Disposable plunger = Incomplete press ?

[sndmn2]

Just wondering if anyone else is having this problem. I'm getting moon craters on the surface of my pressings with disposables. Margins are complete . I don't think the disposable are large enough. Real close but not as tight as an alox. The press material is climbing up the walls of the plunger. I think this is adding additional resistance and sending a message to my Ivoclar oven that the press is complete. Any thoughts ? Thanks.

 

[Car 54]

I've had that before, where it (emax material) even came up to the top of the ring. Since it was only a single unit, and I caught it in time (the plunger distance going past normal) I stopped it and was able to use the unit. I had previously been using plungers from Zubler, with no problem, then went to Microstar, and started having problems. I believe they both get them from the same place (Microstar?) but the Zubler rep said theirs are better, more consistent. I'm not sure if it is sales pitch or not. I do still get some creep up the side of the Zubler plunger once in awhile, but nothing that would make me want to switch back to alox plungers and their higher reaction layer.

I also bought some new tops and sprue bases from Ivoclar, just in case my old ones were wearing out and causing there be more space between the plunger and the side walls. When I see it pressed good, I mark the bottom of the ring "good" with a Sharpie, so I'll know on following presses if there is a higher creep issue, it's the plunger (I use Microstar for large rings, and Shofu Ceravety for small rings).

 

[biodentg]

Just wondering if anyone else is having this problem. I'm getting moon craters on the surface of my pressings with disposables. Margins are complete . I don't think the disposable are large enough. Real close but not as tight as an alox. The press material is climbing up the walls of the plunger. I think this is adding additional resistance and sending a message to my Ivoclar oven that the press is complete. Any thoughts ? Thanks.

Hi, what model of IVO furnace is this?

 

[user name]

The 'craters' are from over heating the material during the press. This also reduces the viscosity and makes it more difficult for ovens to sense resistance and stop the press, resulting in material creeping up around the plunger.

 

[user name]

The 'craters' are from over heating the material during the press. This also reduces the viscosity and makes it more difficult for ovens to sense resistance and stop the press, resulting in material creeping up around the plunger.

...Unless youre a dope like me and use an 11mm plunger instead of a 13.

 

[sndmn2]

Hi, what model of IVO furnace is this?

Ep 5000

 

[sndmn2]

The 'craters' are from over heating the material during the press. This also reduces the viscosity and makes it more difficult for ovens to sense resistance and stop the press, resulting in material creeping up around the plunger.

Does the alox plunger pull some heat away from the pellet? Just wondering if I should lower my press temp when using a disposable.

 

[biodentg]

I know Patrick is not going to like this, but pressing this way has solved many issues for me.
Picture is self-explanatory unless, anybody wants extra info.
IVO furnaces press to perfection, perhaps you only need to calibrate temp.

 

[pjd cdt]

Does the alox plunger pull some heat away from the pellet? Just wondering if I should lower my press temp when using a disposable.

I would star there. Most things we do in the lab come down to time and temperature. How much energy is required to press this pellet?


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[sndmn2]

I know Patrick is not going to like this, but pressing this way has solved many issues for me.
Picture is self-explanatory unless, anybody wants extra info.
IVO furnaces press to perfection, perhaps you only need to calibrate temp.

Actually I tried that. I calibrated my oven and checked the burnout also . I will try pressing my LT pellets on the HT cycle. The HT cycle is 9 degrees lower.

 

[aqdental]

Does the alox plunger pull some heat away from the pellet? Just wondering if I should lower my press temp when using a disposable.

Yes, alox require more energy (heat) and you should lower your final temp ( 5/10 deg. Celsius). Try 5 first, is still too hot lower extra 5. Material is over heated, becoming more fluid and start climbing the gap between plunger and ring (so your furnace does not stop the pressing because plunger is still moving). 300 microns is the standard that ivoclar recommends for pressing e.max. You can change that and have the plunger stop earlier, but it should not be necessary. A well heated ingot and a snug fitting plunger will abort the program as soon there is no more than 0.3 movement in the plunger in 30 seconds. If not happy with current disposable, make your own: you can adjust the size of them by % of liquid used in the mix of investment ( duplicate some alox with silicone).

 

[Car 54]

...Unless youre a dope like me and use an 11mm plunger instead of a 13.

or in my case the opposite, using a Empress base and trying to fit an emax ingot into it...it took a bit of grinding that puppy down to get it to fit

 

[Patrick Coon]

I know Patrick is not going to like this, but pressing this way has solved many issues for me.
Picture is self-explanatory unless, anybody wants extra info.
IVO furnaces press to perfection, perhaps you only need to calibrate temp.

I definitely wouldn't recommend the first photo with the used ingot in the mix. But as for the second picture with just the sliver of the disposable plunger in between the AlOX and the ingot I can't officially recommend it, but if it is working for you and you are happy with your pressings, keep doing it.

 

[rkm rdt]

...Unless youre a dope like me and use an 11mm plunger instead of a 13.

Have you tried pressing with the air compressor valve shut off?

 

[Car 54]

Have you tried pressing with the air compressor valve shut off?

That's why I loved when I switched to the EP600 with the mechanical plunger, as that did happen to me with the old empress press, (my Pentrons Auto Press Plus is air driven also),in my case forgetting to turn the compressor on

Maybe I shouldn't be admitting all this..as you "guys" might "vote me off the island"

 

[rc75]

I sell 13mm disposable plungers (Box of 50) for $45. Item number T-029L

 

[biodentg]

I definitely wouldn't recommend the first photo with the used ingot in the mix. But as for the second picture with just the sliver of the disposable plunger in between the AlOX and the ingot I can't officially recommend it, but if it is working for you and you are happy with your pressings, keep doing it.

I knew you wouldn't like it, but..... with the first picture I can press 0.90gm to 1.10gm in a 200g ring and I'm sure the old ingot stays in the sprues.
As for cracks at the bottom running into the units, they are gone forever. I adopted this technique after using the multi ingot.

 

[sndmn2]

...looks to be another issue.....What could cause this crater effect ? Calibrated oven.. Checked burnout... EP5000... Appears to only happen on the labial side of the crown. Press Vest speed.

 

[Patrick Coon]

...looks to be another issue.....What could cause this crater effect ? Calibrated oven.. Checked burnout... EP5000... Appears to only happen on the labial side of the crown. Press Vest speed.

Can you send me some clear photos (from different angles) of your pressing still attached to the sprue base? This will let me evaluate exactly what is happening. Either post them here or send to me directly:

[email protected]

 

[user name]

...looks to be another issue.....What could cause this crater effect ? Calibrated oven.. Checked burnout... EP5000... Appears to only happen on the labial side of the crown. Press Vest speed.

Appears to only happen on the labial...in other words, the side facing the exterior of your ring. No?

Too hot.