Metal casting rings

[gold999]

It's been ages since I've used metal casting rings.
I've been having flash over on the metal collars and sometimes on the seating surfaces of Nobel Biocare gold adapts and 3i UCLA abutments.
The metal also goes inside the screw access hole form the top, but never to the screw seating surface - knock on wood !
I've thought of maybe trying the metal casting rings, which I used to use years ago.
I'm using ringless and have been burning out @ 1575* for 1 1/2 hours and using 20% special liquid for Bellavest SH investment and 2 winds on the centrifical casting machine.
I clean the collars with denatured alcohol and no wax pattern cleaner or debubblizer.
I'm using either Jensen JP1(54% Au) or Jensen Pulse N3((80% Pd)

 

[2thm8kr]

Before going back to metal rings. Try 1 1/2 turns on your casting machine. Casting pressure is often overlooked. In my casting days 1 ring was never heat soaked for more than an hour at high temp.
Just change one variable at a time until you get this figured.

 

[zero_zero]

It could be the investment if you're getting metal where it not supposed to go...

 

[Car 54]

Did this just start happening? Why is your liquid to water ratio so low on a abutment case? Maybe try 50-60% liquid?

 

[Big Guy]

Try turning your burnout temp down to like 1350-1400.... I would also think your ration has too much water get it closer to 50/50

 

[doug]

Are you doing the little cut-in at the interface of the wax and part? If not, that may solve the problem. We need a white board on here to draw examples of what we're thinking

 

[CatamountRob]

How are you spruing them? I used to sprue UCLA's on direct sprues and had problems, it goes much better when I use an indirect sprue.

 

[JohnWilson]

All good reasonable suggestions above but the number one problem people have with metal ceramics and implant restorations is the fact they use the same ratio of water to special liquid that they use for tooth born restorations which is a big no no. For tooth born cases you want expansion in the investment for implant restorations you want zero expansion to the investment. My suggestion is to go back to the instructions read what the manufacture recommends and stick to the ratio. Tight is right!

 

[zero_zero]

Tight is right!

We can all agree on that

 

[Mike2]

In addition to John's comment, if there is plastic involved with the ucla, make sure you lay ring on side to start. Doing this allows the gases of combustion to evacuate easily...plastic combustion is very violent at those high temps compared to wax. I get some of that flash with the milled waxes if i dont lay on side..my 2 cents

 

[escopche]

All good reasonable suggestions above but the number one problem people have with metal ceramics and implant restorations is the fact they use the same ratio of water to special liquid that they use for tooth born restorations which is a big no no. For tooth born cases you want expansion in the investment for implant restorations you want zero expansion to the investment. My suggestion is to go back to the instructions read what the manufacture recommends and stick to the ratio. Tight is right!

Don't you need to use 50% special liquid for strength? If I use less than that I would defiantly get cracks(Microstar).

 

[rkm rdt]

I tried using the white out trick and it worked great. Try painting the interface.

 

[gold999]

Before going back to metal rings. Try 1 1/2 turns on your casting machine. Casting pressure is often overlooked. In my casting days 1 ring was never heat soaked for more than an hour at high temp.
Just change one variable at a time until you get this figured.

Thanks I know changing multiple things - you never know which one worked !

 

[gold999]

Did this just start happening? Why is your liquid to water ratio so low on a abutment case? Maybe try 50-60% liquid?

It's been happening for a while now and I know it's something I'm doing. The 3i UCLA the other day and this NobelReplace goldadapt - no room for error. The Nobel active gold adapts you have some room for some flash if it happens, without a big headache ! I guess the way I was looking at it - more special liquid means more expansion, so tried to keep that as low as to what's recommended.

 

[gold999]

Try turning your burnout temp down to like 1350-1400.... I would also think your ration has too much water get it closer to 50/50

OK Thanks I'm going to try one thing at a time and see which one works

 

[gold999]

How are you spruing them? I used to sprue UCLA's on direct sprues and had problems, it goes much better when I use an indirect sprue.

I'm using the sprues with reservoirs already attached and always weigh the patterns and add alloy accordingly

 

[gold999]

In addition to John's comment, if there is plastic involved with the ucla, make sure you lay ring on side to start. Doing this allows the gases of combustion to evacuate easily...plastic combustion is very violent at those high temps compared to wax. I get some of that flash with the milled waxes if i dont lay on side..my 2 cents

I've never heard of that - interesting !

 

[gold999]

All good reasonable suggestions above but the number one problem people have with metal ceramics and implant restorations is the fact they use the same ratio of water to special liquid that they use for tooth born restorations which is a big no no. For tooth born cases you want expansion in the investment for implant restorations you want zero expansion to the investment. My suggestion is to go back to the instructions read what the manufacture recommends and stick to the ratio. Tight is right!

For tooth born restorations I'm using 60 - 70% special liquid and for the implant cases I'm using 20% special liquid which is what Bego recommends the lowest that you go. Years ago when I first started casting Nobel Biocare's gold adapts, we were using Jensen's Classic IV and using a low burnout and never had an issue.

 

[gold999]

Are you doing the little cut-in at the interface of the wax and part? If not, that may solve the problem. We need a white board on here to draw examples of what we're thinking

Oh I think I know what you mean - like an indentation in the wax, UCLA gold collar interface. I haven't tried that, might be something to try

 

[CatamountRob]

I'm using the sprues with reservoirs already attached and always weigh the patterns and add alloy accordingly

I thought so. You might try a small bar instead.