Cracked rings

[JohnWilson]

We had a very frustrating morning in our EMAX department that cost me a bunch of money. We had 5 200 Gram rings fracture on us today. 3 of the 5 failed in the oven and 2 had hairlines that we pressed and they failed.

We follow all of the steps with EMAX by the book we the only exception of utilizing Formula one for our investment. Our powder/liquid ratios are spot on as we use Whipmix equipment to weight and dispense the special liquid and water precisely. Or vac mix machine is programmable as well so I know nothing has changed. I invested in all of this equipment to maintain accuracy across the board from tech to tech no matter who was doing the investing.

Of course we are following whipmixes investing instructions to the T as we always have and just so you guys know we use all of Ivoclars silicone rings and spru formers.

A side note ee invested and cast 5 ceramic alloy rings today with no trouble or cracks with the same batch of investment

At first thought I felt that we got a bad batch of special liquid that froze but that does not appear to be the case. I questioned and questioned the tech today with no apparent issues. This tech has had a 99% success rate with our pressings over the last quarter s oI know he does everything by the book.

I am pulling my hair out on this as I can't stand to not know why something fails, after analyzing this back and forth I figured I would post it here to get some ideas what could be going on.

In the mean time I ordered a box of Ivoclars speed investment new plungers new spruformers/ring many of these items I need to add on as we are pressing more and more rings a day but I figure I would cover all the bases.

Any ideas?

 

[araucaria]

I don't do emax but investment principles are all pretty similar across the range I'd have thought. First for me is to check the furnace temperature (calibration?) and rate of climb. Moisture content - waiting before put in furnace. Position in furnace. Then back to powder and liquid condition, how is it kept and is the liquid affected by temperature - time of day in lab for mixing, is there an environmental change? Is the vac-mix unit pulling vacuum properly? blockage? Contamination??
Good luck with the quest - problem solving is a very valuable aspect of our profession, and the time we can potentially save is worth a lot of money to us.

 

[AL1]

I use microstar HS. I let it sit for 20 minutes before putting into a 1562 degree oven. Just before putting into the oven, after taking out of the ring, I let it sit for a few seconds and I can see the steam coming off the ring.
Sometimes if there is to much moisture in the ring it can cause it to crack. I have noticed hair line cracks every so often but the emax presed fine.
Hot ring into hot oven.
cold ring into cold oven.
This is what one of the manufactures told me.
I also do not use leveling cap, I mark the inside of the ring where the ridge is and fill to there then put it on a level surface and do not disturb it until it is set.
I am guessing that also helps some of the excess moisture escape.

 

[dmonwaxa]

John, since you invested using the same investment for casting and observed no cracking it would lead me to believe its the pressing oven. Re-check all parameters for the pressing program; hold and press time. Could be the plunger, make sure there is no debris on the pressing platform that would cause the ring to sit unevenly; just some thoughts. Sorry to hear you had a rough day.

PS: Check the air pressure; make sure that hasnt changed and not too high.

 

[paulg100]

Its stories like that which makes me glad i paid the extra $ for the ivoclar press with auto crack detection.

Hopefully when the time comes it works like its supposed toray2:

 

[JohnWilson]

Thanks for the tips guys

Troy of course calibration was the first thing I was thinking as well however it was the large rings that failed in the "" that had me pulling my hair.

The two that failed in the pressing oven had hairline cracks when they were finished with the burn out program but we attempted to press them anyhow. I have seen these types of cracks from time to time on other pressings with no issues.

I am so crazy anal now on the re waxed up rings that I had the tech change all the investment to a new box of Formula one/ change all the liquid in the dispensing machine and put new water in the machine as well. Like I said in the original post I have more new materials coming but I have to press these before the batch arrives.

All machines have been checked and everything appears to be as it should.

Sometimes I hate being the boss!!!

Wish me luck,

 

[Al.]

They all failed in the burnout oven so you can take the pressing out of the mix.

Is this the same box of investment you have been using with sucess or a new box.
Could be a malfunction in the Aquaspense?

One important thing I have noticed is in the winter my rings set up much slower. I do a slow burnout so normal seperation time is min of 1 hr, but in the winter they are NOT ready to seperate in the normal 1 hr time so I give them at least 30 min more. Here I think the same would apply to the fast burn out.

 

[JohnWilson]

Guys please read the post, the majority of the failed rings failed even before they got in the pressing oven. They failed in the burnout

I have the 2 original press from back in the day its still rock solid but I am looking to purchase a new one.

Thanks again for the suggestions

 

[araucaria]

During Christmas and NewYear closures was the heating turned off? Sometimes the storage zones can be colder than the room-temperature and the chilling as Al mentioned can be destructive to delicate materials. One way to counter this is to have liquids stored in large polystyrene boxes for insulation - some aquarium supply companies have these for fish protection. Powders benefit from being used when at normal room-temp, the setting reaction can take place as designed. another 2c

 

[JohnWilson]

They all failed in the burnout oven so you can take the pressing out of the mix.

Is this the same box of investment you have been using with success or a new box.
Could be a malfunction in the Aquaspense?

One important thing I have noticed is in the winter my rings set up much slower. I do a slow burnout so normal separation time is min of 1 hr, but in the winter they are NOT ready to separate in the normal 1 hr time so I give them at least 30 min more. Here I think the same would apply to the fast burn out.

Al I am not ruling anything out but since I used the same investment with the metal ceramic rings today with no failure in the burnout I am going crazy.

I agree with the different time to set but I try and keep the lab at a very constant temperature from day to day.

 

[dmonwaxa]

John with all due respect, please indicate that its the "burnout" oven you were refering to and it was at the burnout stage.

The way it reads could be the source of confusion, and for me that doesnt take much.

"We had a very frustrating morning in our EMAX department that cost me a bunch of money. We had 5 200 Gram rings fracture on us today. 3 of the 5 failed in the oven and 2 had hairlines that we pressed and they failed.

 

[Al.]

Al I am not ruling anything out but since I used the same investment with the metal ceramic rings today with no failure in the burnout I am going crazy.

I agree with the different time to set but I try and keep the lab at a very constant temperature from day to day.

Its more than just air temp also humidity plays a big roll.

 

[dmonwaxa]

John, the rings that were cast, were they 100g or 200g rings. Al. may have something here and others have alluded to moisture and temp. The 200g rings may simply be retaining more moisture than 100g. This may require you to seperate and dry out a bit longer. With the cold weather outside my investments have been acting up. Just orderd some new stuff tthis morning. If theres any consolation, youre not alone.

 

[JohnWilson]

John with all due respect, please indicate that its the "burnout" oven you were refering to and it was at the burnout stage.

The way it reads could be the source of confusion, and for me that doesn't take much.

"We had a very frustrating morning in our EMAX department that cost me a bunch of money. We had 5 200 Gram rings fracture on us today. 3 of the 5 failed in the oven and 2 had hairlines that we pressed and they failed.

Your right Troy, my mind is fried and my face is red from frustration. I reread my original post and it certainly could be hard to understand.

We have been on the bulk program with Whipmix so the investment comes in big bags not 100 Gram packages like most of you are used to, When we open a bag of powder we pour it into a big sealed container that we put a big desiccate bag in. We attempt to control the humidity by going this extra step. I always felt the single use bags were less sensitive to moisture because of them being sealed till you need to use them.

 

[dmonwaxa]

"A side note ee invested and cast 5 ceramic alloy rings today with no trouble or cracks with the same batch of investment"

John were thes rings handled the same? ie same size rings, same bench set, placed in hot oven/cold oven etc?

 

[TheLabGuy]

I use Formula 1 and have for a couple years now for all of my pressings and never had one crack. However, I am usually doing 100 gram rings most of the time not 200 gram. I will say I do let them set up for a good half hour (especially during the winter months) before I throw them in a heated oven. Maybe Formula 1 isn't stable enough in a large amount (200gm),the expansion forms a crack, like real thick concrete does, just a thought. Is anyone using a 300 gm ring with Formula 1, I'm sure it would be really noticeable if that hypothesis is true?

 

[user name]

Possible wrong liquid, patterns too crowded or close to the ring? Using a different wax/resin for patterns thats expanding before it escapes...rings put in oven w hole up? Pattern material caught fire in the oven and temporarily over heated rings.

???????????????????

 

[JohnWilson]

"A side note ee invested and cast 5 ceramic alloy rings today with no trouble or cracks with the same batch of investment"

John were thes rings handled the same? ie same size rings, same bench set, placed in hot oven/cold oven etc?

The ceramic rings all invested and burned out the same as the pressible rings we did however only cast small rings not the big ones.

We ran the air conditioner yesterday for the first time in a long time "it was actually 86 here in so cal" I wonder if the humidity was changed drastically to have this happen today??? Who knows

If I had not had such great success with this product I would just bail on it.

Rob we have NEVER had a failed 100 gram ring ever with ANY investment I think the bigger the ring the more precise the dry of the ring is a must before its put in a hot oven. Whipmix calls for a 15 min bench set and we use a timer.

Oh well tomorrow is another day lets pray for less stress.

Thanks for your help guys

 

[dmonwaxa]

Humidity!!! As some have stated regarding moisture. The 200g rings are retaining too much moisture prior to burning out, this may lead to steam cracks and tears. I've seen it before where the whole top has blown off because of too much moisture.

 

[user name]

After you pull off the silicone ring, bench set 3 minutes. That will dissipate alot of moisture.