ring cracks

[kiter73]

Greetings!Newbie here !I have just started press e.max .playing around with settings as temp and time.Finally no misspress but much reaction layer .I will play with press time later ,but the problem is small cracks filled with the during pressing and after divesting where the crack was the shade is different than the rest of the crown.first i thought a crack but no.Everything i use ivoclar 5 bar pressing pressure .How to avoid cracks?

 

[Gru]

Kiter73: Welcome! There are almost an endless number of posts on various threads for emax and investment issues. You may find all you're looking for (and much more that you aren't) by searching the threads. Otherwise, answer the typical questions you will be asked: calibration, oven types, investment types, etc. But save yourself time and check out the treads! Good luck!

 

[ps2thtec]

Sounds like you are describing the line opposite the sprue that lacks chroma. Something most pressing emax have seen. It's the material joining together after flowing around. Not a crack.

 

[user name]

Greetings!Newbie here !I have just started press e.max .playing around with settings as temp and time.Finally no misspress but much reaction layer .I will play with press time later ,but the problem is small cracks filled with the during pressing and after divesting where the crack was the shade is different than the rest of the crown.first i thought a crack but no.Everything i use ivoclar 5 bar pressing pressure .How to avoid cracks?

"How to avoid cracks"...

1) Start with the press sold by Ivoclar...the maker of the product youre trying to use.
2) Get a good press from a company like Zubler that has gone above and beyond doing researh on how to successfully press and has equipment preprogrammed.
3) Read and search this site. Every mistake has already been made and answered.

Good luck. I see this is your first post. Its nice to do an introduction first so we can say hi. Im Bob...Ill be pissing you off soon enough. Welcome!

 

[DMC]

 

[kiter73]

Thank you!

 

[chromecobalt]

5 bar pressure is a bit too much, 3-4 is ideal and use pressure pot to make the investment more dense and bubble free. After I started using pressure pot the waiting time of 40 min is now 15 mins and the cracks are non existent. Please give it a go.

 

[kiter73]

I was wondering to use pressure for investing but the ivoclar guide says no no.I think the temp is too high.This was my 4th pressing so i have so much to learn about emax.The bad thing is i just started my own full lab not much money left and no doctor so far.It is very hard to dial in the temperature see the $20 ingots going bad every time.Ineed to dial in fast

 

[user name]

I was wondering to use pressure for investing but the ivoclar guide says no no.I think the temp is too high.This was my 4th pressing so i have so much to learn about emax.The bad thing is i just started my own full lab not much money left and no doctor so far.It is very hard to dial in the temperature see the $20 ingots going bad every time.Ineed to dial in fast

Please answer...what pressing oven, investment, plungers are you using?

 

[kiter73]

Thank you for helping !I am in dental lab 20 years now as employed and now i got some money to start my own.i have Qex pressing furnace ,speed investment ivoclar,ALOX plunger .Started out pressing on 930 and only pressed the sprue nothing else ,next was 940 ,i had half crown .Boosted up to 980 than too much RL .that all was in 100 g ring .I made a 3 unit in 200 ring on 980 and the pontic did not came .I thought the tem still wrong so gave 995 .I know these all too much but i think when i had a misspress on the pontic i sprued like metal.Now i made a 200 ring 3 unit lower to 950 8 min press 30 hold pressure about 4.7 .See what i will get .The furnace pretty new wife said waht ever she build bake nice so the calibration seems fine but as soon as i get better result with pressing i check the calibration.Thank u for the help!

 

[user name]

Those temps are way high. Double check your press and make sure that the muffle heats up to 915-925 celcius (not fahrenheit) BEFORE the press starts. Im not familiar with your press, but we should be able to solve this. Your burn out should be 850 celcius, or 1562 F. If you are getting the burnout hot, and holding for 1 hour, then the heat in your Qex is the next step. If thats correct, then its a pressure or time issue. 4.3-4.5 bar pressure is good. Double check that you dont have leaks in your air line between the regulator and the press.

We need someone with a Qex to jump in here and run through the settings for you. I know youre no dummy, but often its the smallest issue that slips by and causes problems. Im anxious for you to get this fixed. I know youre frustrated....but just wait. E.max is so awesome its going to amaze you. Best luck!!

 

[ed 3]

never had any cracks for many years. something been done that out of specified on the instruction of the investment powder.

 

[Alistar]

Sorry to hear you have a QEX.

We made the mistake of purchasing that oven for pressing to save a couple bucks about two and a half years ago. We wasted countless hours and hundreds of dollars of materials like you trying to dial that thing in.

If you want to save your sanity. Ditch that thing and get a new press oven....it's not properly designed for pressing lithium disilicate.

Sent from my DROID RAZR using Tapatalk 2

 

[ps2thtec]

kiter73, I had a similar oven (Pentron Autopress) like the Q50. I followed the numbers in the green emax manual that I hope you have, on page 60,follow EP500.
The H listed is for H1. The H2 on your oven is the press time. I used 5:30 for a 100gm ring,, 7:30 for 200 gm.
When using that oven I put the pellet&plunger in the ring and left in burnout oven while press oven climbed to the
"T"2 and when press oven opens move your ring . Hope the burnout oven is only a few steps away. 4.5 bar.pressure .
I had very minimal reaction layer. Also used disposable plungers. They don't absorb heat.
.Follow the sprueing directions also about the 10mm rule, page 21.

 

[user name]

Just a thought...You are filling the rings and using the leveling caps...? Long shot, but if you were filling just over the patterns like a casting, that would lead to lots of problems. Just askin. You never know.

 

[kiter73]

Finally i have created a good one not much Rl on it .Sprued good .I have a cheap ring not the leveling one .I make sure it is leveled all the time and sand paper the top.The temp was 965.I probably drop another 5 celsius and less pressing time .I still had some crack inside and dthe glass pressed in so it is still hot.At least i am close.This picture taken after the ultrasonic bath.

 

[kiter73]

I was wondering to get a cheap scanner cercon eye for begining.I know it is basic but what else i can afford at this moment.Should i buy one or what other solutions are out there to make zircon frames?

 

[kiter73]

What wax should i use to model the crown ?The margings are not too perfect i would like to get some idea what wax would be good creating good margins.

 

[Trudy Peach]

Call Microstar and get a sample of their Lightstar wax. It is an all in one wax for dipping, carving and margins it was created by a technician. Here is their number 800-313-6427