emax pressing splitting

[S.Brink]

Hi, I'm having problems sometimes with my emax rings coming out of the furnace split. There's no common denomenator that I
can think of. I'm using a pro press 100 with programs for ant. and post. Posterior having a longer hold time. Doesn't seem to matter
whether it's anterior or posterior. Only happens once in a while, but always one that needs to go out soon! Right? Any suggestions?
Does anyone else have this problem?

 

[Rugardave]

Split Rings

Use good investment. Burn out with multi-stage and heat soak at 1200 for half hour then final temp. The cracks come from too fast heat rise and or
weak investment. Also your pressue could be too high, the lower the better. I'm at 3.5 bars or less with the Microstar HS.

Microstar is good and anything else from Germany.

 

[ps2thtec]

What investment are you using?

I swear by PCI plus. Look in your Zahn Catalog. It's made for pressing. Not Universal. Flawless!

 

[S.Brink]

I'm using galaxy 2 by Talladium for investment. I never used to have a problem until recently. The furnace is set for 4.5 psi, that's what whip mix
said to go by. I also use disposable plungers. Thanks.

 

[bullit]

Make sure burn-out temp. is right.(1562-1600) and hold for 1 hr. Be fast moving from burn-out oven to press-oven.
.

 

[doug]

I'd check the calibration on the burnout furnace. I'd also make sure that the investment is mixed for the required amount of time.

 

[Mike2]

I would agree with above, but if it is cracking during pressing usually means press oven problem. That does not mean that there aren't microfractures in the ring prior to pressing but I would check the pressure and calibrate the oven. Make sure you follow the set times on bench set prior to burn out to let steam escape.

 

[Zubler USA]

Cracking - Mixer (weak vacuum),investment (bad batch),bench set (not long enough),alox plungers (deformed) - these are ring crackers. It is rarely the furnace. If it is the furnace your pressure is way too high . If I recall correctly, a Pro Press 100 should be set at 4.25 BAR (63 psi),check your platform (TILTED TO ONE SIDE?),Does your press rod come down strait and smooth?.