press ceramic cracking

[Dorian Dibra]

it happens often while i"m devesting the pressed ceramic it cacks near the sprue, somemes it comes out just perfect, any idea? is it a cooling problem?



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[ps2thtec]

It’s helpful to know what brand of ceramic it is. Are you following the basic rules of most ?

Letting the ring cool properly?
Devesting with the proper psi when blasting? Not too high?

 

[Dorian Dibra]

It’s helpful to know what brand of ceramic it is. Are you following the basic rules of most ?

Letting the ring cool properly?
Devesting with the proper psi when blasting? Not too high?

it is lisi press, i've tried celtra also but it happens the same. i put the ring out of the furnace at 300c temp and i devest when is totally cool. 1.5 bar of pressure when i see the ceramic. i try to follow the basic rules. furnace ep600 combi, could it be a malfunction of furnace even though sometimes the pressing is perfect?

 

[ps2thtec]

it is lisi press, i've tried celtra also but it happens the same. i put the ring out of the furnace at 300c temp and i devest when is totally cool. 1.5 bar of pressure when i see the ceramic. i try to follow the basic rules. furnace ep600 combi, could it be a malfunction of furnace even though sometimes the pressing is perfect?

Do you have the lisi tech manual….. here is the link

https://www.gcamerica.com/lab/products/GC_Initial_LiSi_Press/TMANUAL_GC_Initial_LiSi_Press.pdf

 

[FASTFNGR]

it happens often while i"m devesting the pressed ceramic it cacks near the sprue, somemes it comes out just perfect, any idea? is it a cooling problem?



[url=https://ibb.co/nkvpGR1] eliminate duplicates online[/URL]

Going back to pressing time, the was a rule for the size and the direction of the
sprue that determines the flow of particles after melting. It was as I remember 6mm sprue and yes cooling is a big issue. I never put on a cold and solid surface. I always put it on a metallic surface like the top of the burn out oven till it cools. Hope it helps.

 

[Car 54]

Are you using disposable plungers, or a Alox type of plunger?

 

[Mike2]

Looks like cooling issue as the mass of ceramic on that sprue is shrinking and pulling creating stress. I would lengthen the sprue and see if that solves it. My 2 cents

 

[Dorian Dibra]

Are you using disposable plungers, or a Alox type of plunger?

Disposable plungers

 

[Dorian Dibra]

Looks like cooling issue as the mass of ceramic on that sprue is shrinking and pulling creating stress. I would lengthen the sprue and see if that solves it. My 2 cents

I read the furnace manual again, it says when the press is finished and the furnace opens immediately remove the investment ring out of the furnace… it mean at 880 degrees. Is it logic?

 

[Car 54]

Disposable plungers

Good, as sometimes the Alox plungers can give you grief as far as the heat they maintain within the center, ingot area causing things to cool off at different rates.

 

[Car 54]

I read the furnace manual again, it says when the press is finished and the furnace opens immediately remove the investment ring out of the furnace… it mean at 880 degrees. Is it logic?

It's what I do with emax press, as soon as the head opens I set it on wire mesh tripod like the ones we used to use for soldering.

 

[CatamountRob]

Have you used e.max and had the same problem? I’m asking because I use e.max and I’ve violated every rule there is with regard to cooling short of quenching it and I’ve never had that happen.

 

[Car 54]

Have you used e.max and had the same problem? I’m asking because I use e.max and I’ve violated every rule there is with regard to cooling short of quenching it and I’ve never had that happen.

If I remember right, in a pinch using emax, you even used the brick press technique with success?

 

[Dorian Dibra]

Have you used e.max and had the same problem? I’m asking because I use e.max and I’ve violated every rule there is with regard to cooling short of quenching it and I’ve never had that happen.

i didn't try emax yet

 

[CatamountRob]

If I remember right, in a pinch using emax, you even used the brick press technique with success?

That is a fact. I’ve also sandblasted it when it was still extremely hot. You kind of have to work at creating a failure.
Normally I let it cool until I can pick it up though.