Cracked ring!!

[rabia218]

i did my pressing today and the ring came out of the furnace cracked and obviously the veneers came out in a strange shape too because of that! any ideas of what happened?!

 

[CaptainInsano25]

Have you done pressing much?? My first thoughts are that it's pressing cold.

 

[rabia218]

Have you done pressing much?? My first thoughts are that it's pressing cold.

i have been doing pressing for 5 years, what pressing cold means?

 

[CaptainInsano25]

I mean that it sounds as if you placed the ring in the porcelain furnace before the furnace was hot enough. Also, your air pressure may be too high...

 

[ninetofive]

Hi,today I tried pressing some e.max in a 100g ring in a whipmix pro press I recently bought second hand.There were only 2 crowns in the ring so I dont think thats an isssue but it split the ring.This is the 4th time its happened.I bench set the ring for one hour and burned it out for another hour.I have the regulator set to 4.5 bar and ive set up the furnace to the e.max press book.Any ideas people cos i've got no idea now?

 

[DevonR]

our pro press is set to 4 bar pressure...

i also use a disposable plunger

 

[ps2thtec]

Hi,today I tried pressing some e.max in a 100g ring in a whipmix pro press I recently bought second hand.There were only 2 crowns in the ring so I dont think thats an isssue but it split the ring.This is the 4th time its happened.I bench set the ring for one hour and burned it out for another hour.I have the regulator set to 4.5 bar and ive set up the furnace to the e.max press book.Any ideas people cos i've got no idea now?

I don't know what investment you are using but after one hour bench set is it going into a hot or cold burnout?

Also keep your waxup 10mm from the outer edge of the ring.


______________
"Yet another long series of diversions to avoid responsibility"

 

[KMoft CDT]

One hour bench set into a hot furnace is too long. What investment? Do you grind the tops on a model trimmer to release the steam? Something as simple as a plunger canted a bit when it's put in? I've even seen folks pull the sprue former out unevenly (and a little early) cracking the investment.
Is it only with 100gr rings
Give the hot ring a careful look when you're ready to press, ANY tiny cracks? Anywhere?

There's a lot of variables, but seriously double check your investment, sprueing and furnace instructions. (And if you can swing it get an EP5000)

 

[CaptainInsano25]

kmoft is right, there are a lot of variables. Another thought comes to mind-- You may not be mixing your investment long enough... 1 minute standard.

 

[BobCDT]

Hi
If you are using a speed burnout or ring into a hot burnout oven it's imperative that the ring goes in at the peak point of the chemical reaction. This exothermal reaction is generally around the 20 minute mark. You will know it because the ring will get very hot and should be put into the burnout when the ring is at its hottest. If you go in too early or late you can have rings splitting.
Bob

 

[paulg100]

If you are using a speed burnout or ring into a hot burnout oven it's imperative that the ring goes in at the peak point of the chemical reaction. This exothermal reaction is generally around the 20 minute mark.

That is not the case with the ivcolar investments, well at least the pressvest speed.

25min for inlays/onlays (less expansion)

45 mins crowns and veneers. By the this time the ring is stone cold.

These are the official set times.

it really does depend on the investment your using though.

never had a cracked ring yet. well not one that the ep3000's pressure sensor hasnt picked up anyway. but never had a misspress due to it.

 

[Tautvis]

It's Whip mix for you Get a descent pressing furnace. Ivoclar EP5000 would do or EP3000.