0x90.it/uploads/missing_mate...e_the_ring.jpg
I made another ring and it always has the same problem: lack of internal material. Another problem that has occurred simultaneously with the other is the following: in the outer part of the ring there is the presence of porosity with a lack of material and porosity with excess material. Can someone help me? I would be very grateful to him.
https://www.0x90.it/uploads/m1.jpg
https://www.0x90.it/uploads/m3.jpg
What was the ring model made from ? It could be incomplete burnout.There is still ash sat inside the mould. I think there is a couple of things going on here. What ratio did you mix your investment at and which one did yo
u use ?
The model of the ring was made of wax. To remove the wax, I use the same oven for firing the flasks, I put the flasks with the hole downwards raised in a small metal tray so that the wax drains inside it, at 500 degrees centigrade I open the oven, I remove the tray and turn the flasks with the hole upwards letting the cooking proceed up to 790 degrees centigrade. Usually 40% water, but since it was too liquid I put a little more powder to not make it excessively liquid. The investment I use is Gold Star Omega+.Quote:
Originally Posted by josef1
I usually set the kiln for a slowish ramp (0 to 230 in about an hour and a half) upto 230 deg C then hold it there for around another 2 and a half hours until you ramp to flask temp then drop and hold to flask casting temp. If you go to hot at first you will boil the wax and it gives bad results by breaking down the mould . Also stick to the mixing instructions for the investment. If you use a 3" x3" flask for example there will be 1024 grams powder to 406 grams of water ish. Its important to get it all mixed in 8 mins. there is instructions on the website but its 4 mins mixing ,1 min vac bowl, 1 min pouring then 2 mins vac the flask have a practice at this its like cooking you got to get your timings right lol. https://www.ransom-randolph.com/flask-calculators there are some helpful powder flask ratios here but 40:1 is correct for your powder. I leave my wax flasks with the button facing down for the duration. will help you get quantities right so you don't mix to much investment. If you get stuck private message me and can have a chat if that helps.