Pentron Autopress Plus furnace + Emax

[envisiondental]

If anyone here's pressing Emax with this furnace I'd really appreciate some tips.. tomorrow I'll be pressing Emax for the 1st time. Couple questions..
1. Pressing cycle paramaters.. I'm sure they are in the
manual but if someone has some tweaked ones that'd be
great.

2. With 3g they recommended having the pressing furnace righ next to the burnout.. I'm sure it's the same.. but would it be a big deal to have the furnace 20ft away? or a 5-10 second walk?

3. I don't have the acid yet.. How necessary is this.. will sandblasting take off the reaction layer? I heard the acid just makes the reaction layer visible so it can be blasted off?

Anyway.. any tips would be greatly appreciated.

Thanks in advance.
Bill

 

[Gdentallab]

If anyone here's pressing Emax with this furnace I'd really appreciate some tips.. tomorrow I'll be pressing Emax for the 1st time. Couple questions..
1. Pressing cycle paramaters.. I'm sure they are in the
manual but if someone has some tweaked ones that'd be
great.

2. With 3g they recommended having the pressing furnace righ next to the burnout.. I'm sure it's the same.. but would it be a big deal to have the furnace 20ft away? or a 5-10 second walk?

3. I don't have the acid yet.. How necessary is this.. will sandblasting take off the reaction layer? I heard the acid just makes the reaction layer visible so it can be blasted off?

Anyway.. any tips would be greatly appreciated.

Thanks in advance.
Bill

i press at 917 *C 15 min but noy with this furnace.
that's the recommended, but my burn out furnace is about 15 ft away, and no broblems till now.
the acid is necessary, it will make the reaction layer more easy to be removed.

my only tip is to use a good investment.

 

[TheLabGuy]

917C 15min <<<is that your press time or hold time?....100, 200, 300 gram ring?

 

[envisiondental]

Well I tried and I failed... BIGTIME!

I'll give a rundown and the problems I ran into.. and hopefully I'll figure this out.

1. Waxing and investing.. no problems.. I used Aurivest from Aurident.. no cracks or anything throughout the whole process.. solid as a rock.

2. I found out emax pellet size is a hair larger and it wouldn't fit ring designed for pentrons 3g.. and after adjusting the pellet's perimeter slightly it dropped right down in there like it should.

3. After I transferred the ring to the porcelain furnace and hit start.. it went up.. but it wanted vacuum. I read nothing in the pressing parameters about needing vacuum. My other vacuum wasn't close and was in use so I went ahead and hit esc and let it continue without. I figured these were just test cases and I just wanted to see a successful press.

SO after all this I heard the bang from the furnace.. it came down.. I divested and it only pressed about 1/3rd of the crowns.


I'm thinking.. 1... after adjusting the pellet to fit in the ring the investment had cooled too much even though I had put it back in the furnace the 3 times I checked to see if the pellet would drop in.
2. The vacuum helps the press... and I didn't use vacuum
3. I need more air pressure.. there is an air pressure adjustment on the air input to the pressing furnace... not sure what it's set at.. but maybe it needs to be higher.

4. I pressed at 920... 5 degrees hotter than documented. I always had to fire my D. Sign porcelain about 20+ degrees higher than the documented temps for the porcelain to fire correctly.. maybe I need to bump it that far up at least.


Anyway that's about it.. I know it's a holiday weekend but this is gonna bug me so I'm going in to get this resolved... any input would be greatly appreciated.
Bill

 

[TheLabGuy]

Your pressure should be 67 lbs/sq.in or 4.5 bars
What is your hold time and press time? What kind of ring are you using? Small ingot?
....and yes, you need vacuum, and you shouldn't leave your ring sitting outside the burnout oven for more than 30 seconds before pressing (I think that was the time I read somewhere).

 

[charles007]

Hey LackofVision....just kidding..hehe !!! Go to the Ivoclar website and read thru the emax press manual carefully. Its the little things that can cause bad problems when pressing.
I have the ep5000 oven, so take my advice with a grain of salt !
Press the first case with the 3g program, then adjust from there... at least that will be a starting point to make adjustment. Also check out the temps,etc on 3g compared to emax LT... I'm assuming your pressing LT, and with Rob's help maybe you can press this case over the weekend..

Hopefully you can get the correct adjustments early Tue. morning from Pentron...Slim chance Ivoclar will give you much help.

 

[envisiondental]

Thanks for the replies..
I'm using the small lt pellets and 100g ring. Can't figure out why I didn't notice it but my burnout furnace was only at 1450.. not 1569.. that could be the culprit.. I'll raise that and also raise the pressing temperature on the pressing furnace 20degrees and also have vacuum working... then hopefully I'll be there. psi was at a little over 70lbs so I was good there.
Well .. here I go again.. and yeah I'll be studying the emax instructions a bit during burnout.

Thanks

 

[TheLabGuy]

For a 100 gram ring, I'm holding for 15 mins when final temp is met and then pressing for 8 minutes. Not sure if your oven allows for those two parameters but they should.

 

[envisiondental]

Well... finally success! I failed one more time but 3rd time was the charm. Had to raise my pressing temp to 945! Darn my furnace. Anyway now I know what a reaction layer is and I wish I had some acid. Anyway.. thanks for the input people.

 

[gzarrov]

Would you post all your settings please???

 

[dmonwaxa]

Pentron AutoPress' Plus

T1 700*C
T2 925*C
Rate 60*C
H1 15Min
H2 10Min
Air Press 75lbs

100/200gm rings, and LT Ingots. Not quite tweaked yet though.

" EnvisionDental" you might want to invest in the emax rings if you haven't already.

Hope this helps.